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ABSTRACT: The problem of drug-resistant depression indicates a strong need for alternative antidepressant therapies. In our earlier papers we described synergistic, antidepressant-like effects of a combination of imipramine (IMI) and amantadine (AMA) in the forced swimming test in rats, an animal model of depression. Moreover, preliminary clinical data showed that the above-mentioned combination had beneficial effects in treatment-resistant patients. In addition, a number of studies predicted a role of the brain-derived neurotrophic factor (BDNF) in the mechanism of action of antidepressant drugs (ADs). Since the most potent effect of ADs on BDNF gene expression was found after prolonged treatment, in the present study we investigated the influence of repeated treatment with IMI (5 or 10 mg/kg) and AMA (10 mg/kg), given separately or jointly (twice daily for 14 day), on mRNA level (the Northern blot) in the hippocampus and cerebral cortex. The experiment was carried out on male Wistar rats. The tissue for biochemical assays was dissected 24 h after the last dose of IMI and AMA. We also studied the effect of repeated treatment with IMI and AMA on the action of 5-HT(1A)- and 5-HT(2A) receptor agonists (8-OH-DPAT and (+/-)DOI, respectively) in behavioral tests. The obtained results showed that in the hippocampus IMI (10 mg/kg), and in the cerebral cortex IMI (5 and 10 mg/kg) and AMA (10 mg/kg) significantly elevated BDNF mRNA level. Joint administration of IMI (5 or 10 mg/kg) and AMA (10 mg/kg) induced a more potent increase BDNF gene expression in the hippocampus (but not in cerebral cortex) and either inhibited the behavioral syndrome induced by (+/-)DOI or did not change the action of 8-OH-DPAT (compared to treatment with either drug alone). The obtained results suggest that the enhancement of BDNF gene expression may be essential for the therapeutic effect of co-administration of IMI and AMA to drug-resistant depressed patients, and that among other mechanisms, 5-HT(2A) receptors possibly play some role in this effect.
Journal of physiology and pharmacology: an official journal of the Polish Physiological Society 07/2007; 58(2):219-34. · 2.27 Impact Factor
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ABSTRACT: Data acquired to date show that some sigma receptor ligands reveal "antidepressant-like" activity in the forced swim test in mice and rats. Moreover, our preliminary results suggested that joint administration of sigma receptor ligands and amantadine (AMA, a glutamatergic/NMDA receptor antagonist) caused a positive interaction in the Porsolt test in rats, as had already been observed in the case of co-treatment with clinically active antidepressants and AMA. The aim of the present study was to examine the effect of combined administration of sigma1 or sigma2 receptor agonists, SA4503 or siramesine, respectively, and AMA or memantine (MEM) (uncompetitive NMDA receptor antagonist). SA4503 or siramesine given jointly with MEM (as well as with AMA) decreased the immobility time in rats. The effect of SA4503 and AMA co-administration was antagonized by progesterone, a sigma1 receptor antagonistic neurosteroid. Combined treatment with siramesine and AMA was modified by neither progesterone nor BD1047 (a novel sigma antagonist with preferential affinity for sigma1 sites); but it was counteracted by sulpiride and prazosin (a dopamine D2- and an alpha1-adrenergic receptor antagonist, respectively). The "antidepressant-like" effect induced by siramesine and MEM was not antagonized by progesterone, but was attenuated by BD1047, sulpiride and prazosin. The obtained results give support to the hypothesis that sigma (particularly sigma1) receptors may be one of the possible mechanisms by which drugs induce antidepressant-like activity in the forced swim test, and that this effect may be enhanced by NMDA receptor antagonists. Combined treatment with sigma ligands and AMA or MEM (applied in the clinic) may be an alternative to the treatment of antidepressant-resistant depressive patients in the future.
Journal of physiology and pharmacology: an official journal of the Polish Physiological Society 07/2006; 57(2):217-29. · 2.27 Impact Factor
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ABSTRACT: Recent studies indicate a role of the brain-derived neurotrophic factor (BDNF) in the pathophysiology of depression, as well as in the mechanism of action of antidepressant drugs (ADs). It has been shown that serum BDNF levels are decreased in depressed patients. Moreover, antidepressant treatment increases serum BDNF levels and it is positively correlated with medication response. In addition, repeated administration of ADs induces an increase in rat hippocampal or cortical BDNF gene expression. Since the most potent effect of ADs on BDNF gene expression was found after prolonged treatment, in the present study we investigated the influence of repeated treatment (twice daily for 14 days) of the new AD mirtazapine (5 or 10 mg/kg) on BDNF mRNA level (the Northern blot) in rat hippocampus and cerebral cortex. Imipramine was used as a reference compound. The experiment was carried out on male Wistar rats. The tissue for biochemical assays was collected 24 h after the last doses of mirtazapine and imipramine. We also studied the effect of repeated mirtazapine on the action of the 5-HT2A receptor agonist (+/-)DOI in the behavioral test (head twitches induced by (+/-)DOI) in rats. The obtained results showed that, like imipramine (10 mg/kg), mirtazapine (10 mg/kg) increased BDNF gene expression in both the examined brain regions: in the hippocampus by 24.0 and 26.5%, in the cerebral cortex by 29.9 and 41.5%, respectively, compared with the vehicle-treated control. Neither mirtazapine nor imipramine administered repeatedly at a lower dose (5 mg/kg) significantly changed BDNF mRNA levels in the hippocampus and cerebral cortex. Repeated treatment with mirtazapine (10, but not 5 mg/kg) inhibited the behavioral syndrome induced by (+/-)DOI. This study provides first conclusive evidence that repeated mirtazapine administration increases BDNF mRNA levels; moreover, it indicates that the enhancement of BDNF gene expression may be essential for the clinical effect of mirtazapine.
Journal of physiology and pharmacology: an official journal of the Polish Physiological Society 01/2006; 56(4):661-71. · 2.27 Impact Factor
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ABSTRACT: Major depression is frequently associated with the hyperactivity of the hypothalamic-pituitary-adrenocortical axis, and glucocorticoid synthesis inhibitors have been shown to exert antidepressant action. The aim of the present study was to examine the effect of joint administration of metyrapone (50 mg/kg) and imipramine (5 and/or 10 mg/kg) on immobility time, plasma corticosterone concentration, the weight of spleens and thymuses and the proliferative activity of splenocytes in rats subjected to the forced swimming test--an animal model of depression. Metyrapone alone (50 mg/kg) reduced the immobility time of rats in the forced swimming test and decreased plasma corticosterone level, but did not change immunological parameters. Joint administration of metyrapone and imipramine (5 and 10 mg/kg) produced a more pronounced antidepressant-like effect than either of the drugs given alone. The forced swimming procedure significantly increased the proliferative activity of splenocytes, that parameter being reduced only by co-administration of metyrapone and imipramine. Joint administration of metyrapone and imipramine inhibited to a similar extend the corticosterone level as did treatment with metyrapone alone (about twofold); however, the plasma corticosterone level in animals treated with metyrapone and the higher dose of imipramine did not differ from the concentration of this steroid in control, not-stressed rats. The obtained results indicate that metyrapone potentiates the antidepressant-like activity of imipramine and exerts a beneficial effect on the stress-induced increase in plasma corticosterone concentration and the proliferative activity of splenocytes. These finding suggest that a combination of metyrapone and an antidepressant drug may be useful for the treatment drug-resistant depression and/or depression associated with a high cortisol level.
Journal of physiology and pharmacology: an official journal of the Polish Physiological Society 04/2005; 56(1):49-61. · 2.27 Impact Factor
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ABSTRACT: Sigma (sigma) receptors, first defined as a subclass of opioid receptors, later confounded with the high affinity phencyclidine (PCP) binding sites, now are regarded as unique binding sites, distinct from opiate and PCP receptors, and related to higher brain function. The investigation of functional significance of sigma receptors in the brain has been hampered for many years by relative lack of specific tool drugs and by the unavailability of their coherent classification into postulated agonists and antagonists. However, a potential involvement of sigma receptors in psychotic disorders was first suggested soon after their discovery. The sigma receptors are classified into two subtypes, sigma (1) and sigma (2) receptors, of which the first was recently cloned from rodent and human tissues while the second has not yet been fully characterized. Although the precise mechanism of the functional response of these receptors is still uncertain, it is accepted that sigma receptors can modulate a number of central neurotransmitter systems, including noradrenergic, glutamatergic and dopaminergic ones. The sigma receptors have been postulated to be involved in numerous pharmacological and physiological functions, including motor disorders, psychotic disorders, neuroprotective mechanisms. In the last years, a number of compounds with a high affinity and selectivity for sigma binding sites have been discovered and investigated for their therapeutic potential. In this review, we try to summarize the behavioral effects of sigma receptor ligands that have been described, and their activity in animal models related to some brain disorders, especially schizophrenia and affective disorders.
Pharmacopsychiatry 12/2004; 37 Suppl 3:S183-8. · 2.07 Impact Factor
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ABSTRACT: In this study we investigated the effect of imipramine, citalopram and mianserin on behavioural effects of methoxamine, an α1-adrenoceptor agonist, in the rat. Methoxamine (25 and 50 m̈g) given into the brain lateral ventricle, increases the exploratory activity assessed in the open field test (time of walking, ambulatory activity, rearing + peeping). The studied antidepressants, administered repeatedly (10 mg/kg p.o., twice daily, 14 days) but not in single doses, enhance the above effects of methoxamine. The results provide further arguments for the hypothesis that antidepressant drugs administered repeatedly induce a functional α1-adrenoceptor up-regulation.
Human Psychopharmacology Clinical and Experimental 10/2004; 4(1):65 - 70. · 2.48 Impact Factor
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ABSTRACT: The effect of non-competitive (MK-801:/+/-5-methy-10,11-dihydro-5H-dibenzo [a, d] cyclohepten-5,10-imine hydrogen maleate) and competitive (CGP 37849: DL-/E/-2-amino-4-methyl-5-phosphono-3-pentenoic acid) NMDA receptor antagonists on the catalepsy induced by neuroleptics in mice was studied. MK-801 and CGP 37849 antagonized the catalepsy induced by haloperidol, spiperone and fluphenazine. (+)-Cycloserine, a partial glycine agonist, reversed the anticataleptic effect of CGP 37849, but not that of MK-801. The above results indicate that the anticataleptic activity of both these NMDA receptor antagonists is induced by an indirect activation of the dopamine system. The results provide further evidence that competitive NMDA receptor antagonists may be a new class of antiparkinsonian drugs.
Human Psychopharmacology Clinical and Experimental 10/2004; 8(6):433 - 437. · 2.48 Impact Factor
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ABSTRACT: The aim of the present study was to examine SA4503 [1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl)piperazine dihydrochloride], a novel selective receptor agonist, in respect of its potential antidepressant action. To this end we used a forced swimming test in rats to study SA4503 alone, as well as its interaction with imipramine, a classic tricyclic antidepressant. SA4503 decreased the immobility time in the forced swimming test in rats (although only at one of the three doses used); at the same time it did not change the locomotor activity recorded under the same experimental conditions. Moreover, SA4503 showed a synergistic effect with imipramine in the forced swimming test (both those compounds given jointly decreased the immobility time, but were ineffective when administered separately). It had previously been shown that repeated administration of antidepressants with different pharmacological profiles enhanced the action of D-amphetamine, quinpirole and other dopamine stimulants. SA4503 administered repeatedly increased the locomotor hyperactivity induced by D-amphetamine and quinpirole (a dopamine D /D receptor agonist), but not by (+/-)-7-hydroxy-dipropyloamino-tetralin hydrobromide [(+/-)-7-OH-DPAT; a dopamine D receptor agonist]. The results presented in this paper support the suggestion that SA4503 may have potential antidepressive properties.
Behavioural Pharmacology 12/2002; 13(7):537-43. · 2.72 Impact Factor
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ABSTRACT: Tianeptine (TIA) is an antidepressant drug that has been shown to decrease extracellular serotonin level and reveals no affinity for neurotransmitter receptors. The present study was aimed at determining whether repeated TIA treatment induced any adaptive changes in the central dopamine D(2)/D(3) system (behavioural and biochemical) similar to those reported earlier for tricyclic antidepressants. Experiments were carried out on male Wistar rats. TIA was administered at a dose of 5 and 10 mg/kg once or repeatedly (twice daily for 14 days). Fluoxetine (FLU), used as a reference compound, was also administered at a dose of 10 mg/kg. The results obtained showed that TIA or FLU administered repeatedly increased the hyperlocomotion induced by D-amphetamine and 7-hydroxy-dipropylaminotetralin (7-OH-DPAT). Biochemical study revealed a decrease in the [(3)H]7-OH-DPAT binding sites after acute and repeated treatment with TIA or FLU in the islands of Calleja minor, as well as in the shell part of nucleus accumbens septi. On the other hand, both TIA and FLU administered repeatedly increased the binding of [(3)H]quinpirole (a D(2)/D(3) receptor agonist) in the nucleus caudatus as well as in the core part of the nucleus accumbens septi. Similar effects have been observed when dopamine D(2)/D(3) receptors were visualized with the use of [3H]raclopride, a dopamine D(2)/D(3) receptor antagonist. However, TIA and FLU induced a decrease in the level of mRNA encoding for dopamine D(2) receptors, not only after repeated but also after acute treatment. These results indicate that repeated TIA and FLU administration induces adaptive changes in the dopaminergic D(2)/D(3) system and especially enhances the functional responsiveness of dopamine D(2) and D(3) receptors. However, the question of whether this increased responsiveness is important for clinical antidepressant efficacy remains open.
Behavioural Pharmacology 04/2002; 13(2):127-38. · 2.72 Impact Factor
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ABSTRACT: Tianeptine (TIA) is an antidepressant drug which enhances the reuptake of serotonin but, in contrast to tricyclics, shows no affinity for neurotransmitter receptors. The present study was aimed at determining whether repeated TIA treatment induced adaptive changes in the alpha(1)-adrenergic system, similar to those reported by us earlier for tricyclic antidepressants. The experiments were carried out on male mice and rats. TIA was administered at a dose of 5 or 10mg/kg once or repeatedly (twice daily for 14 days) and fluoxetine (FLU), used as a reference compound, at a dose of 10mg/kg. The obtained results showed that TIA administered repeatedly potentiated the methoxamine- and phenylephrine (PHEN)-induced exploratory hyperactivity in rats and clonidine-induced aggressiveness in mice, the effects mediated by alpha(1)-adrenoceptors. TIA given repeatedly (but not acutely) increased the binding (B(max)) of alpha(1)-adrenergic receptors in cerebral cortex for [(3)H]prazosin. However, the ability of the alpha(1)-adrenoceptor agonist PHEN to compete for these sites was not significantly changed. The above results indicate that repeated TIA administration increases the responsiveness of the alpha(1)-adrenergic system (behavioural and biochemical changes). On the other hand, FLU did not affect any behavioural and biochemical changes in this system.
Neuropharmacology 10/2001; 41(3):360-8. · 4.81 Impact Factor
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ABSTRACT: The paper examined the effect of 7-OH-DPAT (7-hydroxy-N,N-di-n-propyl-2-aminotetralin), a dopamine D3 receptors-prefering agonist, on the catalepsy evoked by reserpine, haloperidol and fluphenazine in rats (male Wistar), as well as the influence of nafadotride, a dopamine D3 receptors-prefering antagonist, on that effect. The obtained results show that 7-OH-DPAT, as well as L-DOPA, a drug of choice in the therapy of Parkinson's disease, used for comparison, antagonize the catalepsy induced by reserpine, haloperidol and fluphenazine. Nafadotride, used in a dose (0.2 mg/kg) which inhibits the 7-OH-DPAT-evoked locomotor hyperactivity but does not affect the hypermotility induced by amphetamine and quinpirole, antagonizes the anticataleptic effect of 7-OH-DPAT or L-DOPA. It is therefore assumed that dopamine D3 receptors are involved in the anticataleptic effect of both 7-OH-DPAT and L-DOPA.
Acta Neurovegetativa 02/1999; 106(11-12):1063-73. · 2.73 Impact Factor
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ABSTRACT: Trimipramine (TRI), which shows a clinical antidepressant activity, is chemically related to imipramine but does not inhibit the reuptake of noradrenaline and 5-hydroxytryptamine, nor does it induce beta-adrenergic down-regulation. The mechanism of its antidepressant activity is still unknown. The aim of the present study was to find out whether TRI given repeatedly was able to induce adaptive changes in the dopaminergic and alpha1-adrenergic systems, demonstrated by us previously for various antidepressants. TRI was given to male Wistar rats and male Albino Swiss mice perorally twice daily for 14 days. In the acute experiment TRI (given i.p.) does not antagonize the reserpine hypothermia in mice and does not potentiate the 5-hydroxytryptophan head twitches in rats. TRI given repeatedly to rats increases the locomotor hyperactivity induced by d-amphetamine, quinpirole and (+)-7-hydroxy-dipropyloaminotetralin (dopamine D2 and D3 effects). The stereotypies induced by d-amphetamine or apomorphine are not potentiated by TRI. It increases the behaviour stimulation evoked by phenylephrine (given intraventricularly) in rats, evaluated in the open field test as well as the aggressiveness evoked by clonidine in mice, both these effects being mediated by an alpha1-adrenergic receptor. It may be concluded that, like other tricyclic antidepressants studied previously, TRI given repeatedly increases the responsiveness of brain dopamine D2 and D3 (locomotor activity but not stereotypy) as well as alpha1-adrenergic receptors to their agonists. A question arises whether the reuptake inhibition is of any importance to the adaptive changes induced by repeated antidepressants, suggested to be responsible for the antidepressant activity.
Acta Neurovegetativa 02/1998; 105(2-3):329-42. · 2.73 Impact Factor
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ABSTRACT: Trimipramine (TRI), which shows a clinical antidepressant activity, is chemically related to imipramine but does not inhibit
the reuptake of noradrenaline and 5-hydroxytryptamine, nor does it induce β-adrenergic down-regulation. The mechanism of its
antidepressant activity is still unknown. The aim of the present study was to find out whether TRI given repeatedly was able
to induce adaptive changes in the dopaminergic and α1-adrenergic systems, demonstrated by us previously for various antidepressants. TRI was given to male Wistar rats and male
Albino Swiss mice perorally twice daily for 14 days.
In the acute experiment TRI (given i.p.) does not antagonize the reserpine hypothermia in mice and does not potentiate the
5-hydroxytryptophan head twitches in rats. TRI given repeatedly to rats increases the locomotor hyperactivity induced by d-amphetamine,
quinpirole and (±)-7-hydroxy-dipropylo-aminotetralin (dopamine D2 and D3 effects). The stereotypies induced by d-amphetamine or apomorphine are not potentiated by TRI. It increases the behaviour
stimulation evoked by phenylephrine (given intraventricularly) in rats, evaluated in the open field test as well as the aggressiveness
evoked by clonidine in mice, both these effects being mediated by an α1-adrenergic receptor.
It may be concluded that, like other tricyclic antidepressants studied previously, TRI given repeatedly increases the responsiveness
of brain dopamine D2 and D3 (locomotor activity but not stereotypy) as well as α1-adrenergic receptors to their agonists. A question arises whether the re-uptake inhibition is of any importance to the adaptive
changes induced by repeated antidepressants, suggested to be responsible for the antidepressant activity.
Acta Neurovegetativa 01/1998; 105(2):329-342. · 2.73 Impact Factor
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ABSTRACT: Pramipexole (SND 919; 2-amino-4,5,6,7-tetrahydro-6-propyl-amino-benzthiazole-dihydroc hlo ride) is a novel dopamine D2 family receptor agonist with a predominant action on D2 autoreceptors and with some D3 vs. D2 receptor preference. The central behavioural effects of pramipexole given subcutaneously to rats (male Wistar) and mice (Albino Swiss) are presented in this paper. Used in low doses (0.001-0.1 mg/kg), pramipexole induced locomotor hypoactivity which was antagonized by a low dose of spiperone; at higher doses (0.3, 1 mg/kg) it evoked hyperactivity which was inhibited by haloperidol, sulpiride and clozapine, but not by SCH 23390 (R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3- benzazepine hydrochloride). Pramipexole (0.1-1.0 mg/kg) antagonized the akinesia induced by combined pretreatment with reserpine (5 mg/kg) and alpha-methyl-p-tyrosine (250 mg/kg). Pramipexole (0.1-1 mg/kg) potentiated the hyperkinetic effect of L-DOPA (L-3,4-dihydroxyphenylalanine) (50 and 200 mg/kg, together with benserazide, 50 mg/kg) in naive and monoamine-depleted (reserpine + alpha-methyl-p-tyrosine) rats. The higher doses of pramipexole (1 and 3 mg/kg) evoked stereotypy which was antagonized by pretreatment with sulpiride or clozapine. The catalepsy induced by haloperidol, spiperone or fluphenazine was antagonized by pramipexole (1-3 mg/kg). Pramipexole (1 mg/kg) induced hypothermia in mice, which was antagonized by sulpiride. The obtained results indicate that pramipexole: (i) at low doses stimulates the dopamine D2 presynaptic autoreceptors; (ii) at higher doses stimulates dopamine D2 postsynaptic receptors. An effect on the dopamine D3 receptor cannot be excluded. At low doses pramipexole may have antipsychotic activity, and at higher ones antiparkinsonian activity.
European Journal of Pharmacology 05/1997; 324(1):31-7. · 2.52 Impact Factor
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ABSTRACT: Roxindole (ROX) (EMD 49980, 5-hydroxy-3-[4-(4-phenyl-1, 2,3,6-tetrahydropyridyl(1))-butyl(1)]-indole, mesylate), a potent selective agonist of presynaptic dopamine receptors with clinical antipsychotic and antidepressant activity, was studied pharmacologically in rats (male Wistar) and mice (male Albino Swiss) with respect to its influence on the central 5-hydroxytryptamine (5-HT) system. ROX did not induce the 5-HT1A syndrome (flat body and forepaw treading) in rats, but partly antagonized the syndrome evoked by 8-OH-DPAT. The 8-OH-DPAT-induced hypothermia in mice (a 5-HT1A effect) was not inhibited by ROX. The drug evoked hypothermia, which was antagonized by pindolol, but not by (+)-WAY-100135. ROX did not inhibit the m-chlorophenylpiperazine-induced hypothermia in mice (a 5-HT1B effect), or the exploratory hypoactivity in rats (a 5-HT1C effect). Head twitches induced by a low dose of L-5-HTP were potentiated by ROX, whereas those induced by its higher dose were antagonized. ROX also antagonized the hyperthermia induced by fenfluramine or trifluoromethylphenylpiperazine at a high ambient temperature in rats (a 5-HT2A effect). The results obtained indicate that ROX inhibits 5-HT uptake and shows 5-HT2A antagonistic and probably a 5-HT1B agonistic activities.
Pharmacopsychiatry 04/1997; 30(2):55-61. · 2.07 Impact Factor
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ABSTRACT: Pramipexole (2-amino-4,5,6,7-tetrahydro-6-propyl-amino-benzthiazole-dihydrochl oride), a new dopamine receptor agonist with preference for D3 compared to D2 and D4 receptors, was tested in rats in respect of its potential antidepressant activity. In the forced swimming test the drug under study, given three times in rats, reduced the immobility time. In the forced swimming test, joint treatment with antidepressants (imipramine, amitriptyline) and pramipexole evoked a more potent effect than any of the drugs given alone; however, the locomotor hyperactivity was weaker after joint administration. Citalopram and fluoxetine, inactive per se in the forced swimming tests, visibly enhanced the antidepressant-like effect of pramipexole but, on the other hand, they attenuated the locomotor hyperactivity evoked by the drug. Repeated treatment with pramipexole (0.3 or 1 mg/kg, twice daily for 14 days) increased the locomotor activity measured at 1 h after the last dose. Repeated administration of pramipexole (as above) potentiated the D-amphetamine- or quinpirole-induced locomotor hyperactivity. The obtained results indicate that, in the tests used, pramipexole evokes effects similar to those of typical antidepressants and, at the same time, enhances their activity (the forced swimming test in rats); therefore it may be regarded as a potential antidepressant drug.
Acta Neurovegetativa 02/1997; 104(4-5):525-33. · 2.73 Impact Factor
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ABSTRACT: EMD 57445 ((S)-(-)-[4-hydroxy-4-(3,4-benzodioxol-5-yl) -piperidin-1-ylmethyl]-3-(4-methoxyphenyl)-oxazolidin- 2-one) is a new sigma receptor ligand with only marginal affinity for many other (including dopamine) receptors. In the present study, central, particularly neuroleptic-like, effects of this compound were evaluated and compared with those of another sigma receptor ligand, rimcazole. EMD 57445 decreased locomotor activity in rats and mice. The amphetamine-induced locomotor hyperactivity and stereotypy were reduced by EMD 57445. The drug was able to inhibit the behavioural effects induced by apomorphine, i.e., the locomotor hyperactivity, stereotypy and aggression in rats, as well as climbing in mice. The hyperlocomotion induced by quinpirole (a dopamine D2/3 receptor agonist) and the grooming induced by SKF 38393 (a dopamine D1 receptor agonist) were decreased by EMD 57445. The behavioural stimulation evoked in rats by non-competitive (MK-801, (+)-5-methyl-10,11-dihydroxy-5H-dibenzo (a,b)-cyclohepten-5,10-imine hydrogen maleate) or competitive (CGP 37849, D,L-E-amino-4-methyl-5-phosphono-3-pentenoic acid) NMDA receptor antagonists was also inhibited. EMD 57445 decreased the cocaine-, morphine- or caffeine-induced locomotor hyperactivity in rats or mice. It neither induced catalepsy nor increased muscle tone in rats. Rimcazole had somewhat different effects: it increased the amphetamine stereotypy as well as the amphetamine-, quinpirole- and cocaine-induced locomotor hyperactivity in rats. The results indicate that EMD 57445 shows functional antidopaminergic activity and may be useful as an antipsychotic drug devoid of extrapyramidal side-effects.
European Journal of Pharmacology 12/1996; 315(3):235-43. · 2.52 Impact Factor
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ABSTRACT: Effects of paroxetine (10 mg/kg PO, twice daily, 14 days) on 5-HT receptor subpopulations in the brain were evaluated pharmacologically, electrophysiologically and biochemically in male Wistar rats. Imipramine was used for comparison. Repeated paroxetine antagonized the 8-OH-DPAT-induced behavioural syndrome (a 5-HT1A effect); imipramine showed similar, yet weaker, activity. The 5-HT-or 8-OH-DPAT-induced inhibition of population spikes in hippocampal slices was increased by both those repeated antidepressants. Repeated (or acute) paroxetine decreased the density of and increased the affinity for 5-HT1A receptors ([3H]-8-OH-DPAT used as ligand) in the hippocampus, while imipramine induced opposite effects. m-Chlorophenyl piperazine (m-CPP)-evoked exploratory hypoactivity, a 5-HT2C effect, was reduced by repeated paroxetine, but not by imipramine. Either of the antidepressants given repeatedly antagonized TFMPP-induced hyperthermia (another putative 5-HT2C effect). 5-HTP-induced head twitches (a 5-HT2A effect) were inhibited by repeated paroxetine or imipramine. Either antidepressant given repeatedly decreased the density of 5-HT2A receptors ([3H]-ketanserin as a ligand) in the brain cortex, but did not change their affinity. The present results indicate that paroxetine given repeatedly induces secondary changes in 5-HT2 receptors, which lead to reduction of the 5-HT2 neurotransmission (reduced responsiveness of 5-HT2 postsynaptic receptors). The consequences of the secondary changes in 5-HT1A receptors, found here still await clarification.
Psychopharmacologia 10/1996; 127(1):73-82. · 4.08 Impact Factor
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ABSTRACT: The effects of antidepressants given in a single dose or repeatedly (10 mg/kg p.o., twice daily, 14 days) on binding to dopamine D2 receptors in the striatum and limbic forebrain of Wistar male rats were studied. [3H]N-0437, (2-(N[2,3(n)-3H]propyl-N-(2-thiofuranyl)-2'-ethylamino) -5-hydroxy-1,2,3,4-tetrahydronaphthalene), a dopamine D2 receptor agonist, was used as a ligand. Already a single dose of imipramine and fluoxetine caused a statistically significant decrease in the affinity of the ligand for dopamine D2 receptors in the striatum, but only at 72 h after drug administration. Also at 72 h after the single dose of mianserin a significant increase in the density of dopamine D2 receptors was observed. Repeated imipramine, amitriptyline and mianserin increased the affinity for dopamine D2 receptors in the striatum and in the limbic forebrain. Repeated fluoxetine increased that affinity in the striatum, but decreased it in the limbic forebrain. The density of dopamine D2 receptors was increased by the repeated administration of the antidepressants studied in the limbic forebrain, but was not changed in the striatum. The results obtained in the present study are in good agreement with the previously reported enhancement of behavioural responsiveness to dopamine and dopamine stimulants (dopamine D2 up-regulation) evoked by repeated treatment with antidepressants.
European Journal of Pharmacology 06/1996; 304(1-3):49-54. · 2.52 Impact Factor
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ABSTRACT: Roxindole (EMD 49980, 5-hydroxy-3-[4-(4-phenyl-1,2,3,6-tetrahydropyridyl(1))-butyl(1)]-indole mesylate), a selective dopamine autoreceptor agonist and a potential antipsychotic drug, shows a clinical antidepressant efficacy. The present paper examined the neuropharmacological profile of roxindole in rats (male Wistar) and mice (male Albino Swiss) in respect of its influence on dopamine system. Used in low doses, roxindole decreased the locomotor activity, but in higher ones it did not induce a locomotor hyperactivity or stereotypy. It antagonized the amphetamine-induced hyperlocomotion, the amphetamine- or apomorphine-induced stereotypy, apomorphine climbing behaviour and reserpine-induced akinesia. The quinpirole-induced hyperlocomotion was inhibited by roxindole. When given alone, the drug in question, did not induce the catalepsy, but antagonized the catalepsy induced by haloperidol, spiperone and fluphenazine. The immobility time in the forced swimming test was reduced. Like typical antidepressants, roxindole given repeatedly (twice daily, 14 days) increased the hyperlocomotion induced by D-amphetamine. The results described above indicate that roxindole may have an antidepressant and antiparkinsonian activity and should be devoid of extrapyramidal side-effects.
Acta Neurovegetativa 02/1996; 103(5):627-41. · 2.73 Impact Factor
