RESUMO
6-Hydroxydopamine (6-OHDA) injected into the lateral cerebral ventricles of rats impaired their exercise performance until exhaustion (treadmill run and swimming). The injected rats displayed significantly less training-induced improvement of swimming performance than did the control animals. Reduced performance also was seen in adult rats treated intraperitoneally with 6-OHDA in the neonatal or adult periods. The functional impairment can be explained by the neurotoxic action of 6-OHDA on monoamine brain structures (substantia nigra and locus ceruleus) and/or on peripheral sympathetic innervation, the latter assessed by histofluorescence of the iris muscle. The possible contribution of lacticacidemia to the reduced tolerance to stress of 6-OHDA-treated rats by the intracerebroventricular route also is considered.
Assuntos
Hidroxidopaminas/farmacologia , Esforço Físico/efeitos dos fármacos , Adaptação Fisiológica , Medula Suprarrenal/fisiologia , Animais , Hidroxidopaminas/administração & dosagem , Injeções Intraperitoneais , Injeções Intraventriculares , Masculino , Oxidopamina , Ratos , Ratos Endogâmicos , Natação , Sistema Nervoso Simpático/fisiologiaRESUMO
An injection of 250 micrograms 6-OHDA into the right cerebral ventricle of adult rats tested after 45 days led to a reduction of the run performance on the treadmill compared with the control group, but only in the first period of this test, repeated 10-11 times, every 2-3 days. This behavior was more obvious in male and in exercise-enduring rats. The histological examination proved partial destruction of central monoaminergic (especially dopaminergic) structures in the 6-OHDA treated rats. 24-48 hours after peripheral injections of 6-OHDA (100 mg/kg b. w.) a considerable reduction of the run and swim performance (acute exercise till exhaustion) occurred. Falck's histofluorescence method proved large destructions of the noradrenergic innervation in the iris; 6-OHDA injected i.p. into neonatal rats had similar effects.
Assuntos
Hidroxidopaminas/farmacologia , Atividade Motora/efeitos dos fármacos , Esforço Físico/efeitos dos fármacos , Animais , Feminino , Injeções Intravenosas , Injeções Intraventriculares , Masculino , Ratos , Corrida , NataçãoRESUMO
In rats injected in the cerebral ventricle with 250 micrograms of 6-hydroxydopamine a significant blockade of the improvement of swimming performance due to training occurs. The central injection of 6-OHDA leads to a lengthening of the total latency time (LT) of active conditioned reaction in shuttle box and of the LT of netative escape responses during learning, but not of the positive avoidance responses. 6-OHDA injected after the learing schedule (12 days) has no effect on the LT during relearning and extinction. Therefore a partial destruction of central monoaminergic, and especially of dopaminergic, neurons impairs particularly the acquisition but not the retention of the motor program.