RESUMO
The study attempted to evaluate the influence of hormonal status (gender and oestrous cycle) on learning in male and female rats and to determine whether this difference was affected by dopamine agonists (cocaine and amphetamine). Rats were exposed to foot-shocks in a Y-maze. Exploratory and avoidance behaviours were tested on two trials, 24 hours following conditioning (Trial 1) and 2 weeks subsequently (Trial 2). Amphetamine (1mg/kg/ml) stimulated exploratory behaviour, whereas cocaine (1mg/kg/ml) had a depressant effect at Trial 1. Avoidance learning of a potentially dangerous environment was significantly less in oestrous than in diestrous and male rats. These results provide evidence that hormonal status influences learning. Cocaine and amphetamine given in a single low doses did not produce any significant effects on avoidance learning(AU)
Assuntos
Ratos , 21003 , Aprendizagem/efeitos dos fármacos , Anfetamina/farmacologia , Cocaína/farmacologia , Aprendizagem da Esquiva/efeitos dos fármacosRESUMO
This study was designed to evaluate the hypothesis that the mesolimbic dopamine pathways are involved in the manifestations of psychotic symptoms. Rats were injected with amphetamine (5.0 mg/kg) and apomorphine (1.0 mg/kg) following bilateral lesions of the nucleus accumbens. The results showed high levels of stereotypy following amphetamine administrations in contrast to the low levels seen after the administration of apomorphine. These results, in conjunction with previous experiments involving the globus pallidus, were evaluated in terms of the accumbens' influence on drug-induced psychosis (AU)
Assuntos
21003 , Masculino , Ratos , Anfetamina/farmacocinética , Apomorfina/farmacocinética , Eletrochoque , Núcleo Accumbens , Núcleos Septais , Comportamento Estereotipado/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ratos EndogâmicosRESUMO
The neuropharmacological model used in this study has indicated that hyperactivity in rats results from cholinergic overactivity due to increased brain acetysholine level. Support for this contention comes from the fact that the hyperactivity induced in rats is significantly (P<0.001) attenuated by a cholinergic antagonist-atropine sulphate. Whatever the complexities of the receptor mechanisms, this observation has clear implications both for our understanding of the etiology of hyperkinesia and its treatment. In addition, the fact that chemical methods of treatment clearly ameliorate the syndrome has supported the belief that hyperkinesia is primarily a biologic rather than a psychological disorder. However, experimental animals are not humans and it is therefore quite possible that drugs have effects in man which are different from those in rats. Thus, obvious caution must be used in applying these results and those of other experiments to the understanding of hyperkinesia. Nevertheless, the results presented in this study suggest that anticholinergics might be useful chemotherapy for hyperkinesia (AU)
Assuntos
Ratos , 21003 , Hipercinese/tratamento farmacológico , Transtorno do Deficit de Atenção com Hiperatividade , Fisostigmina/farmacocinética , Atropina , Neostigmina , Cloreto de Sódio , Reserpina , Tranilcipromina , Haloperidol , Dissulfeto de Bis(4-Metil-1-Homopiperaziniltiocarbonila) , Anfetamina/farmacocinéticaRESUMO
Spontaneous motor activity of preweanling rats (14-day-old) was examined in an activity cage following the administration of atropine at 1.0, 2.5, 5.0, and 10.0 mg/kg respectively. Compared with saline-control animals, atropine at these dosages, did not significantly affect the activity level of the 14-day-old rat. The motor activity of 14-20-day-old rats was also measured following the administration of atropine (10mg/kg) in the Y-maze and the activity cage. The activity level was significantly decreased in (a) all ages in Y-maze and (b) the 18-day-old animals only in the activity cage. In contrast, amphetamine (2.0, 4.0, and 10.0 mg/kg) induced significant increments in spontaneous motor activity. It is suggested that a cholinergic mechanism concerned with the modulation of central nervous system arousability becomes functional at 18 days of age, that is, subsequent to a more caudal arousal inducing mechanism, which seems to be mediated by a catecholaminergic system (AU)
Assuntos
Ratos , 21003 , Atividade Motora/efeitos dos fármacos , Receptores Colinérgicos , Atropina/farmacocinética , Anfetamina/farmacocinéticaRESUMO
An attempt was made to indicate the neuropharmalogical relationship between Parkinson's disease, Huntington's chorea, tardive dyskinesia and Attentional Deficit Disorder. In the case of the latter, an experimental model has been prersented indicating cholinergic dysfunction in the nigro-striatal pathway. Postulates are proposed which will enable us to understand the many factors responsible for these clinical states. (AU)