Neurophysiological analysis of sleep regulation mechanism through the basal ganglion-pontine tegmental systems

点击翻译按钮获取中文摘要

The pontine tegmental area has a crucial role in regulation of REM sleep and wakefulness. The basal ganglia is, projecting to the pontine tegmental area, involved in motor regulation or regulation of muscular tonus. The orexinergic system in the hypothalamus project to the basal ganglia (substantia nigra pars reticulata : SNr) or the pontine tegmentum and regulate the various events during sleep and wakefulness. The present study was performed to elucidate the sleep regulation mechanisms especially the relation of muscular tonus regulation mediated by the hypothalamic-basal ganglia axis. The results obtained are ;1.In decebrated cats, activation of the SNr by orexin injection increased or maintained the muscular tonus level ; muscular atonia induced by the electrical stimulation to the pedunculopontine tegmental nucleus (PPN) was suppressed after the orexin injection to the SNr. The orexin effect was blocked by bicuculline (GABA_A receptor antagonist). The same effect was obtained when orexin was injected to the PPN. These results suggest that the GABAergic neurons in the SNr or the GABAergic interneurons in the PPN regulate the muscular tonus by suppressing the PPN neurons that initiate muscular atonia.2.When orexin was injected to the PPN in free moving rats, GABA release measured by microdialysis method increased. The result supports the hypothesis that the there is a tonic GABAergic inhibition on the PPN neurons that is mediated by the orexinergic influence to the SNr or PPN.3.The GABAergic neurons in the SNr showed higher activity during wakefulness or bpoth wakefulness and REM sleep. These neurons are candidates of the GABAergic input to the PPN that suppress the atonia inducing system in the PPN during wakefulness.