Electrocortical effects of MDMA are potentiated by acoustic stimulation in rats

Abstract

3,4-Methylenedioxymethamphetamine (MDMA; ecstasy) is known for its toxicological, psychopathological and abuse potential. Some environmental conditions, e.g. acoustic stimulation typical of the "rave scene" can influence the toxicity of this drug.
We investigated the effects of low doses of MDMA in vivo using Wistar rats in the absence of acoustic stimulation (white noise; 95 Db) demonstrating that ecstasy is able to induce a significant activation (reduction of Electrocortical total power) of the telencephalic cortex that spontaneously reverts in the absence of sensorial stimuli, whereas it persists for several days if, in addition to MDMA, the animals are exposed to acoustic stimulation.
Our data demonstrate that low doses of MDMA are able to reduce electrocortical total power, and that this effect is potentiated by sensorial stimuli commonly present in certain environments, such as rave parties.

Full text

BioMed Central
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BMC Neuroscience
Open Access
Research article
Electrocortical effects of MDMA are potentiated by acoustic
stimulation in rats
Michelangelo Iannone*
1
, Stefania Bulotta
2
, Donatella Paolino
2
,
Maria Cristina Zito
2
, Santo Gratteri
2
, Francesco S Costanzo
†3
and
Domenicantonio Rotiroti
†1,2
Address:
1
CNR – Institute of Neurological Science, Section of Pharmacology, Catanzaro, 88021, Roccelletta di Borgia, Catanzaro, Italy,
2
Faculty of
Pharmacy, University "Magna Græcia" of Catanzaro, Catanzaro, 88021, Roccelletta di Borgia (CZ) Catanzaro, Italy and
3
Faculty of Medicine and
Surgery, University "Magna Græcia" of Catanzaro, Viale Europa, Località Germaneto, Catanzaro, Italy
Email: Michelangelo Iannone* - m.iannone@isn.cnr.it; Stefania Bulotta - bulotta@unicz.it; Donatella Paolino - dpaolino@unict.it;
Maria Cristina Zito - crizito@libero.it; Santo Gratteri - m.iannone@isn.cnr.it; Francesco S Costanzo - fsc@unicz.it;
Domenicantonio Rotiroti - rotiroti@unicz.it
* Corresponding author †Equal contributors
Abstract
Background: 3,4-Methylenedioxymethamphetamine (MDMA; ecstasy) is known for its
toxicological, psychopathological and abuse potential. Some environmental conditions, e.g. acoustic
stimulation typical of the "rave scene" can influence the toxicity of this drug.
Results: We investigated the effects of low doses of MDMA in vivo using Wistar rats in the
absence of acoustic stimulation (white noise; 95 Db) demonstrating that ecstasy is able to induce a
significant activation (reduction of Electrocortical total power) of the telencephalic cortex that
spontaneously reverts in the absence of sensorial stimuli, whereas it persists for several days if, in
addition to MDMA, the animals are exposed to acoustic stimulation.
Conclusion: Our data demonstrate that low doses of MDMA are able to reduce electrocortical
total power, and that this effect is potentiated by sensorial stimuli commonly present in certain
environments, such as rave parties.
Background
The use of illicit drugs such as 3,4-Methylenedioxymeth-
amphetamine (MDMA; ecstasy) has increased among
young people in Europe and North America [1,2] over the
past years.
Concern has been expressed about the increasing popular-
ity of this stimulant drug and its association with certain
youth subcultures, in particular the dance music scene [3].
The widespread use of ecstasy is due to its ability to pro-
duce feelings of euphoria and energy and a desire to
socialize. In addition to these positive effects, MDMA is
relatively inexpensive to produce and purchase and has
the reputation of being safer than other recreational
drugs.
Yet there is mounting evidence that ecstasy does not
deserve this rosy reputation. In fact, evidence has been
accumulated, both in human and animal studies, that
Published: 16 February 2006
BMC Neuroscience 2006, 7:13 doi:10.1186/1471-2202-7-13
Received: 28 July 2005
Accepted: 16 February 2006
This article is available from: http://www.biomedcentral.com/1471-2202/7/13
© 2006 Iannone et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0
),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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The effects of MDMA and acoustic stimulation on ECoG power spectrumFigure 1
The effects of MDMA and acoustic stimulation on ECoG power spectrum. Effects of MDMA administration in the
presence or absence of sound stimulation on Electrocortical (ECoG) power spectrum power in rats at various times after
administration. (A) short term (180 min) and (B) long term (5 days) evaluation of ECoG power changes.
A
0
10
20
30
40
50
60
70
80
90
100
110
120
30 60 90 180
Time (minutes) from administration
% changes of ECoG spectrum power (
P
V)
saline
saline + sound
MDMA 3 mg/Kg
MDMA 3 mg/Kg + sound
MDMA 6 mg/Kg
MDMA 6 mg/Kg + sound
*p<0,001 vs. saline, saline+sound, MDMA 3 mg/Kg, MDMA 6 mg/Kg
**p<0.001 vs. saline, saline+sound, MDMA 3 mg/Kg
***p<0.001 vs. saline, saline+sound, MDMA 3 mg/Kg, MDMA 3 mg/Kg+sound, MDMA 6mg/Kg
**
*
*
*
*
***
***
***
***
**
**
**
% changes of ECoG spectrum power ( PV)
*
*
*
130
120
110
100
90
80
70
60
50
40
30
20
10
0
B
24 hours 3 days 5 days
Time from administration
*p<0.001vs. Saline, saline+sound, MDMA 3 mg/Kg, MDMA 3 mg/Kg+sound, MDMA 6 mg/Kg

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shows the possible risks engendered by the consumption
of MDMA [4]. In many reviews these risks are extensively
discussed in terms of toxicity, psychopathology and abuse
potential associated with acute and chronic use [5].
It is also clear that some environmental conditions can
influence the toxicity of this drug in humans. For example,
one of the consequences of the use of ecstasy at "raves" is
the increase in body temperature that is due to a direct
action of the drug on the thermoregulatory system, to the
intense muscular activity and to elevated environmental
temperatures. In addition, evidence from research done
with an assortement of animal species from rodents to
non-human primates, has shown that ecstasy is neuro-
toxic [5]. In fact, it has been shown that ecstasy is able to
cause serotonergic [6,7] and dopaminergic [8] neuronal
toxicity in every animal species tested and short-term
changes in the noradrenergic system [5].
It has also been repeatedly demonstrated that electroen-
cephalography may be a cheap and effective tool for
examining neurotoxic effects of MDMA in humans where
ecstasy use is positively correlated with absolute power
changes in some frequency bands [4,9].
One of the questions which need addressing by research is
how other factors typical of the "rave scene", such as sen-
sorial auditory (techno music) stimuli, can affect higher
neural functions and in particular electrocortical activity
[10].
Based on these evidences, we investigated whether sound
stimulation affects electrocorticographic changes of total
spectrum power induced by simultaneous administration
of low doses of MDMA in rats.
Results
Short term evaluation
In the short term evaluation set of experiments, the
administration of saline did not induce any modification
in ECoG total spectrum power values in rats exposed to
acoustic stimulation with respect to non-stimulated ani-
mals (Fig 1A).
The systemic administration of MDMA (3 mg/kg) was not
able to modify ECoG total spectrum power values with
respect to saline treated animals. On the contrary, in
MDMA-treated (3 mg/Kg) animals, acoustic stimulation
induced a significant reduction in ECoG total spectrum
power with respect to saline -sound off (P < 0.001; F =
0.92), saline -sound on (P < 0.001; F = 0.94) and MDMA-
sound off (P < 0.001; F = 1.2) treated animals (Fig. 1A).
MDMA administered at the dose of 6 mg/kg -sound off
induced a marked decrease of ECoG total spectrum power
in comparison to control (saline-treated sound off; P <
0.001; F = 0.89) and MDMA (3 mg/Kg) -sound off (P <
0.001; F = 0.78) group. Sensorial stimulation enhanced
ECoG activation with respect to the control (saline-treated
-sound on; P < 0.001; F = 0.96), MDMA (3 mg/Kg) -sound
off/sound on (P < 0.001; F = 0.95/P < 0.001; F = 0.82) and
MDMA 6 mg/Kg -sound off (P < 0.001; F = 0.97) (Fig. 1A).
In all the experiments the effects of MDMA became evi-
dent within 1–3 min after the treatment.
Long term evaluation
In the long term evaluation set of experiments, animals
treated with saline-sound off did not show any change of
ECoG total spectrum power values with respect to rats
treated with saline-sound on, MDMA 3 mg/Kg -sound off,
6 mg/Kg -sound off and MDMA 3 mg/kg -sound on. These
effects lasted 120–180 min after administration and the
evaluation of ECoG total spectrum power 24 h, 3 and 5
days after treatment, did not evidence any difference with
respect to the control (saline-treated) group (Fig. 1B).
On the contrary, the long term evaluation of ECoG
parameters in animals treated with the higher dose of
MDMA (6 mg/kg) -sound on, evidenced a significant
decrease of total spectrum power values 24 h, 3 and 5 days
after treatment with respect to the control (saline-sound
off; P < 0.001; F = 0.90), saline-sound on (P < 0.001; F =
0.88), MDMA (3 mg/Kg) -sound off (P < 0.001; F = 0.87)/
-sound on (P < 0.001; F = 0.95) and to MDMA (6 mg/Kg)
-sound off (P < 0.001; F = 0.94) treated animals.
Discussion
The most relevant finding in these experiments is that rats
exposed to an acoustic stimulation (95 Db) that per se
does not modify the electrocortical parameters evaluated,
show, after the administration of MDMA, a marked
increase in electrocortical activity with respect to animals
treated with the same dose of drug but in absence of sen-
sorial stimulation.
In particular, the lower dose of MDMA used (3 mg/Kg)
was not able to modify electrocortical parameters consid-
ered only in absence of sound stimulation when, in the
same treatment group, the administration of sound signif-
icantly reduced the ECoG power. In addition, the admin-
istration of a single dose of 6 mg/kg of MDMA, induced
(in the presence of acoustic stimulation), significant stim-
ulation of the electrical activity of the brain cortex lasting
for five days after the administration of the drug.
The mechanisms underlying these differences in the dura-
tion of effects of similar treatments (MDMA 3 or 6 mg/kg
-sound on) remain obscure; however, one might speculate
that the higher (6 mg/kg) dosage of MDMA used in the

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present study might have produced a comparable cross-
sensitisation of the animals to react with higher (and long
lasting) electrocortical activity to acoustic stimuli.
Also the neurochemical basis of the synergism between
noise exposure and MDMA call for more in-depth studies
aimed at disclosing the fine mechanisms underlying this
enhancement. In fact it has been well demonstrated that
exposure to MDMA produces in mice long-lasting EEG
changes and latent brain hyperexcitability, as shown by
persistent changes in baseline and activated EEG, seizure
facilitation and latent metabolic hyperactivity and that
these effects are concomitant with monoamine depletion
within limbic regions and basal ganglia [8], and studies
focused on the basal ganglia circuitry [11], evidentiate
that neurotoxicity affect either serotonin (5-HT) or/and
dopamine (DA) nerve endings.
Indeed, the data available in literature mainly relate to
tests on animals, in which the short- and long-term neu-
rotoxic effects of MDMA are evaluated following adminis-
tration of high doses (ranging from 10 to 20 mg/kg)
which in some studies are repeated for as long as seven
consecutive days [1,5,8,10].
It has been also well demonstrated that acoustic stimula-
tion combined with ecstasy produces a selective enhance-
ment of neurotoxicity (nigrostriatal damage) [8] and
cardiotoxicity [12] in the mouse.
Despite the increasimg number of evidences demonstrat-
ing the synergism between noise and MDMA in inducing
toxical effects, it is very difficult to indicate the mechanism
underliyng these effects. The persistence of the electrocor-
tical effects need in-depht studies aimed at elucidating the
link between serotonergic and acoustic systems and the
biochemical changes induced by MDMA and noise –
treatment.
Our experiments evaluated the effect on animals of low
doses of MDMA associated with sensorial (acoustic stim-
uli) comparable to those occurring in human life within
young people's social gatherings of the "rave" or "techno"
type, whose habitués are known to regularly take this type
of drug, especially during parties chiefly characterised by
strong sensorial stimulations.
Conclusion
Taken together, our data demonstrate that MDMA, even
taken in low doses, is capable of reducing the total power
of the electrocorticographic spectrum, a parameter for the
evaluation of the activation of the telencephalic cortex, in
rats.
In our experimental conditions this activation spontane-
ously reverts in the absence of sensorial stimuli, whereas
it persists for several days if, in addition to MDMA, the
animals are exposed to acoustic stimulation.
We can therefore state that the effects of this drug could be
potentiated by relatively common environmental factors
and stress the potential danger for man of substances that
have been so "popularly" accepted as relatively "safe"
owing to their "short term" effects.
Methods
Adult male Wistar rats weighing 250–280 g (three months
old) were obtained from Charles River (Milan, Italy) and
housed in a temperature (20°C) and humidity (60%)-
controlled colony room. The colony, in pathogen-free
conditions, was maintained in a 12 h light/dark cycle with
light on at 7.00 a.m. with both laboratory food and tap
water available ad libitum.
The experimental protocol and procedures used meet the
guidelines of the Ministry of Health (G.U. n. 40, Feb. 18,
1992) for the use of laboratory animals in Italy.
Rats were anesthetized with chloral-hydrate (400 mg/kg
i.p., Sigma Chemical Co., St. Louis, MO, USA) and placed
in a Kopf stereotaxic apparatus. For each rat, four hand-
made steel epidural electrodes were inserted through a
hole drilled in the skull onto each fronto-parietal cortex 2
mm behind the bregma and ± 2 mm laterally to the mid-
line. In detail, they were produced from a 1.5-mm diame-
ter wire, which was molded and flattened on one side, and
was then bent to 90°. The flattened end of the electrode
possessed a recording surface of 2.25 mm
2
and was placed
right below the skull through a burr hole. The electrodes
were kept in place by dental acrylic cement and jeweler
screws, for chronic EEG recordings (see [11]). The animals
were allowed 1 week to recover before testing.
Before experiments, the animals were placed individually
in a sound-proof Mercury chamber modified to allow
simultaneous ECoG recording (Scalone, Italy) and
allowed 30 min to acclimatize to the new environment.
In awake, freely moving animals, ECoG traces were con-
tinuously recorded for 60 min before and 180 min after
drug injection by connecting the electrodes to an 8 chan-
nel EEG recorder (ERA-9; OTE Biomedica, Florence, Italy).
For long-term evaluation, animals were returned to testing
in the same conditions 24 h, 3 and 5 days after treatment.
Spontaneous and treatment-induced changes in the
domain of the total ECoG spectrum power (0.25–16 Hz)
were monitored continuously for periods of 30 seconds.
Computerized quantitization of changes in ECoG signal
amplitude (µV) was obtained with the aid of a Berg-Fou-

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rier analyser (OTE Biomedica, Florence, Italy). For statisti-
cal purposes, ECoG signal amplitude was expressed as
mean ± s.e. mean percentage changes from control ampli-
tude. The resulting means from control and test experi-
ments were evaluated statistically for differences by prior
two way ANOVA followed by Tukey Test. The parameters
evaluated were: stimulation (sound on vs sound off) and
treatment (saline vs dose of MDMA used). ECoG activity
Electrocorticographic activity changes in dependence of sensorial stimuli in MDMA – treated ratsFigure 2
Electrocorticographic activity changes in dependence of sensorial stimuli in MDMA – treated rats. Sequential
spectral analysis illustrating the effects of (A) MDMA (6 mg/kg; i.p.) and (B) sound (95 dB) + MDMA (6 mg/Kg; i.p.) on electro-
corticographic activity in rats. The ECoG activity, evaluated at various times after treatment shows a marked decrease in total
power after simultaneous administration of sound (A VS B).
A-sound off B-sound on
180
120
90
60
30
0
04 812160481216
= MDMA administration
= Sound on
Time
(
minutes
)
Frequency bands (Hz)

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was monitorized 24 h, 3 and 5 days after by repeating
recording in the same conditions but omitting pharmaco-
logical treatment or acoustic stimulation.
For the sensorial stimulation rats were exposed for all the
duration of the first electrocortical recording (60 min
before and 180 min after administration; in no case ani-
mals were exposed to another session of acoustic stimula-
tion) to continuous white noise produced by two
loudspeakers (set at 95 dB) driven by a white-noise gener-
ator (0–26 kHz), which was installed 30 cm apart from
the cage. The sound level was monitored by a sound level
meter (Quest electronics, 215) and it was uniform
throughout tha cage. The level of loud noise was selected
in order to mimic the same intensity to which humans are
exposed in the discoteques (95 dB is the maximum inten-
sity permitted from the Italian law).
3,4-Methylenedioxymethamphetamine, purchased from
SALARS (Como, Italy), was dissolved in normal saline.
Rats (n = 5 for each group) were randomly assigned to one
of the regimens, each receiving one intraperitoneal injec-
tion of either normal saline (0.5 ml) or MDMA (3 or 6
mg/kg; 0.5 ml) with sound (95 Db) on or off.
Thus, the treatment regimens were as follows: Sound off +
saline; Sound on + saline; Sound off + MDMA; Sound on
+ MDMA. The administration of sound was started 60
min before the injection of saline or MDMA.
Authors' contributions
MI coinceived and coordinated the study and performed
electrocortical analisys. SB, DP and MCZ carried the study
and performed the statistical analysis. SG participated in
design and coordination of the study and helped to draft
the manuscript. FSC and DR supervised the study. All
authors read and approved the final manuscript.
Acknowledgements
Our thanks go to Mr Frustaci S., Mr Macrì A. and Mr Saturnino D. for excel-
lent technical assistance, to Mr Apuzzo D. for administrative assistance and
for english revision of the manuscript to Mrs Lynn Ann Whitted. To mr.
Benito Rocco Scalone (Girifalco, Catanzaro, Italy) go our particular thanks
for the realization of the technical apparatus. This work was economically
supported from the Presidence of Calabria Region, Italy.
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