Veratrine blocks the lamotrigine-induced swimming increase and immobility decrease in the modified forced swimming test.

Lamotrigine exhibits an anti-immobility effect in the modified forced swimming test, increasing swimming and climbing, behaviors that are related to serotonergic and noradrenergic effects, respectively. However, these effects could be secondary to lamotrigine blockade of Na(+) sensitive channel. Thus, this study investigated the influence of veratrine (0.1 mg/kg, ip, 10 min before each lamotrigine administration), an Na(+) channel activator, in the effect of lamotrigine (20 mg/kg, ip, 24, 5, 1 h before the test session) in the modified forced swimming test. Veratrine pre-treatment blocked lamotrigine-induced immobility decrease and swimming increase but it did not change the effect of lamotrigine on climbing. These results suggest that the serotonergic effect of lamotrigine in the modified forced swimming test is dependent on Na(+) voltage sensitive channel blockade, whereas its noradrenergic effect is not.

The nonsteroidal antiinflammatory drug piroxicam reverses the onset of depressive-like behavior in 6-OHDA animal model of Parkinson's disease.

Depression is one of the most common psychiatric symptoms in patients with Parkinson's disease (PD). Some authors have reported that depression is characterized by activation of the inflammatory response. Animal models of PD also present with depressive-like behavior, such as increased immobility time in the modified forced swim test and anhedonia-like behavior in the sucrose preference test. Considering the potential neuroprotective effect of nonsteroidal antiinflammatory drugs in neurodegenerative diseases, the objective of the present study was to investigate the effects of piroxicam on depressive-like behavior in male Wistar rats lesioned with 6-hydroxydopamine (6-OHDA) in the substantia nigra (SN). Antidepressant-like effects were observed after prolonged administration of piroxicam for 21days. In the forced swim test, the 6-OHDA+saline group exhibited significant reductions in swimming time and increased immobility time compared with the sham+saline. In the sucrose preference test, the 6-OHDA+piroxicam group exhibited no reduction of sucrose preference compared with the sham+saline, with significant effects of treatment and time and a significant treatment×time interaction. 5-Hydroxytryptamine (5-HT) levels significantly decreased in the hippocampus in the 6-OHDA+saline group and not changed in the 6-OHDA+piroxicam group when compared with the sham+saline on day 21. In conclusion, 21-day treatment with piroxicam reversed the onset of depressive-like behavior and prevented the reduction of hippocampal 5-HT levels.

Monosialoganglioside (GM1) attenuates the behavioural effects of long-term haloperidol administration in supersensitive rats.

In the present study we investigated the effects of co-administration of GM(1) (15.0 mg/kg, twice daily, for 30 days) and haloperidol (1.0 mg/kg, twice daily, for 30 days), as well as the effects of a 5-day treatment with this dose of GM(1) after withdrawal from haloperidol in rats. The animals were evaluated in the open-field test and apomorphine-induced stereotyped behaviour. The results show that GM(1) was able to attenuate dopaminergic supersensitivity evaluated by the locomotion frequency at 24 and 48 h after the withdrawal from haloperidol. On the other hand, rearing frequency was changed neither by haloperidol nor by GM(1.) In haloperidol-treated rats immobility time differs from 30 min observation session in comparison with the following sessions after the withdrawal from neuroleptic. Apomorphine-induced stereotyped behaviour produced a significant increase in scores of haloperidol-withdrawn rats. GM(1) did not modify the haloperidol effects and did not change the dopamine receptor affinity to apomorphine 100 h from abrupt neuroleptic withdrawal.

Reliability and clinical utility of a Portuguese version of the Abnormal Involuntary Movements Scale (AIMS) for tardive dyskinesia in Brazilian patients.

The objective of the present study was to evaluate the reliability and clinical utility of a Portuguese version of the Abnormal Involuntary Movements Scale (AIMS). Videotaped interviews with 16 psychiatric inpatients treated with antipsychotic drugs for at least 5 years were evaluated. Reliability was assessed by the intraclass correlation coefficient (ICC) between three raters, two with and one without clinical training in psychopathology. Clinical utility was assessed by the difference between the scores of patients with (N = 11) and without (N = 5) tardive dyskinesia (TD). Patients with TD exhibited a higher severity of global evaluation by the AIMS (sum of scores: 4.2 +/- 0.9 vs 0.4 +/- 0.2; score on item 8: 2.3 +/- 0.3 vs 0.4 +/- 0.2, TD vs controls). The ICC for the global evaluation was fair between the two skilled raters (0.58-0.62) and poor between these raters and the rater without clinical experience (0.05-0.29). Thus, we concluded that the Portuguese version of the AIMS shows an acceptable inter-rater reliability, but only between clinically skilled raters, and that it is clinically useful.

Myricitrin, a nitric oxide and protein kinase C inhibitor, exerts antipsychotic-like effects in animal models.

Myricitrin is a nitric oxide (NO) and protein kinase C (PKC) inhibitor that has central nervous system activity, including anxiolytic-like action. Nitric oxide inhibitors blocked the behavioral effects of apomorphine, suggesting an antipsychotic-like effect. Furthermore, PKC inhibition reduced psychotic symptoms in acute mania patients and blocked amphetamine-induced hyperlocomotion, suggesting a potential antipsychotic-like effect. The present study evaluated the effects of myricitrin in animal models that assess antipsychotic-like effects (apomorphine-induced stereotypy and climbing and the paw test) and extrapyramidal side effects (catalepsy test and paw test). Olanzapine was used as a positive control. 7-Nitroindazole (7-NI), a NOS inhibitor, and l-arginine, a NO precursor, were used to evaluate nitrergic modulation, and tamoxifen was used to test the effect of PKC inhibition. In mice, myricitrin dose-dependently and olanzapine blocked the stereotypy and climbing induced by apomorphine at doses that did not induce catalepsy. 7-Nitroindazole also blocked apomorphine-induced stereotypy and climbing, which were reversed by l-arginine pretreatment. l-arginine only attenuated the effects of myricitrin on apomorphine's effects. Tamoxifen also blocked apomorphine-induced stereotypy and climbing. In the paw test in rats, myricitrin and olanzapine increased hindlimb retraction time at doses that did not affect forelimb reaction time, whereas haloperidol affected both parameters at the same dose. Myricitrin did not induce catalepsy in the bar test. Tamoxifen did not affect hindlimb retraction time or forelimb retraction time, whereas 7-NI significantly increased hindlimb reaction time. Thus, myricitrin exhibited an antipsychotic-like profile at doses that did not induce catalepsy, and this effect may be related to nitrergic action.

Nicotine induces sensitization of turning behavior in 6-hydroxydopamine lesioned rats.

Nicotinic drugs have been proposed as putative drugs to treat Parkinson's disease (PD). In this study, we investigated whether nicotine can sensitize parkinsonian animals to the effect of dopaminergic drugs. Testing this hypothesis is important because nicotine has been shown to present neuroprotective and acute symptomatic effects on PD, but few studies have addressed the question of whether it may induce long-lasting effects on dopamine neurotransmission. We tested this hypothesis in the 6-hydroxydopamine (6-OHDA) rat model of PD. A pretreatment of these rats with 0.1-1.0 mg/kg nicotine induced a dose-dependent sensitization of the turning behavior when the animals were challenged with the dopamine receptor agonist apomorphine 24 h later. In agreement with previous studies, while apomorphine induced contraversive turns, nicotine, as well as amphetamine, induced ipsiversive turns in the 6-OHDA rats. This result suggests that, like amphetamine, nicotine induces turning behavior by promoting release of dopamine in the non-lesioned striatum of the rats. However, it is unlikely that the release of dopamine may also explain the nicotine-induced sensitization of turning behavior. First, the dopamine amount that could be released in the lesioned hemi-striatum by the nicotine pretreatment was minimum-less than 3%, as detected by HPLC-EC. Second, a pretreatment with amphetamine did not induce this behavioral sensitization. A pretreatment with apomorphine-induced sensitization, but it was minimal when compared to that induced by nicotine. Therefore, it is unlikely that the sensitization of the turning behavior induced by nicotine was consequent of the release of dopamine. However, the expression of such sensitization seems to depend on the activation of dopaminergic receptors, since it was seen when the nicotine-sensitized animals were challenged with apomorphine, but not with a second nicotine challenge. These findings are relevant for PD drug therapy since they suggest that the doses of dopaminergic drugs used to treat PD could be reduced if a nicotinic drug were co-administered.

Reliability and clinical utility of a Portuguese version of the Abnormal Involuntary Movements Scale (AIMS) for tardive dyskinesia in Brazilian patients

The objective of the present study was to evaluate the reliability and clinical utility of a Portuguese version of the Abnormal Involuntary Movements Scale (AIMS). Videotaped interviews with 16 psychiatric inpatients treated with antipsychotic drugs for at least 5 years were evaluated. Reliability was assessed by the intraclass correlation coefficient (ICC) between three raters, two with and one without clinical training in psychopathology. Clinical utility was assessed by the difference between the scores of patients with (N = 11) and without (N = 5) tardive dyskinesia (TD). Patients with TD exhibited a higher severity of global evaluation by the AIMS (sum of scores: 4.2 ± 0.9 vs 0.4 ± 0.2; score on item 8: 2.3 ± 0.3 vs 0.4 ± 0.2, TD vs controls). The ICC for the global evaluation was fair between the two skilled raters (0.58-0.62) and poor between these raters and the rater without clinical experience (0.05-0.29). Thus, we concluded that the Portuguese version of the AIMS shows an acceptable inter-rater reliability, but only between clinically skilled raters, and that it is clinically useful