Preclinical pharmacology of F-98214-TA, a novel potent serotonin and norepinephrine uptake inhibitor with antidepressant and anxiolytic properties.

Abstract

Serotonin (5-HT) and norepinephrine (NE) re-uptake inhibitors (SNRIs) have been proposed to have a higher efficacy and/or faster onset of action than previously available antidepressants.
We examined in biochemical, electrophysiological and behavioural assays the antidepressant properties of (S)-(-)-4-[(3-fluorophenoxy)-phenyl]methyl-piperidine (F-98214-TA), a compound that displays very high affinity for 5-HT and NE transporters.
F-98214-TA potently inhibited the uptake of both 5-HT and NE into rat brain synaptosomes (IC50 = 1.9 and 11.2 nM, respectively) and decreased the electrical activity of dorsal raphe serotonergic neurones (ED50 = 530.3 microg/kg i.v.), an effect completely abolished by the 5-HT(1A) antagonist WAY100,635. In acute behavioural assays in mice, the orally administered compound potentiated the 5-hydroxy-tryptophan (5-HTP)-induced syndrome [minimal effective dose (MED) = 10 mg/kg], antagonized the hypothermia induced by a high dose of apomorphine (ED50 = 2 mg/kg) and reduced the immobility in the tail suspension test (MED = 10 mg/kg). Moreover, it also decreased the immobility in the forced swimming test in mice and rats (30 mg/kg, p.o.). Chronic administration of F-98214-TA (14 days, 30 mg kg(-1) day(-1), p.o.) attenuated the hyperactivity induced by olfactory bulbectomy in rats, confirming its antidepressant-like properties. Interestingly, the same dosage regimen significantly increased the social interaction time in rats, suggesting an additional potential anxiolytic activity. In most assays the compound was more potent than fluoxetine, venlafaxine and desipramine.
F-98214-TA is a novel SNRI that displays greater potency than other reference antidepressants in animal models predictive of antidepressant and anxiolytic activities.

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Psychopharmacology (2005) 182: 400–413
DOI 10.1007/s00213-005-0087-3
ORIGINAL INVESTIGATION
Inés Artaiz.Arturo Zazpe.Ana Innerárity.
ElenadelOlmo.AlvaroDíaz.JoséAngelRuiz-Ortega.
ElenaCastro.RuthPena.LuisLabeaga.Angel Pazos.
Aurelio Orjales
Preclinical pharmacology of F-98214-TA, a novel potent serotonin
and norepinephrine uptake inhibitor with antidepressant
and anxiolytic properties
Received: 14 February 2005 / Accepted: 31 May 2005 / Published online: 21 July 2005
# Springer-Verlag 2005
Abstract Rationale: Serotonin (5-HT) and norepineph-
rine (NE) re-uptake inhibitors (SNRIs) have been proposed
to have a higher efficacy and/or faster onset of action
than previously available antidepressants. Objectives: We
examined in biochemical, electrophysiological and behav-
ioural assays the antidepressant properties of (S)-(−)-4-[(3-
fluorophenoxy)-phenyl]methyl-piperidine (F-98214-TA), a
compound that displays very high affinity for 5-HTand NE
transporters. Results: F-98214-TA potently inhibited the
uptake of both 5-HT and NE into rat brain synaptosomes
(IC50=1.9 and 11.2 nM, respectively) and decreased the
electrical activity of dorsal raphe serotonergic neurones
(ED50=530.3 μg/kg i.v.), an effect completely abolished by
the 5-HT1Aantagonist WAY100,635. In acute behavioural
assays in mice, the orally administered compound poten-
tiated the 5-hydroxy-tryptophan (5-HTP)-induced syndrome
[minimal effective dose (MED)=10 mg/kg], antagonized
the hypothermia induced by a high dose of apomorphine
(ED50=2 mg/kg) and reduced the immobility in the tail sus-
pension test (MED=10 mg/kg). Moreover, it also decreased
the immobility in the forced swimming test in mice and rats
(30 mg/kg, p.o.). Chronic administration of F-98214-TA
(14 days, 30 mg kg−1day−1, p.o.) attenuated the hyperac-
tivity induced by olfactory bulbectomy in rats, confirm-
ing its antidepressant-like properties. Interestingly, the
same dosage regimen significantly increased the social
interaction time in rats, suggesting an additional poten-
tial anxiolytic activity. In most assays the compound was
more potent than fluoxetine, venlafaxine and desipramine.
Conclusions: F-98214-TA is a novel SNRI that displays
greater potency than other reference antidepressants in
animal models predictive of antidepressant and anxiolytic
activities.
Keywords Serotonin.Norepinephrine.Uptake inhibitor.
Antidepressant.Anxiolytic.Animal model
Introduction
Depression is a recurrent and life-threatening mental illness
with a significant incidence in the population, representing
a major social and economic burden (Wong and Licinio
2001). Whereas several classes of antidepressant medica-
tions are currently prescribed to treat depression, serious
drawbacks exist that require improvement such as the
limitations in efficacy, the multiple unwanted side-effects
and the slow onset of the therapeutic response. Therefore,
the development of novel antidepressants with a significant
therapeutic advantage has become a primary objective of
pharmaceutical research (Tran et al. 2003).
Although the monoamine deficiency hypothesis has
proven to be an excessively simplistic model of the com-
plex pathophysiology of depression (Hindmarch 2001), it
has dominated most of the pharmacological approaches to
its management. The original hypothesis proposed that de-
pression is caused by a deficiency of brain monoamines,
particularly serotonin (5-HT) and norepinephrine (NE),
and that antidepressants exerted their effect by increasing
the corticolimbic availability of monoamines. A major in-
A preliminary report of this work was presented at the 30th Annual
Meeting of the Society for Neuroscience, New Orleans, LA, 2000.
I. Artaiz.A. Zazpe.A. Innerárity.E. del Olmo.R. Pena.
L. Labeaga.A. Orjales (*)
Department of Research, FAES FARMA, S. A.,
Máximo Aguirre 14,
Leioa, 48940, Vizcaya, Spain
e-mail: aorjales@faes.es
Tel.: +34-94-4818300
Fax: +34-94-4818309
A. Díaz.J. A. Ruiz-Ortega.E. Castro.R. Pena.A. Pazos
Department of Physiology and Pharmacology,
University of Cantabria,
Avda. de los Castros s/n,
Santander, Cantabria, 39005, Spain
J. A. Ruiz-Ortega
Department of Pharmacology,
University of the Basque Country,
Leioa, 48940, Spain

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consistency in this hypothesis is the temporal discrepancy
between the timing of the primary biochemical effect of
drugs (minutes, hours) and the onset of therapeutic action
(weeks). More recent theories, based on long-term adaptive
changes in the properties of monoaminergic receptors and/
or signal transduction mechanisms, have been suggested to
explain the delayed therapeutic response to antidepressants
(Millan 2004).
Almost all currently marketed antidepressants inhibit
monoamine re-uptake, or the degradative enzyme mono-
amine oxidase, leading to an increase in the availability of
5-HT and/or NE in the synaptic cleft. Tricyclic antidepres-
sants (TCAs) and monoamine oxidase inhibitors (MAOIs)
interact with the serotonergic and noradrenergic systems
but have many adverse effects as a result of direct or
indirect interactions with multiple neurotransmitter recep-
tors. The introduction of more selective agents, particularly
the selective serotonin re-uptake inhibitors (SSRIs), rep-
resented a significant improvement in terms of safety and
tolerability, and antidepressants such as fluoxetine, sertra-
line and paroxetine have become the mainstay drug
treatments for depression in the last 20 years (Kerrigan
1998). Nevertheless, they are not completely devoid of
side-effects such as nausea, sexual dysfunction and sleep
disorders (Goldstein and Goodnick 1998), and they do not
offer advantages over older antidepressants in terms of
efficacy and faster onset of action (Goodnick and Goldstein
1998).
Clinical studies support that a combined 5-HT and NE
enhancement has greater therapeutic efficacy compared
with the enhancement of either neurotransmitter alone.
Thus, the TCA chlorimipramine, which blocks both NE
and 5-HT transporters (SERTs), was shown to have a
slightly greater clinical efficacy than the SSRIs (Anderson
1998). Moreover, the enhanced antidepressant activity of
the combination of SSRIs and NE-selective TCAs ob-
served in previous studies (Weilburg et al. 1989; Nelson
et al. 1991) was confirmed by a recent double blind study
combining fluoxetine and desipramine (Nelson et al. 2004).
Based on this rationale, several compounds that inhibit
selectively the re-uptake of both 5-HTand NE, and without
a significant affinity for neurotransmitter receptors, have
been developed for the treatment of depression. These
compounds are referred to as mixed 5-HT and NE re-
uptake inhibitors (SNRIs), and include venlafaxine, mil-
nacipran and duloxetine. Clinical studies have shown that
SNRIs are effective and well-tolerated antidepressants (for
reviews see Tran et al. 2003; Zajecka and Albano 2004).
Interestingly, meta-analysis of clinical trials suggests that
venlafaxine may have somewhat superior response and
remission rates than TCAs and SSRIs (Thase et al. 2001;
Anderson 2001). In addition, venlafaxine may present ef-
ficacy in major depression resistant to SSRIs (Saiz-Ruiz
et al. 2002) and a rapid onset of clinical effects when used
in high dosages (Montgomery 1995; Entsuah et al. 1998
Burnett and Dinan 1998). There are data suggesting that
milnacipran and duloxetine share with venlafaxine an
efficacy advantage over SSRIs (Clerc 2001; Goldstein et al.
2004), but the evidence in favour of an early onset of
therapeutic response is still awaited.
Although belonging to the same group of antidepres-
sants, SNRIs display some differences in their pharmaco-
logical profile that may be relevant to their individual
clinical activity. In fact, venlafaxine has a substantially
higher affinity for the SERT than for the NE transporter
(NET; Bymaster et al. 2001), which correlates with its
higher serotonergic activity in vivo (Koch et al. 2003). On
the other hand, milnacipran seems to display a limited
serotonergic activity (Bel and Artigas 1999; Koch et al.
2003), whereas the recently launched duloxetine is prob-
ably the most potent and balanced dual transporter inhibitor
(Bymaster et al. 2001). Regarding side-effects, venlafaxine
and duloxetine have been associated with a risk of in-
duction of hypertension (Thase 1998; Zajecka and Albano
2004), and milnacipran has a higher prevalence of head-
ache, dry mouth and dysuria compared with the SSRIs
(Tran et al. 2003).
With all of the above considerations in mind, the de-
velopment of new SNRIs may provide the opportunity to
obtain compounds with a more suitable blockade of the
5-HT and NE re-uptake processes that, in turn, may result
in improved clinical outcomes in depressed patients. As a
result of our research programme, the compound (S)-(−)-4-
[(3-fluorophenoxy)-phenyl]methyl-piperidine (F-98214-TA)
(Fig. 1) was selected from a series of 4-[(aryl)(aryloxy)
methyl]-piperidines based on its high affinity for the 5-HT
and NETs (Orjales et al. 2003). In the present study, bio-
chemical, electrophysiological and behavioural effects of
F-98214-TA are described.
Material and methods
Animals
Unless otherwise specified below, male Wistar rats weigh-
ing 200–275 g (FAES FARMA, S.A., Spain), Swiss CD-1
mice weighing 24–35 g (FAES FARMA) and guinea-pigs
of 300–350 g body weight (Harlan-Interfauna Ibérica,
S.L., Spain) were used. Indicated weights are those upon
commencement of experiments. The animals were housed
in sawdust-lined cages and in temperature- and humidity-
controlled facilities (temperature, 22±1°C; humidity, 65±
15%) and were maintained in a 12-h light/dark cycle (lights
HN
O
F
F-98214-TA
Fig. 1 Chemical structure of
F-98214-TA
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on at 0800 hours). Guinea-pigs (four per cage) were adapt-
ed to laboratory conditions for at least 2 weeks prior to
testing. Rats (six per cage) and mice (ten per cage) were
adapted for at least 5 days before the start of experiments.
Behavioural assays were carried out in temperature- and
humidity-controlled and sound-attenuated rooms. Access
to standard chow and water was unrestricted except in
acute in vivo assays using the oral route of administration.
In these cases the animals were submitted to food re-
striction during 16–18 h before testing to avoid food in-
terference with drug absorption, and water was substituted
by a solution containing 8% sucrose and 0.2% NaCl.
All animal studies were performed in accordance with
the “European Directive for the Protection of Vertebrate
Animals Used for Experimental and Other Scientific
Purposes” (European Union Directive #86/606/EEC) and
the Guide for the Care and Use of Laboratory Animals
published by the National Institutes of Health.
Binding to monoamine transporters
and to neurotransmitter brain receptors
The affinity of F-98214-TA and reference antidepressant
agents for SERTs, NETs and dopamine (DA) transporters
(DAT), and for diverse brain receptors, was evaluated by
using widely described standard procedures summarized in
Table 1. Animals were killed by guillotine decapitation,
and the whole brains were quickly removed. The various
areas were dissected, weighed and immediately frozen at
−70°C until use.
Monoamine uptake assays
Crude synaptosomal preparations
Rats were killed by guillotine decapitation, and their brains
were quickly removed. The frontal cortex and the striatum
were immediately dissected out, weighed and homoge-
nized in 10 vol of ice-cold 0.32 M sucrose solution with
ten passes of a Teflon pestle Potter-S homogenizer (Braun
Biotech International, Melsungen, Germany) set at 800 rpm.
The homogenates were centrifuged at 1,500 g for 10 min at
4°C, and the resulting supernatants were centrifuged at
18,000 g for 10 min at 4°C. The final pellets were sus-
pended in appropriate volumes of the Krebs bicarbonate
physiological solution (pH 7.4) previously bubbled for
10 min with 95% O2 and 5% CO2. To eliminate the
endogenous monoamines, the synaptosomal suspensions
were incubated at 37°C for 10–15 min. The composition of
Krebs bicarbonate medium was 120.8 mM NaCl, 5.9 mM
KCl, 2.2 mM CaCl2, 1.2 mM MgCl2·6H2O, 1.2 mM
NaH2PO4, 15.5 mM NaHCO3and 11.5 mM α-D-glucose.
The synaptosomal preparations were immediately used for
uptake measurements.
Determination of [3H]5-HT, [3H]NE
and [3H]DA uptake
The uptake assay buffer was the Krebs bicarbonate solution
containing 25 mM Hepes, 10 μM pargyline, 10 μM re-
serpine and 0.1% ascorbic acid (pH 7.4). The uptake was
performed in triplicate in a final volume of 0.5 ml. In the
case of [3H]5-HT, synaptosomes from the frontal cortex
were incubated with the drug concentration and 20 nM
[3H]5-HT (PerkinElmer Life Sciences, 27.5 Ci/mmol) for
2 min at 37°C. Non-specific uptake was determined with
10 μM fluoxetine. For determination of [3H]NE uptake,
synaptosomes from the total cortex were incubated with the
drug concentration and 10 nM [3H]NE (Amersham Phar-
macia Biotech, 52 Ci/mmol) for 5 min at 37°C. Non-
specific uptake was determined with 10 μM nisoxetine. In
DA uptake assays, synaptosomes from striatum were in-
cubated with the drug concentration and 3 nM [3H]DA
(PerkinElmer, 31.6 Ci/mmol) for 5 min at 37°C. Non-
specific uptake was determined with 10 μM mazindol.
Table 1 Standard procedures for monoamine transporter and receptor-binding assays
SiteSpecie (tissue)[3H]-Ligand (nM)Non-specific ligand (μM)Reference
SERT
NET
DAT
5-HT1A
5-HT2A
5-HT1B
5-HT3
5-HT4
D1
D2
α1
α2
H1
Mus
Rat (TCx)
Rat (TCx)
Rat (Str)
Rat (TCx)
Rat (PFCx)
Rat (FCx)
Rat (ECx)
Guinea pig (Str)
Rat (Str)
Rat (Str)
Rat (TCx)
Rat (TCx)
Guinea pig (Cb)
Rat (TCx)
Paroxetine (0.2)
Nisoxetine (0.75)
WIN-35428 (0.6)
8-OH-DPAT (0.4)
Ketanserin (0.8)
GR125743 (2)
LY278584 (1.8)
GR113808 (0.15)
SCH23390 (0.4)
Raclopride (1.0)
Prazosin (0.15)
RX821002 (0.75)
Pyrilamine (1.0)
QNB (0.2)
Fluoxetine (10)
Mazindol (10)
Mazindol (10)
5-HT (10)
Methysergide (1)
5-HT (10)
5-HT (10)
5-HT (100)
R(+)SCH23390 (3)
(+)Butaclamol (1)
Phentolamine (10)
Phentolamine (10)
Astemizole (10)
Atropine (10)
Orjales et al. (2003)
Orjales et al. (2003)
Orjales et al. (2003)
Orjales et al. (2003)
Orjales et al. (2003)
Domenech et al. (1997)
Orjales et al. (2000)
Orjales et al. (2000)
Hess et al. (1986)
Orjales et al. (2000)
Oshita et al. (1991)
Erdbrügger et al. (1995)
Benavides et al. (1995)
Watson et al. (1996)
TCx Total cortex, Str striatum, PFCx prefrontal cortex, FCx frontal cortex, ECx entorhinal cortex, Cb cerebellum
402

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Data analysis for binding and uptake studies
At the end of the incubation period, the binding reaction or
uptake process was stopped, and membranes were filtered
through Whatman GF/B filters (Merck 1821.915, Spain)
pre-soaked in the respective binding or uptake buffer con-
taining 0.05–0.1% polyethyleneimine, using a Brandel
M-24R cell harvester (Reactiva, Barcelona, Spain). Filters
were immediately rinsed three times with 4 ml ice-cold
buffer or 154 mM NaCl solution, dried and immersed into
polyethylene scintillation vials containing 5 ml of Ecos-
cint-H scintillation cocktail (Itisa Biomédica S.A., Madrid,
Spain). The filter-retained radioactivity was determined by
scintillation counting. Binding isotherms and data from
uptake studies were analysed by nonlinear regression of
concentration–effect curve (GraphPad Prism, version 2.0;
GraphPad Software Inc., San Diego, CA, USA) to deter-
mine IC50values. For each assayed drug the IC50mean
value was obtained from a minimum of three independent
experiments using 8–14 drug concentrations. For binding
studies, the inhibition constants (Ki) were calculated from
the Cheng–Prusoff equation: Ki=IC50/[(L/KD)+1] (Cheng
and Prusoff 1973), where L is the concentration of radio-
labelled ligand, and KD, its dissociation constant deter-
mined in specific binding experiments.
Electrophysiological studies
Male Wistar rats weighing 240–280 g (Harlan Ibérica), and
allowed to acclimate to the new environment for at least 5
days before the begining of the experiments, were initial-
ly anaesthetized with an intraperitoneal (i.p.) injection of
chloral hydrate (400 mg/kg, 5 ml/kg) and maintained un-
der full general anaesthesia with supplementary intrave-
nous (i.v.) doses. The jugular vein was cannulated for drug
or anaesthesia administration. Rats were mounted in a
stereotaxic frame, and the dura and sagital sinuses were
removed. Single-barrelled glass micropipettes filled with
2 M NaCl containing 2% Pontamine Sky Blue (3–8 MΩ
impedance in vitro) were implanted in the dorsal raphe
nucleus (DRN; ML 0 mm and AP 1 mm to lambda) with
the aid of a microdriver. Serotonergic cell firing in DRN
was measured using standard extracellular recording meth-
ods (Aghajanian 1978). 5-HT neurones, encountered over
5.6 mm DV, were identified according to their electro-
physiological characteristics: a wide-duration action po-
tential (0.8–1.2 ms) and a spontaneous regular pattern
of firing (0.5–2.5 Hz). Signals were amplified and fil-
tered, and the integrated firing rates were computed and
stored in 10-s bins (Spike2, Cambridge Electronic De-
sign, Cambridge, UK). The mean baseline firing rate was
determined for at least 5 min before the administration
of cumulative i.v. doses of fluoxetine, venlafaxine and
F-98214-TA. The effect of each dose was recorded for
2 min, and a test dose of the 5-HT1Aantagonist N-{2-[4-
(2-methoxyphenyl)-1-piperazinyl]ethyl}-N-(2-pyridinyl)
cyclohexanecarboxamide (WAY100,635, 200 μg/kg i.v.)
was given after maximal inhibition of the neuroneal firing
to confirm the pharmacological specificity of the response.
The number of action potentials after drug administration
were quantified (spikes/10 s) and expressed as a percent-
age of the pre-drug baseline value. Only one neurone per
animal was studied. The ED50values were calculated using
the programme GraphPad Prism, version 2.0 (GraphPad
Software).
Behavioural assays
Potentiation of 5-HTP-induced symptoms in mice
The method was based on that described by Buus Lassen
(1978). Mice were orally dosed with the compounds
60 min before administration of 5-HTP (75 mg/kg i.p.).
This dose of 5-HTP by itself causes no clear behavioural
effects, but produces abnormal aimless jerky hypermotility,
head twitches and tremor in mice previously treated with a
compound that increases central 5-HT availability. Once
the 5-HTP was administered, each mouse was immediately
placed singly in a compartment of the Digiscan Activity
System (see Locomotor activity assays in mice and rats
below) and behaviour, measured as stereotypy counts, was
registered from 15 to 45 min after 5-HTP injection.
Apomorphine-induced hypothermia in mice
The procedure was adapted from that described by Fuxe
and Sjöqvist (1972). Animals were orally dosed with the
compounds, and after a period of 20 min, a first rectal
temperature was measured using a digital thermometer
(mod. 0331, Panlab sl, Barcelona, Spain). After 10 min,
apomorphine was injected (16 mg/kg s.c.), and 20 min after
the injection of apomorphine, climbing behaviour was as-
sessed in a wire-mesh cylinder (10 cm diameter, 12 cm
high) according to the following rating scale: 0, all four
paws on the floor; 1, one or two paws on the cylinder; and
2, three or four paws in the cylinder. A second rectal tem-
perature was measured 10 min later. The difference (°C)
between the two temperature values was calculated for
each animal.
Tail suspension test in mice
Male NMRI mice weighing 25–34 g (Charles River, Bar-
celona, Spain) were used. The procedure was adapted from
that described by Steru et al. (1985). In dose-response
assays, 60 min after oral administration of the compounds,
each mouse was suspended by its tail from a hook con-
nected to a force transducer [F 30 type 372, Hugo Sachs
Elektronik (HSE), Germany], which allowed the detection
of all movements of the animal by connecting it to a poly-
graph recorder (WR 3101, HSE). The duration of im-
mobility (s) was recorded over a 6-min testing period. In
time-course assays independent groups of animals were
tested 1, 3, 6, 18 and 24 h after the oral administration of
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compounds (30 mg/kg). The percentage of reduction of the
immobility time was obtained for each treatment group.
Forced swimming test in mice
Male NMRI mice weighing 25–34 g (Charles River) were
used. The procedure was based on that described by Porsolt
et al. (1978a). Sixty minutes after the oral administration of
compounds, mice were individually forced to swim in an
open cylindrical container (diameter 18 cm, height 27 cm),
containing 17 cm of water at 22±1°C. The total duration of
immobility during the last 4 min of a single 6-min test
session was scored. The animal was judged to be immobile
when it ceased struggling or swimming and remained
floating, making only the necessary movements to keep its
head above the water. Data were analysed using the
Kruskal–Wallis test followed by the Mann–Whitney U test.
The percentage of reduction of the immobility time was
obtained for each treatment group.
FST in rats
The test was performed as previously described (Porsolt
et al. 1978b). Rats were individually forced to swim for
15 min in an open cylindrical container (diameter 22 cm,
height 36 cm) containing 22 cm of water at 24±1°C (pretest
session). Animal weights were in the range of 120–150 g
to prevent an animal from touching the bottom of the
container with their tail. Once the pretest session had
finished, rats were removed and allowed to dry for 15 min
in a cage placed 30 cm below an infrared lamp before re-
turning to their home cage. Twenty-four hours later, they
were placed again in the container for 5 min (test session),
and the total duration of immobility was recorded. A rat
was judged to be immobile when it ceased struggling and
remained floating, making only the necessary movements
to keep its head above the water. Drugs were administered
orally three times: 23.5, 5 and 1 h before the test session.
Olfactory bulbectomy in rats
The method was based on that described by Cairncross
et al. (1978). Sprague–Dawley rats (Centre d’Elevage R.
Janvier, France) were anaesthetized with 2,2,2-tribromo-
ethanol (250 mg/kg i.p. 5 ml/kg). A mid-line scalp incision
was made, and bilateral 2-mm diameter burr holes were
drilled through the skull and dura mater, 6 mm anterior to
bregma and 2 mm lateral to the mid-line. The olfactory
bulbs were removed using a water suction pump. The holes
in the skull were packed with homeostatic sponge, and the
incision was closed with wound clips. Sham-operated rats
received burr holes only. The animals were given 14 days
to recover following surgery and were handled daily to
eliminate any aggressiveness that may otherwise arise.
Imipramine(32mg/kg)andF-98214-TA(10and30mg/kg)
were orally administered once daily in the morning (be-
tween 9:00 am and 12:00 nn) from days 14 to 27 post-
surgery. On the morning of day 28 (22–26 h after the last
administration), rats were placed into a highly illuminated
circular arena (90 cm diameter) surrounded by an alumin-
ium wall. The arena floor was divided into 10-cm squares,
and ambulation (number of squares crossed) was measured
for each animal during a 3-min period by an observer blind
to treatments. At the end of the experiments, the rats were
killed, and their brains were inspected. In the case of
damage to the cortex or olfactory bulbs being not com-
pletely removed, animals were excluded from the analysis
of the data.
Social interaction test in rats
The procedure was adapted from that of File et al. (1996).
In acute assays, animals were estabulated four rats per cage
for at least 14 days before the experiment was carried out.
On the testing day, animals received an i.p. injection with
test compounds, and 30 min after, weight-matched pairs
(±10 g) of rats, having received the same treatment and
belonging to different cages, were placed in opposite
corners of a highly illuminated (300 lux) open-topped
arena (62×62×42 cm) for a 7.5-min session. A camera was
mounted about 2 m above the arena, and the camera was
connected to a monitor in an adjacent room. The observer
recorded from the screen the duration of active social
interaction (i.e. the time spent in grooming, following,
sniffing, biting, jumping or crawling over or under the
other animal). If animals remained adjacent to each other
without any movement for longer than 5 s, scoring was
stopped until active social interaction resumed. At the end
of each session, the test arena was carefully cleaned.
In chronic assays, rats (four per cage) were orally adminis-
tered during 14 days with vehicle, imipramine (32 mg/kg),
venlafaxine (30 mg/kg) or F-98214-TA (30 mg/kg). On day
15, 22–24 h after the last administration, each animal was
firstly individually tested during 30 min for locomotor
activity in the Digiscan Activity System (see Locomotor
activity assays in mice and rats below) and was returned to
its home cage. After at least 1 h had passed, pairs of rats,
having received the same treatment, were tested for social
interaction as described for acute experiments.
Locomotor activity assays in mice and rats
The testing apparatus consisted of eight Digiscan activity
monitors connected to two Digiscan analyzers (Omnitech
Electronics Inc., Columbus, OH, USA). Monitors detect
interruptions of 16 photo beams spaced 2.5 cm apart and
2.5 cm above the floor. For spontaneous locomocotor
activity experiments, rats (one animal per activity monitor)
and mice (two animals per activity monitor) were orally
treated with drugs and immediately placed in individual
test chambers. Distance travelled (cm) was recorded during
3 h (three intervals, 60 min each).
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Statistical analysis
Results of the FST and social interaction assays in rats,
5-HTP potentiation and locomotor activity studies were
analysed by one-way analysis of variance (ANOVA)
followed by Dunnett’s test to detect a significant difference
from the control group. A non-parametric test was used
when normality and/or equal variance test failed, that is, in
the tail suspension and forced swimming tests (FSTs) in
mice, as well as in the olfactory bulbectomy model, where
the Kruskal–Wallis test was carried out, followed by the
Mann–Whitney U test, to compare treatment groups from
the vehicle-treated group. In the apomorphine-induced hy-
pothermia assay, the percentage of reduction in the hy-
pothermic effect of apomorphine was calculated for each
treatment group, and ED50values plus 95% confidence
limits (CL) were obtained according to the method of
Litchfield and Wilcoxon (1949). Analyses were conducted
using the SigmaStat programme for IBM computers (2.03,
SPSS Inc., Chicago, IL, USA) with the exception of the
Mann–Whitney U test, which was performed using the
Analyse-it/Excel programme (version 1.67).
Drugs
F-98214-TA and WAY100,635 HCl were internally syn-
thesized, and venlafaxine HCl was extracted from Vandral
75 (A. Toledo). Fluoxetine HCl was obtained from In-
terquímica SA (Barcelona, Spain), and mazindol, nisox-
etine·HCl, 5-hydroxy-DL-tryptophan, apomorphine HCl,
desipramine HCl and imipramine HCl were purchased
from Sigma (Madrid, Spain). For binding assays, drugs
were dissolved in dimethylsulfoxide (10−2M), and dilu-
tions were made in the buffer as appropriate. In electro-
physiological studies fluoxetine and venlafaxine were
dissolved in saline, whereas F-98214-TA was dissolved
in pure ethanol, making dilutions in saline as appropriate
to a final concentration of 5% ethanol. For behavioural
studies drugs were dissolved or suspended in saline with a
drop of Tween 80 and administered in a constant volume
of 10 ml/kg. Doses of F-98214-TA and venlafaxine are
expressed as the bases.
Results
Affinity of F-98214-TA and reference antidepressants
for cerebral rat monoamine transporters
and for neurotransmitter brain receptors
F-98214-TA exhibited a marked affinity for SERT and
NET in the rat cerebral cortex, with a slight preference for
the former (Kiin nM, 2.0±0.4 and 13.5±0.5, respectively).
A similar pattern of dual interaction with SERT and NET
was obtained with venlafaxine. However, its affinities at
these sites were 26- and 50-fold lower, respectively, than
those of F-98214-TA (Table 2). Fluoxetine displayed a pro-
nounced affinity for SERT (Ki=30.9 nM) and a negligible
affinity for NET, whereas desipramine showed an opposite
pattern of preference (Ki=2.7 nM for NET). All com-
pounds, including F-98214-TA, displayed a low affinity for
DAT. The affinity of the compound, as well as that of
fluoxetine and venlafaxine for several brain receptors, in-
cluding monoaminergic, muscarinic and histaminergic re-
ceptors, was negligible (Ki>1,000 nM, Table 2), whereas
desipramine displayed a moderate affinity for α1-adrener-
gic, H1-histamine and muscarinic receptors.
Effect of F-98214-TA as compared to reference
antidepressants on the [3H]monoamine uptake
into rat brain synaptosomes
Consistently with its high affinity for SERT and NET,
F-98214-TA potently inhibited the uptake of both [3H]5-
HT and [3H]NE into rat cerebral synaptosomes (IC50=1.9
±2.4 and 11.2±4.8 nM, respectively, Table 3). Venlafaxine
inhibited also the uptake of both [3H]5-HT and [3H]NE,
although with clearly less potency than F-98214-TA. As
expected, fluoxetine selectively inhibited the synaptosomal
uptake of [3H]5-HT, while desipramine inhibited potently
and selectively the [3H]NE uptake. Unlike reference an-
Table 2 Affinities of F-98214-TA and reference antidepressants for
monoamine transporters and for brain receptors related to monoam-
inergic transmission or to adverse effects
Site F-98214-TA FluoxetineVenlafaxine Desipramine
SERT
NET
DAT
5-HT1A
5−HT1B
5-HT2A
5-HT3
5−HT4
α1
α2
D1
D2
Mus
H1
2.0±0.4
13.5±0.5
680±168
>1,000
>1,000
>1,000
>1,000
>1,000
>1,000
>1,000
>1,000
>1,000
>1,000
>1,000
30.9±7.7
>1,000
>1,000
>1,000
>1,000
>1,000
>1,000
>1,000
>1,000
>1,000
>1,000
>1,000
>1,000
>1,000
52.0±8.5
719±61
>1,000
>1,000
>1,000
>1,000
Nd
>1,000
>1,000
>1,000
Nd
>1,000
>1,000
>1,000
342±120
2.7±0.3
>1,000
>1,000
>1,000
~1,000
>1,000
>1,000
127±9.6
>1,000
>1,000
>1,000
262±13.9
140±8.5
Data are expressed as mean±SEM Ki(nM) of at least three separate
experiments, each performed in triplicate
Nd Not determined
Table 3 Influence of F-98214-TA and reference antidepressants on
[3H]monoamine uptake into rat cerebral synaptosomes
F-98214-TA FluoxetineVenlafaxineDesipramine
[3H]5-HT
[3H]NE
[3H]DA
1.9±2.4
11.2±4.8
86.8±33.2
59.9±14.9
>1,000
>1,000
116.7±19.0
253±61
>1,000
>1,000
19.2±3.6
>1,000
Data are presented as mean±SEM IC50(nM) of at least three
independent experiments, each performed in triplicate
405

Page 7

tidepressants, F-98214-TA displayed a moderate potency
to inhibit the [3H]DA uptake (Ki=86.8 nM).
Effect of F-98214-TA, fluoxetine and venlafaxine on
the electrical activity of serotonergic neurones in DRN
Single-unit recordings showed the ability of F-98214-TA
to dose dependently and completely inhibit the firing rate
of serotonergic neurones localized into the DRN (ED50=
530.3±47.0 μg/kg i.v., Fig. 2). This action was complete-
ly abolished by the selective 5-HT1A antagonist WAY
100,635 (200 μg/kg i.v., data not shown). Fluoxetine and
venlafaxine displayed a similar pattern of inhibition, with
respective ED50values of 787.0±104.2 and 358.7±44.8
μg/kg i.v.
Potentiation of 5-HTP-induced symptoms in mice
F−98214-TA dose-dependently increased the stereotypy
counts induced by 5-HTP in mice with a minimal effective
dose (MED) of 10 mg/kg (Fig. 3 and Table 4). In a similar
way, venlafaxine and (with less efficacy) fluoxetine sig-
nificantly potentiated the syndrome induced by the 5-HT
precursor at the dose of 30 mg/kg. Desipramine did not
show any 5-HTP potentiating effect.
Apomorphine-induced hypothermia in mice
Administration of apomorphine induced a reduction in core
temperature of mice in the order of 4°C, and this effect was
potently antagonized by F-98214-TA in a dose-dependent
manner (ED50=2 mg/kg, Fig. 4 and Table 4). Desipramine
was slighty more potent, and venlafaxine was slightly less
potent than F-98214-TA, whereas fluoxetine modestly
attenuated the apomorphine-induced hypothermia, reach-
ing a percentage of 60 % of antagonism at the dose of
90 mg/kg. None of the compounds affected core temper-
ature alone or climbing behaviour induced by apomorphine
(not shown).
Tail suspension test in mice
In dose–response assays in the tail suspension test, F-98
214-TA induced at the dose of 10 mg/kg (p.o.) a significant
and marked reduction (73%) of mice immobility (Fig. 5a
and Table 4). Venlafaxine and desipramine mimicked these
actions but were less potent, reaching statistical signifi-
cance at the dose of 30 mg/kg. Only high doses of fluox-
etine (90 mg/kg) displayed activity in this model.
In the time-course study (Fig. 5b) the anti-immobility
effect of F-98214-TA (30 mg/kg) was present 18 h after
administration, whereas that of venlafaxine was significant
only 1 h after administration. In an additional experiment,
mice were given vehicle or F-98214-TA (30 mg/kg, p.o.),
and 18 h later, the mice were singly placed in the locomotor
activity apparatus, and the distance travelled was recorded
for a 30-min period (three samples, 10 min each). No ef-
fect of F-98214-TA on motor activity was detected at
any interval (total distance travelled in control animals,
2,368±689 cm; F-98214-TA-treated group, 2,197±131 cm;
n=16).
FST in mice and rats
Oral administration of F-98214-TA significantly reduced
the immobility time in the FST in mice (Fig. 6a and
Table 4). The reduction of the immobility time was about
80% at 30 mg/kg. In a similar way, venlafaxine dose-
dependently reduced the immobility of the animals with a
percentage of reduction of the immobility of 48% at the
same dose. High doses of desipramine (60 mg/kg) and
fluoxetine (90 mg/kg) were required to reach statistical
0
10
20
10100100010000
30
40
50
60
70
80
90
100
110
Dose (µg/kg i.v.)
% Inhibition of Basal Firing Rate
Fluoxetine
F-98214-TA
Venlafaxine
Fig. 2 Dose-dependent effect of cumulative doses of F-98214-TA,
venlafaxine and fluoxetine on the firing of DRN serotonergic
neurones after intravenous (i.v.) injection. Data are expressed as the
percentageofinhibitionofthebasalelectrical activity.Fluoxetine and
F-98214-TA, n=8 rats/group; venlafaxine, n=5 rats/group
**
**
**
**
**
**
**
**
**
**
**
**
0
1000
2000
3000
4000
5000
6000
Vehicle 310 30 60
Dose (mg/kg, p.o.)
Potentiation of 5-HTP-
Stereotypy Counts
F-98214-TA
Fluoxetine
Venlafaxine
Desipramine
Fig. 3 Potentiation of 5-HTP-induced symptoms in mice by
F-98214-TA and reference antidepressants. Drugs were adminis-
tered 60 min before 5-HTP (75 mg/kg i.p.). Stereotypy counts were
measured from 15 to 45 min after injection of 5-HTP. Data represent
mean±SEM (n≥9). **indicates p<0.01 vs vehicle-treated group
(Dunnett’s test following ANOVA)
406

Page 8

significance. In the FST in rats, F-98214-TA significantly
decreased the duration of the immobility when adminis-
tered at 30 mg/kg (Fig. 6b and Table 4). Venlafaxine and
desipramine also reduced immobility time at doses of 60
and 30 mg/kg, respectively, whereas fluoxetine was in-
active even at the dose of 120 mg/kg.
Olfactory bulbectomy in rats
Removal of the olfactory bulbs produced a characteristic
hyperactivity in bulbectomized animals when placed in the
open field as compared to sham-operated animals (Fig. 7).
This hyperactivity was significantly reduced by chronic
treatment with imipramine (32 mg/kg) and F-98214-TA
(30 mg/kg). Both compounds induced significant increases
in ambulation in sham-operated animals.
Social interaction test in rats
Acute injection of imipramine (3 mg/kg), venlafaxine
(10 mg/kg) and F-98214-TA (10 mg/kg) induced a sig-
nificant decrease in the time spent in social interaction by
pairs of unfamiliar rats placed in a novel and highly il-
luminated environment without a concomitant effect in
locomotion (Table 5). Imipramine at the dose of 10 mg/kg
produced a reduction in both social interaction time and
locomotor activity of the animals. Repeated treatment
with F-98214−TA (30 mg/kg p.o.) for 14 days induced a
significant increase in active social interaction among
pairs of rats, whereas imipramine and venlafaxine (32 and
30 mg/kg p.o., respectively) induced a non-significant in-
crease in social interaction time (Table 5). F-98214-TA
Table 4 Summary of actions of F-98214-TA and reference antidepressants in behavioural models of potential antidepressant activity and on
locomotor activity in rodents
Drug 5-HTP
MED
APO
ED50(95% CL)
TSTa
MED
FST micea
MED
FST ratsa
MED
OB
MED
Locomotor activityb
MiceRats
F-98214-TA
Fluoxetine
Venlafaxine
Desipramine
10
30
30
NE
2.0 (1.0–3.9)
60.7 (24.9–148)
3.6 (1.8–7.4)
0.7 (0.3–1.8)
10 (71%)
90 (45%)
30 (71%)
30 (60%)
30 (80%)
90 (37%)
30 (47%)
60 (54%)
30 (67%)
NE (30–120)
60 (54%)
30 (48%)
30
–
>30
–
60↓
NE (30–90)
NE (10–60)
60↓
NE (10–120)
NE (30–60)
60↑
30↓
Doses are expressed in mg/kg p.o.
5-HTP Potentiation of 5-HTP symptoms in mice, APO antagonism of apomorphine-induced hypothermia in mice, TST tail suspension test in
mice, OB olfactory bulbectomy model in rats, NE no effect (in parenthesis, evaluated dose range), ↓ decrease, ↑ increase
aIn parenthesis, percentage of immobility reduction
bdoses inducing significant changes are indicated
3 30
**
**
**
**
**
**
**
**
**
** **
**
****
**
** **
**
****
**
** **
**
0
20
40
60
80
100
120
140
160
106090
Dose (mg/kg, p.o.)
Immobility Time (s)
Immobility Time (s)
F-98214-TA
Venlafaxine
Fluoxetine
Desipramine
Vehicle
a
0
20
40
60
80
100
120
140
160
Vehicle Venlafaxine F-98214-TA
Treatment (p.o.)
1 h3 h6 h 18 h24 h
b
Fig. 5 Effect of F-98214-TA and reference antidepressants upon the
duration of immobility in the tail suspension test in mice. a Dose–
response assays: drugs were administered p.o. 60 min before test
(6 min). Vehicle groups: □indicates F-98214-TA;•, venlafaxine;□,
fluoxetine and desipramine. b Time-course assays: immobility was
evaluated in independent groups 1, 3, 6, 18 and 24 h after the
administration of compounds. Data represent mean±SEM (n≥9). **
indicates p<0.01 vs respective vehicle-treated group (Kruskal–Wallis
followed by Mann–Whitney U test)
0
20
40
60
80
100
120
140
0.1 0.3 13 10 30 90
Dose (mg/kg, p.o.)
% Antagonism
Apomorphine-hypothermia
F-98214-TA
Fluoxetine
Venlafaxine
Desipramine
Fig.4 Antagonismofapomorphine-induced hypothermiainmiceby
F-98214-TA and reference antidepressants. Compounds were
administered p.o. 30 min before apomorphine injection (16 mg/kg
s.c.).Hypothermiawasestimatedbymeasuringtherectaltemperature
10 min before and 30 min after apomorphine treatment. Data are
expressed as the percentage reversal of each treatment group of the
hypothermic effect induced by apomorphine (n=10). The maximal
decrease reached in a vehicle-treated group was 4.8°C, with absolute
core temperatures of 37.1±0.2°C (before apomorphine) and 32.3
±0.2°C (30 min after apomorphine injection)
407

Page 9

and venlafaxine chronically treated animals showed no
changes in the distance travelled, whereas imipramine pro-
duced a significant reduction in this parameter.
Spontaneous locomotor activity in mice and rats
Significant reductions in spontaneous locomotor activity
in mice were observed 1 h after the oral administration of
F-98214-TA, and desipramine at the dose of 60 mg/kg
(Tables 4 and 6). None of the evaluated compounds sig-
nificantly affected locomotor activity in mice 3 h after
drug administration.
In rats neither fluoxetine (30 and 60 mg/kg) nor
F-98214-TA (10–120 mg/kg) induced significant changes
in spontaneous locomotor activity. Desipramine (30 and
60 mg/kg) and venlafaxine (60 mg/kg) induced, respec-
tively, a significant decrease and increase in the distance-
travelled parameter 3 h after their administration (Tables 4
and 6).
Discussion
The results obtained in the present work indicate that
F-98214-TA is a potent SNRI, active in rodent models
predictive of antidepressant and anxiolytic activity, and
displays a higher potency than the reference antidepres-
sants in most of the performed assays.
In vitro binding experiments showed that the affinity of
F-98214-TA for rat-brain SERTis clearly higher than those
of the SSRI fluoxetine, the SNRI venlafaxine and the
tricyclic desipramine. It also possesses a high affinity for
NET, only surpassed by desipramine, whereas its affinity
for DAT is low, reflecting the high degree of selectivity of
F-98214-TA for SERTand NET. The affinity profiles of the
comparative antidepressants for the aminergic transporters
are in line with those previously described (Owens et al.
1997; Muth et al. 1991).
In correlation with its affinities for the transporters,
synaptosomal uptake studies showed that F-98214-TA in-
hibited 5-HT re-uptake site with 30- and 60-fold higher
potencies than fluoxetine and venlafaxine, respectively,
whereas the inhibition potency at the NE re-uptake site
was similar to that of desipramine and 23-fold higher than
that of venlafaxine. Regarding the dopaminergic system, a
poor correlation was found between the (low) affinity of
F-98214-TA for DAT and its moderate potency to block
the re-uptake process. However, such potency resulted to
be 40-fold and eightfold lower than that for inhibiting
5-HT and NE uptake. The relevance of this dopaminergic
component is unclear at present, taking into account that
no elevation in locomotor activity was observed in rats, a
response expected in the case of an increased dopaminer-
gic neurotransmission (Bymaster et al. 2003). Interest-
ingly, F-98214-TA did not reveal any significant affinity
for neurotransmitter receptors involved in the mediation of
cardiovascular, sedative and anticholinergic side-effects
typically associated with TCAs (i.e. adrenergic-α1, hista-
mine-H1 and muscarinic receptors, Owens et al. 1997;
Brunello and Racagni 1998).
The suppression of the firing rate of serotonergic neu-
rones by re-uptake inhibitors could be considered as an
in vivo index of 5-HT re-uptake blocking potency (Béique
0
20
40
60
80
100
120
140
160
180
Vehicle 310306090
Dose (mg/kg, p.o.)
Immobility Time (s)
**
**
**
**
**
F-98214-TA
Venlafaxine
Fluoxetine
Desipramine
a
0
50
100
150
200
250
Vehicle 10 30 60120
Dose (mg/kg, p.o.)
Immobility Time (s)
F-98214-TA
Venlafaxine
Fluoxetine
Desipramine
****
**
b
Fig. 6 Effect of F-98214-TA and reference antidepressants upon the
duration of immobility in the FST in mice (a) and rats (b). a
Compounds were administered, and 60 min later, immobility time
was evaluated during the last 4 min of a 6-min test session. Vehicle-
treated groups: □ indicates F-98214-TA; •, venlafaxine; and □,
fluoxetine and desipramine. b Animals were submitted to a first
swimming session (15 min), and 24 h later, a second test session
(5 min) was carried out. Compounds were administered 23.5, 5 and
1 h before the test session. Vehicle-treated groups: □ indicates
F-98214-TA; and □, venlafaxine, fluoxetine and desipramine. Sta-
tistical analysis was performed using means of Kruskal–Wallis fol-
lowed by a Mann–Whitney U test (a) and ANOVA followed by
Dunnett’s test (b). Data represent mean±SEM (n≥9). ** indicates
p<0.01 vs respective vehicle-treated group
Fig. 7 Effect of 14 days of treatment with F-98214-TA (F) and
imipramine on the olfactory bulbectomy-induced hyperactivity in the
open field. Doses are expressed in mg kg−1day−1(p.o.). Data
represent mean±SEM (n≥8). †† indicates p<0.01 vehicle-treated
olfactory bulbectomized (OB) rats vs. sham-operated controls
(Mann–Whitney U test). * indicates p<0.05 and **, p<0.01 vs.
respective vehicle-treated group (Kruskal–Wallis followed by Mann–
Whitney U test)
408

Page 10

et al. 1999). In our studies, the electrical activity of sero-
tonergic neurones in the DRN was similarly suppressed
by venlafaxine, fluoxetine and F-98214-TA, and this ef-
fect was totally reversed by WAY100,635, indicating
the involvement of 5-HT1Aauto-receptors in this effect
(Bjorvatn et al. 2000). Venlafaxine and fluoxetine data are
in good agreement with those previously reported by others
(Muth et al. 1991; Czachura and Rasmussen 2000). How-
ever,it is noteworthy that venlafaxine, which displayed low
potency in inhibiting the synaptosomal uptake of [3H]5-
HT, showed a relative high potency in suppressing the
firing rate of raphe neurones. This discrepancy between the
in vivo and in vitro activities has been previously described
not only for venlafaxine (Béique et al. 1999) but also for
the compound S33005 (Millan et al. 2001a). In addition
to pharmacokinetic factors, it has been suggested that a
particularly high activity of re-uptake inhibitors in vivo
may reflect the existence of specific cerebral isoforms of
monoamine transporters, for which these agents display
a higher affinity than revealed by in vitro studies (Millan
et al. 2001a). Additional studies are needed to further
clarify this issue.
The serotonergic and noradrenergic properties of F-98
214-TA were confirmed by in vivo studies in mice. The
behavioural tests used in the present study, the potentiation
of 5-HTP-induced behaviour and the antagonism of apo-
morphine-induced hypothermia, have previously been
related to serotonergic and noradrenergic mechanisms,
respectively (Buus Lassen 1978; Stenger et al. 1987;
Redrobe et al. 1998). In agreement with 5-HT uptake data,
F-98214-TA was the most potent in the 5-HTP model
(MED 10 mg/kg), whereas a threefold higher dose of
fluoxetine and venlafaxine was required to significantly
enhance the effect of 5-HTP. Desipramine did not po-
tentiate 5-HTP-induced responses but was the most potent
drug in antagonizing the hypothermic effect induced by
Table 5 Effect of acute and repeated administration of imipramine, venlafaxine and F-98214-TA in the social interaction test and locomotor
activity in rats
Acute (i.p.)
Dose mg/kg
Chronic (p.o.)
Dose mg kg−1day−1
SI time (s)DT (cm)
SI time (s) DT (cm)
Imipramine0
3
133.3±7.6
104.0±8.4*
92.9±5.3**
128.4±7.2
111.4±5.3
97.9±7.9*
108.3±9.7
83.3±8.1
79.5±6.3*
3,364±449
2,673±253
1,474±228*
3,364±449
3,056±436
2,235±308
3,364±449
2,659±324
2,146±287
0125.4±14.0
152.1±8.0
4,118±308
2,468±304**32
10
0
3
10
0
3
10
Venlafaxine0 87.6±6.5
112.6±12.3
2,592±226
3,073±301 30
F-98214-TA0125.4±14.0
164.9±8.1*
4,118±308
3,533±357 30
Data represent mean±SEM. Locomotor activity was evaluated as distance travelled (DT) during 30 min using the Digiscan system. Social
interaction (SI time, s) was evaluated in pairs of rats during 7.5 min under high light/unfamiliar conditions. In acute studies, tests were
performed 30 min after i.p. injection, and independent groups were used for locomotor activity (n=9–10) and social interaction test (n=8–10
pairs of rats). In chronic assays, drugs were given once daily during 14 days, and locomotor activity (n=14–20) and social interaction
time (n=7–10) were evaluated 22–25 h after the last administration
*p<0.05, **p<0.01 vs. vehicle-treated group (Dunnett’s test following ANOVA)
Table 6 Effect of fluoxetine,
desipramine, venlafaxine and
F-98214-TA on spontaneous
locomotor activity in mice
and rats
Results are expressed as mean
±SEM (n≥9) of distance tra-
velled (cm). Animals were
placed in the activity metre
immediately after administration
*p<0.01 vs respective control
group (Dunnett’s test following
ANOVA)
Dose
(mg/kg p.o.)
Locomotor activity, mice
1 h
Locomotor activity, rats
1 h3 h 3 h
Vehicle
Desipramine
–
3,021±154
2,503±343
2,265±255
1,636±341*
2,807±273
2,680±243
2,909±302
2,755±176
2,418±189
2,610±241
2,350±214
2,258±258
2,060±278
1,490±145*
–
5,936±472
3,932±538
4,098±528
4,005±855
5,256±584
4,847±707
5,161±676
5,825±591
5,054±511
5,237±530
5,520±474
5,096±842
5,921±701
6,440±952
–
3,350±508
–
2,215±234
2,127±246
2,518±250
2,380±251
–
3,578±343
–
3,085±333
4,223±503
3,589±675
3,149±361
3,011±326
2,830±291
6,292±780
–
2,978±368*
2,955±375*
3,260±321
4,299±594
–
5,112±497
–
5,458±741
9,210±1394*
4,467±647
4,284±706
4,058±333
3,888±496
10
30
60
30
60
90
–
10
30
60
10
30
60
120
Fluoxetine
Vehicle
Venlafaxine
F-98214-TA
409

Page 11

apomorphine. F-98214-TA also potently blocked the apo-
morphine hypothermic effect, whereas fluoxetine was
nearly inactive. The relative high potency of venlafaxine
in this model contrasted with its preferential interaction
with SERT vs NET in vitro. Similarly, in vivo effects of
venlafaxine on electrical activity of noradrenergic neurones
in the locus coeruleus, as well as on extracellular levels
of NE in the frontal cortex, also reflect a pronounced
influence upon noradrenergic transmission (Millan et al.
2001a). Moreover, electrophysiological data have pre-
viously shown that noradrenergic effects of venlafaxine
are probably not mediated by serotonergic mechanisms
(Béique et al. 1999). As mentioned above, the peculiarly
high in vivo potency of venlafaxine may reflect the in-
teraction with distinct NE re-uptake processes, which can
be distinguished by their different sensitivities to anti-
depressants (Hughes and Stanford 1998).
In spite of differences between laboratories, predictive
assays of antidepressant activity such as the tail suspension
test and the FST in mice are responsive to major classes of
antidepressants, including tricyclics, SSRIs and SNRIs
(Dalvi and Lucki 1999; Redrobe et al. 1998; Millan et al.
2001b). In agreement with previous reports (Steru et al.
1985), the tail suspension test was, in our hands, more
sensitive than the FST to the action of antidepressant drugs.
F-98214-TA induced marked antidepressant-like effects
and was the most potent drug in both behavioural models.
The weak antidepressant effect displayed by fluoxetine in
both tests was not surprising, since similar results, or even
inactivity, have been previously described with this drug
(Sanchez and Meier 1997; Nielsen et al. 2004). In this
regard, the selection of the mouse strain and the mechanism
of action of the drug seem to be crucial factors in the
detection of the antidepressant-like effect in these tests
(David et al. 2003; Ripoll et al. 2003). In accordance with
other authors (Van der Heyden et al. 1987), previous
internal data from our laboratory (not shown) suggested
that the NMRI strain of mice was the most suitable for the
tail suspension test, and the use of the same strain of mice
in the two models was preferred.
An important factor frequently associated with drug
therapy adherence is the frequency of medication doses. In
this regard, it is generally accepted that treatment regimens
that require once-daily dosing may result in better patient’s
compliance than those requiring multiple doses per day.
SSRIs usually need to be taken once a day, whereas the
standard formulations of SNRIs are generally given twice a
day. In this regard, it is noteworthy that the antidepressant-
like activity of F-98214-TA in the mouse tail suspension
test was present 18 h after its acute administration. This
could suggest a better kinetic profile when compared to
venlafaxine which, according to its short half-life (Burnett
and Dinan 1998), was active only 1 h after its acute ad-
ministration. Pharmacokinetic assays are being carried out
to confirm this potential benefit.
In the FST in rats, F-98214-TA and desipramine ex-
hibited a more potent antidepressant-like effect than ven-
lafaxine. Conflicting results were obtained regarding the
effect of SSRIs in this model, since fluoxetine resulted
inactive in the tested dose range (30–120 mg/kg), whereas
sertraline (30 mg/kg, data not shown) induced a marked
antidepressant-like effect. It has been argued that the
efficiency of SSRIs in the rat FST is highly dependent on
the experimental procedure and animal strain (Borsini and
Meli 1988; Rénéric and Lucki 1998). Thus, whereas some
researchers have found a clear anti-immobility effect with
these compounds (Cervo et al. 1991; Overstreet 1993),
others describe only a weak activity, generally at high
doses, or even inactivity (Lucki et al. 1994; Borsini 1995;
Mochizuki et al. 2002). The re-evaluation of SSRIs in a
modified FST that provides separate scores for two active
behaviours (swimming and climbing) resulted in a con-
sistent antidepressant-like effect characterized by a selec-
tive increase of swimming (Detke et al. 1995). The present
data using the traditional version of the model agree with
those of Mochizuki et al. (2002), who reported conflicting
results regarding the effects of SSRIs in the rat FST and
suggested the apparent relevance of the noradrenergic sys-
tem in this test. In this regard, the potency exhibited by
F-98214-TA is remarkable.
The olfactory bulbectomy in rats has been validated as
a model of depression, and has the advantage over most
other current models, in that many of the behavioural
changes induced by olfactory bulbectomy are reversed
by chronic but not acute antidepressant treatment (Kelly
et al. 1997; Cryan et al. 1998). In a similar way to that
observed with other antidepressants, including SNRIs
(McGrath and Norman 1998; Redmond et al. 1999), chron-
ic treatment with F-98214-TA (30 mg kg−1day−1p.o.)
significantly reduced the increased locomotor activity
seen in the control bulbectomized rats. This finding strong-
ly supports the clinical potential of F-98214-TA as an
antidepressant.
An intriguing finding in the olfactory bulbectomy study
was the increase of ambulation in sham-operated animals
after repeated treatment with imipramine and F-98214-TA.
A possible stimulant effect can be ruled out to explain this
action, since neither imipramine nor F-98214-TA enhanced
the spontaneous locomotor activity of rats after repeated
treatment. On the other hand, the exposure of animals to
stressful conditions, by placing them in a highly illu-
minated, open and novel arena, makes the open field a
suitable procedure to measure anxiety-like behaviours.
Therefore, we hypothesized that the observed hyperactive
behaviour in the open field in imipramine- and F-98214-
TA-treated sham-operated animals may be reflecting a
decrease in the stress-induced inhibition of exploratory
behaviour. To test this possibility, the effect of imipramine
and F-98214-TA was evaluated in the social interaction
test, a well-established model of anxiety that mimicks the
aversive conditions of the open field. Since no data are
avaliable concerning the effect of chronic administration of
SNRIs in this model, we also analyzed the effects of
venlafaxine in the social interaction test. As reported for
some SSRIs (Borsini et al. 2002), acute injection of ven-
lafaxine, F-98214-TA and the lowest dose of imipramine
reduced social interaction without any significant alteration
of motor functions, a response which may be interpreted as
410

Page 12

a specific enhancement in anxiety. A possible mechanism
that may account for this effect is the indirect activation of
5-HT2Creceptors, as it has been previously suggested to
explain the acute anxiogenic effect of SSRIs (Dekeyne
et al. 2000). The decrease in social interaction elicited by
the highest dose of imipramine may be reflecting the
sedative properties of this agent. In contrast to the acute
actions, the sedative effect of imipramine after chronic
treatment was accompanied by a marked, but not signif-
icant, increase in the social interaction time. These results
suggest that adaptive changes after prolonged imipramine
treatment may recruit anxiolytic mechanisms that blunt and
override its acute anxiogenic effect and are in line with the
anxiolytic-like activity reported for imipramine by Popik
and Vetulani (1993) under similar conditions. Neverthe-
less, since the apparent anxiolytic effect of imipramine
could be masked by the marked sedative effect, evaluation
of lower doses with less or no effects on spontaneous
locomotor activity may help to demonstrate more clearly
this activity.
In addition to their efficacy in the treatment of depres-
sion, newer antidepressants, particularly SSRIs and ven-
lafaxine, are increasingly used as first-line agents in the
treatment of anxiety disorders (Kent et al. 1998; Rickels
et al. 2000). Interestingly, 14 days of F-98214-TA treat-
ment produced a significant increase in rat social interac-
tion with no concurrent effect on locomotor activity
consistent with anxiolysis. The magnitude of this increase
was similar to that observed in rats treated with chlor-
diazepoxide for 5 days (5 mg kg−1day−1i.p., data not
shown). Although chronic treatment with antidepressants is
rather inactive in this test (Borsini et al. 2002), our results
are in line with the robust anxiolytic-like effect reported
with paroxetine after 3, but not 2, weeks of treatment
(Duxon et al. 2000). If, as it has been argued by these
authors, the social interaction test models the temporal ef-
fects of SSRIs in the clinic, the present data suggest that
F-98214-TA may have a faster onset of anxiolytic-like
action than paroxetine. Nevertheless, it is important to note
that, although similar high light/unfamiliar conditions were
used in both studies, some methodological issues, such as
the time interval between the last dose of the drug and the
test (1 hvs about 24h in our study), can explainthis different
onset of action. Finally, the same dose of venlafaxine
(30 mg/kg) also increased social behaviour in the absence
of motor effects, but this change was not statistically
significant. A higher dose or a longer treatment period may
be required to induce a clear anxiolytic-like effect.
It is noteworthy that active doses of F-98214-TA in
behavioural tests (10 and 30 mg/kg) had no effect on
spontaneous locomotor activity in rodents. Moreover, the
transient sedation observed in mice at the dose of 60 mg/kg
and the lack of any significant effect of the compound on
spontaneous locomotor activity in rats in the whole dose
range examined (10–120 mg/kg) may be reflecting a
substantial therapeutic window to a generalized disruption
of behaviour. Venlafaxine was devoid of any effect on
spontaneous locomotor activity in mice but induced a
locomotor stimulant effect in rats at the dose of 60 mg/kg.
These findings are consistent with other works showing
species differences in the effects of venlafaxine on loco-
motor activity (Rogóz et al. 1998; Brocco et al. 2002). In
mice, previous data have reported no changes (Rogóz et al.
1998) or increases in locomotor activity (Redrobe et al.
1998; Brocco et al. 2002), although this latter effect has
been suggested to reflect not an effect upon motor function
but upon arousal (Brocco et al. 2002). On the other hand,
our data reveal an acute stimulant action of venlafaxine
in the rat, which contrast with the sedative properties
described by other authors in this specie (Rogóz et al. 1998;
Rénéric and Lucki 1998; Brocco et al. 2002; Millan et al.
2001b). However, it is important to note that such effect
was observed only during the 3-h testing period, a rather
long period not examined in the abovecited studies, and
which could account for the discrepant results. The current
results are in line with recent observations reporting in-
creases in both locomotor activity and striatal DA levels
after chronic treatment with venlafaxine in female rats (de
Oliveira et al. 2004). In addition, as the stimulant effect of
venlafaxine may have contributed to its antidepressant-like
effect in the rat FST, additional spontaneous locomotor
activity studies would be helpful to rule out this possibility.
Finally, fluoxetine did not produce any significant influ-
ence on spontaneous locomotor activity in mice and rats,
whereas desipramine, as expected from its antihistaminer-
gic properties, induced a significant reduction in locomotor
activity in both species.
In conclusion, F-98214-TA is a potent SNRI with an-
tidepressant-like activity, following acute and repeated ad-
ministration in rodents and without significant affinity for
receptors that could mediate adverse effects. Interestingly,
the compound is more potent than desipramine, fluoxetine
and venlafaxine in the majority of the experimental tests
performed in this study. Our data also suggest that this drug
could induce a prolonged therapeutic effect. The potential
anxiolytic activity of F-98214-TA after chronic adminis-
tration represents an added benefit, having in mind the
overlap between anxiety and depression disorders. Upcom-
ing clinical studies will soon indicate how the preclinical
antidepressant-like efficacy translates into antidepressant
activity in humans.
Acknowledgements
istry of Science and Technology of Spain (PROFIT 2000–2003, BFI
01/0592 and 1FD 97/1597) and the Department of Industry, Com-
merce and Tourism of the Basque Country Government (INTEK
2000–2003). R. Pena was granted by the Ministry of Science and
Technology of Spain (MIT fellowship). We thank Begoña González,
Gaizka Akarregi, Iñaki Marcos, Lourdes Lanza and Ma. Josefa
Castillo for technical assistance.
This study was in part supported by the Min-
References
Aghajanian GK (1978) Feedback regulation of central monoamin-
ergic neurons: evidence from single cell recording studies. In:
Youdin MBH, Lovenberg W, Sharman DF, Lagnado JR (eds)
Essays in neurochemistry and neuropharmacology. Wiley, New
York, pp 1–32
411

Page 13

Anderson IM (1998) SSRIs versus tricyclic antidepressants in de-
pressed impatients: a meta-analysis of efficacy and tolerability.
Depress Anxiety 7:11–17
Anderson IM (2001) Meta-analytical studies on new antidepressants.
Br Med Bull 57:161–178
Béique JC, De Montigny C, Blier P, Debonnel G (1999) Venlafaxine:
discrepancy between in vivo 5-HT and NE reuptake blockade
and affinity for reuptake sites. Synapse 32:198–211
Bel N, Artigas F (1999) Modulation of the extracellular 5−hy-
droxytryptamine brain concentrations by the serotonin and
noradrenaline reuptake inhibitor, milnacipran. Neuropsycho-
pharmacology 21:745–754
Benavides J, Schoemaker C, Dana Y, Claustre M, Delahaye M,
Prouteau P, Manoury P, Allen J, Scatton B, Langer SZ, Arbilla S
(1995) In vivo and in vitro interaction of the novel selective
histamine H1receptor antagonist Mizolastine with H1receptors
in the rodent. Arzneim Forsch 45:551–558
Bjorvatn B, Fornal CA, Martín FJ, Metzler CW, Jacobs BL (2000)
Venlafaxine and its interaction with WAY100,635: effects on
serotonergic unit activity and behaviour in cats. Eur J Pharmacol
404:121–132
Borsini F (1995) Role of the serotonergic system in the forced
swimming test. Neurosci Biobehav Rev 19:377–395
BorsiniF,MeliA(1988)Istheforced swimmingtestasuitable model
for revealing antidepressant activity? Psychopharmacology
94:147–160
Borsini F, Podhorna J, Marazziti D (2002) Do animal models of
anxiety predict anxiolytic-like effects of antidepressants? Psy-
chopharmacology 163:121–141
Brocco M, Dekeyne A, Veiga S, Girardon S, Millan MJ (2002)
Induction of hyperlocomotion in mice exposed to a novel en-
vironment by inhibition of serotonin reuptake. A pharmacolo-
gical characterization of diverse classes of antidepressant agents.
Pharmacol Biochem Behav 71:667–680
Brunello N, Racagni G (1998) Rationale for the development of
noradrenaline reuptake inhibitors. Hum Psychopharmacol 13:
S13–S19
Burnett FE, Dinan TG (1998) Venlafaxine. Pharmacology and ther-
apeutic potential in the treatment of depression. Hum Psycho-
pharmacol 13:153–162
Buus Lassen J (1978) Potent and long-lasting potentiation of two 5-
hydroxytryptophan-induced effects in mice by three selective 5-
HT uptake inhibitors. Eur J Pharmacol 47:351–358
Bymaster FP, Dreshfield-Ahmad LJ, Threlkeld PG, Shaw JL,
Thompson L, Nelson DL, Hemrick-Luecke SK, Wong DT
(2001) Comparative affinity of duloxetine and venlafaxine for
serotonin and norepinephrine transporters in vitro and in vivo,
human serotonin receptor subtypes, and other neuronal recep-
tors. Neuropsychopharmacology 25:871–880
Bymaster FP, McNamara RK, Tran PV (2003) New approaches to
developing antidepressants by enhancing monoaminergic neu-
rotransmission. Expert Opin Investig Drugs 12:531–543
Cairncross KD, Cox B, Forster C, Wren AF (1978) A new model for
the detection of antidepressant drugs: olfactory bulbectomy in
the rat compared with existing models. J Pharmacol Methods
1:131–143
Cervo L, Grignaschi G, Rossi C, Samanin R (1991) Role of sero-
tonergic neurons in the effect of sertraline in rats in the forced
swimming test. Eur J Pharmacol 196:217–222
Cheng YC, Prusoff WH (1973) Relationship between inhibition
constant (K1) and the concentration of inhibitor which causes
50 per cent inhibition (I50) of an enzymatic reaction. Biochem
Pharmacol 22:3099–3108
Clerc G, Milnacipran/Fluvoxamine Study Group (2001) Antidepres-
santefficacyandtolerabilityofmilnacipran,adualserotoninand
noradrenaline reuptake inhibitor: a comparison with fluvox-
amine. Int Clin Psychopharmacol 16:145–151
Cryan JF, Mc Grath C, Leonard BE, Norman TR (1998) Combining
pindolol and paroxetine in an animal model of chronic anti-
depressant action. Can early onset of action be detected? Eur J
Pharmacol 352:23–28
Czachura JF, Rasmussen K (2000) Effects of acute and chronic
administration of fluoxetine on the activity of serotonergic
neurons in the dorsal rapphe nucleus of the rat. Naunyn-
Schmiedeberg’s Arch Pharmacol 362:266–275
Dalvi A, Lucki I (1999) Murine models of depression. Psychophar-
macology 147:14–16
David DJP, Renard CE, Jolliet P, Hascoët M, Bourin M (2003)
Antidepressant-like effects in various mice strains in the forced
swimming test. Psychopharmacology 166:373–382
de Oliveira RA, Cunha GM, Borges KD, de Bruin GS, dos Santos-
Filho EA, Viana GS, de Bruin VM (2004) The effect of ven-
lafaxine on behaviour, body weight and striatal monoamine
levels on sleep-deprived female rats. Pharmacol Biochem Behav
79:499–506
DekeyneA,DenormeB,MonneyronS,MillanMJ(2000)Citalopram
reduces social interaction in rats by activation of serotonin (5-
HT) (2C) receptors. Neuropharmacology 39:1114–1117
Detke MJ, Rickels M, Lucki I (1995) Active behaviours in the rat
forced swimming test differentially produced by serotonergic
and noradrenergic antidepressants. Psychopharmacology 121:
66–72
DomenechT,BeletaJ,PalaciosJM(1997)Characterizationofhuman
serotonin 1D and 1B receptors using [3H]-GR-125743, a novel
radiolabelled serotonin 5-HT1D/1Breceptor antagonist. Naunyn-
Schmiedeberg’s Arch Pharmacol 356:328–334
DuxonMS, StarrKR,UptonN(2000) Latency toparoxetine-induced
anxiolysis in the rat is reduced by co-administration of the
5-HT1Areceptor antagonist WAY100635. Brit J Pharmacol 130:
1713–1719
Entsuah R, Derivan A, Kikta D (1998) Early onset of antidepressant
action of venlafaxine: pattern analysis in intent-to-treat patients.
Clin Ther 20:517–526
Erdbrügger W, Raulf M, Otto T, Michel MC (1995) Does [3H]-2-
methoxy-Idazoxan (RX821002) detect more alpha2-adreno-
ceptor agonist high affinity sites than [3H]-Rauwolscine? A
comparison of nine tissues and cell lines. J Pharmacol Exp Ther
273:1287–1294
File SE, Gonzalez LE, Andrews N (1996) Comparative study of pre-
and postsynaptic 5-HT1Areceptor modulation of anxiety in two
ethological animal tests. J Neurosci 16:4810–4815
Fuxe K, Sjöqvist F (1972) Hypothermic effect of apomorphine in the
mouse. J Pharm Pharmacol 24:702–705
Goldstein BJ, Goodnick PJ (1998) Selective serotonin reuptake
inhibitors in the treatment of affective disorders-III. Tolerability,
safety and pharmacoeconomics. J Psychopharmacol 12:S55–
S87
Goldstein DJ, Lu Y, Detke MJ, Wiltse C, Mallinckrodt C, Demitrack
MA (2004) Duloxetine in the treatment of depression: a double-
blind placebo-controlled comparison with paroxetine. J Clin
Psychopharmacol 24:389–399
Goodnick PJ, Goldstein BJ (1998) Selective serotonin reuptake in-
hibitors in the treatment of affective disorders-II. Efficacy and
quality of life. J Psychopharmacol 12:S21–S54
HessEJ,BattagliaG,NormanAB,IorioLC,CreeseI(1986)Guanine
nucleotideregulationofagonistinteractions at[3H]-SCH23390-
labeled D1dopamine receptors in rat striatum. Eur J Pharmacol
121:31–38
Hindmarch I (2001) Expanding the horizons of depression: beyond
the monoamine hypothesis. Hum Psychopharmacol Clin Exp
16:203–218
Hughes ZA, Stanford SC (1998) Evidence from microdialysis and
synaptosomal studies of rat cortex for noradrenaline uptake sites
with different sensitivities to SSRIs. Br J Pharmacol 124:1141–
1148
Kelly JP, Wrynn AS, Leonard BE (1997) The olfactory bulbecto-
mized rat as a model of depression: an update. Pharmacol Ther
74:299–316
Kent JM, Coplan JD, Gorman JM (1998) Clinical utility of the
selective reuptake inhibitors in the spectrum of anxiety. Biol
Psychiatry 44:812–824
412

Page 14

Kerrigan F (1998) Antidepressant patents: 1995–1997. Expert Opin
Ther Pat 8:439–460
Koch S, Hemrick-Luecke SK, Thompson LK, Evans DC, Threlkeld
PG, Nelson DL, Perry KW, Bymaster FP (2003) Comparison of
effects of dual transporter inhibitors on monoamine transporters
and extracellular levels in rats. Neuropharmacology 45:935–944
Litchfield JT, Wilcoxon F (1949) A simplified method of evaluating
dose-effect experiments. J Pharmacol Exp Ther 96:99–113
Lucki I, Singh A, Kreiss DS (1994) Antidepressant-like behavioural
effects of serotonin receptor agonists. Neurosci Biobehav Rev
18:85–95
McGrath C, Norman TR (1998) The effect of venlafaxine treatment
ontheneurochemicalchangesintheolfactorybulbectomisedrat.
Psychopharmacology 136:394–401
Millan MJ (2004) The role of monoamines in the actions of
established and “novel” antidepressant agents: a critical review.
Eur J Pharmacol 500:371–384
Millan MJ, Gobert A, Lejeune F, Newman-Tancredi A, Rivet JM,
Auclair A, Peglion JL (2001a) S33005, a novel ligand at both
serotonin and norepinephrine transporters: I. Receptor binding,
electrophysiological, and neurochemical profile in comparison
with venlafaxine, reboxetine, citalopram, and clomipramine. J
Pharmacol Exp Ther 298:565–580
Millan MJ, Dekeyne A, Papp M, La Rochelle CD, MacSweeny C,
Peglion JL, Brocco M (2001b) S33005, a novel ligand at both
serotonin and norepinephrine transporters: II. behavioural
profile in comparison with venlafaxine, reboxetine, citalopram,
and clomipramine. J Pharmacol Exp Ther 298:581–591
Mochizuki D, Tsujita R, Yamada S, Kawasaki K, Otsuka Y,
Hashimoto S, Hattori T, Kitamura Y, Miki N (2002) Neuro-
chemical and behavioural characterization of milnacipran, a
serotonin and noradrenaline reuptake inhibitor in rats. Psycho-
pharmacology 162:323–332
MontgomerySA(1995)Rapidonsetofactionofvenlafaxine.IntClin
Psychopharmacol 10:21–27
MuthEA,MoyerJA,HaskinsJT,AndreeTH,HusbandsGEM(1991)
Biochemical, neurophysiological, and behavioural effects of
Wy-45,233andotheridentifiedmetabolitesoftheantidepressant
venlafaxine. Drug Dev Res 23:191–199
NelsonJC,MazureCM,BowersMB,JatlowPI(1991)Apreliminary,
open study of the combination of fluoxetine and desipramine for
rapid treatment of depression. Arch Gen Psychiatry 48:303–307
Nelson JC, Mazure CM, Jatlow PI, Bowers MB, Price LH (2004)
Combining norepinephrine and serotonin reuptake inhibition
mechanism for treatment of depression: a double-blind, ran-
domized study. Biol Psychiatry 55:296–300
Nielsen DM, Carey GL, Gold LH (2004) Antidepressant-like activity
of corticotropin-releasing factor type-1 receptor antagonists in
mice. Eur J Pharmacol 499:135–146
Orjales A, Alonso-Cires L, López-Tudanca PL, Tapia I, Labeaga L,
Mosquera R (2000) Sintesis and 5-HT3receptor affinity of new
quinolinecarboxylic acid derivatives. Drug Des Discov 16:271–
279
Orjales A, Mosquera R, Toledo A, Pumar MC, García N, Cortizo L,
Labeaga L, Innerarity A(2003) Syntheses and binding studies of
new [(aryl)(aryloxy)methyl] piperidine derivatives and related
compounds as potential antidepressant drugs with high affinity
for serotonin (5-HT) and norepinephrine (NE) transporters. J
Med Chem 46:5512–5532
Oshita M, Kigoshi S, Muramatsu I (1991) Three distinct binding sites
for [3H]-prazosin in the rat cerebral cortex. Br J Pharmacol
104:961–965
Overstreet DH (1993) The Flinders sensitive line rats: a genetic
animal model of depression. Neurosci Biobehav Rev 17:51–68
Owens MJ, Morga WN, Plott SJ, Nemeroff CB (1997) Neurotrans-
mitter receptor and transporter binding profile of antidepressants
and their metabolites. J Pharmacol Exp Ther 283:1305–1322
Popik P, Vetulani J (1993) Similar action of imipramine and arginine-
vasopressin in the social interaction test. Pol J Pharmacol 45:
323–325
Porsolt R, Bertin A, Jalfre M (1978a) Behavioural despair in rats and
mice: strain differences and the effects of imipramine. Eur J
Pharmacol 51:291–294
Porsolt R, Anton G, Blavet N, Jalfre M (1978b) Behavioural despair
in rats: a new model sensitive to antidepressant treatments. Eur J
Pharmacol 47:379–391
RedmondAM,KellyJP,LeonardBE(1999)Thedeterminationofthe
optimal dose of milnacipran in the olfactory bulbectomized rat
model of depression. Pharmacol Biochem Behav 62:619–623
Redrobe JP, Bourin M, Colombel MC, Baker GB (1998) Dose-
dependent noradrenergic and serotonergic properties of venla-
faxine in animal models indicative of antidepressant activity.
Psychopharmacology 138:1–8
Rénéric JP,Lucki I (1998) Antidepressant behavioural effects by dual
inhibition of monoamine reuptake in the rat forced swimming
test. Psychopharmacology 136:190–197
Rickels K, Pollack MH, Sheehan DV, Haskins JT (2000) Efficacy of
extended-release venlafaxine in non-depressed outpatients with
generalized anxiety disorder. Am J Psychiatry 157:968–974
Ripoll N, David DJP, Dailly E, Hascoët M, Bourin M (2003)
Antidepressant-like effects in various mice strains in the tail
suspension test. Behav Brain Res 143:193–200
Rogóz Z, Dziedzicka-Wasylewska M, Maj J (1998) The pharmaco-
logical profile of venlafaxine, a new antidepressant, given
acutely. Pol J Pharmacol 50:107–115
Saiz−Ruiz J, Ibanez A, Díaz-Marsa M, Arias F, Padin J, Martin-
Carrasco M, Montes JM, Ferrando L, Carrasco JL, Martin-
Ballesteros E, Jorda L, Chamorro L (2002) Efficacy of
venlafaxine in major depresion resistant to selective serotonin
reuptake inhibitors. Prog Neuropsychopharmacol Biol Psychi-
atry 26:1129–1134
Sanchez C, Meier E (1997) Behavioural profiles of SSRIs in animal
modelsofdepression,anxietyandaggression.Aretheyallalike?
Psychopharmacology 129:197–205
Stenger A, Couzinier J-P, Briley M (1987) Psychopharmacology
of midalcipran, 1-phenyl-1-diethyl-amino-carbonyl-2-aminometh-
ylcyclopropane hydrochloride (F 2207), a new potential antide-
pressant. Psychopharmacology 91:147–153
Steru L, Chermat R, Thierry B, Simon P (1985) The tail suspen-
sion test: a new method for screening antidepressants in mice.
Psychopharmacology 85:367–370
Thase ME (1998) Effects of venlafaxine on blood pressure: a meta-
analysis of original data from 3744 depressed patients. J Clin
Psychiatry 59:502–508
Thase ME, Entsuah AR, Rudolph RL (2001) Remission rates during
treatment with venlafaxine or selective serotonin reuptake
inhibitors. Br J Psychiatry 178:234–241
Tran PV, Bymaster FP, McNamara RK, Potter WZ (2003) Dual
monoamine modulation for improved treatment of major de-
pressive disorder. J Clin Psychopharmacol 23:78–86
Van Der Heyden JAM, Molewijk E, Olivier B (1987) Strain dif-
ferences in response to drugs in the tail suspension test for
antidepressant activity. Psychopharmacology 92:127–130
Watson M, Roeske WR, Yamamura HI (1996) [3H]-Pirenzepine and
[3H]-Quinuclidinyl benzilate binding to rat cerebral cortical and
cardiac muscarinic cholinergic sites: characterization and regu-
lation of antagonist binding to putative muscarinic subtypes.
J Pharmacol Exp Ther 237:419–427
Weilburg JB, Rosenbaum JF, Biederman J, Sachs GS, Pollack MH,
Kelly K (1989) Fluoxetine added to non-MAOI antidepressants
converts nonresponders to responders: a preliminary report.
J Clin Psychiatry 50:447–449
Wong ML, Licinio J (2001) Research and treatment approaches to
depression. Nat Rev Neurosci 2:343–351
Zajecka JM, Albano D (2004) SNRIs in the management of acute
major depressive disorder. J Clin Psychiatry 65:11–18
413