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

脑桥被盖区在快速眼动睡眠和清醒状态的调节中起着至关重要的作用。基底神经节向脑桥被盖区突出，参与运动调节或肌张力的调节。下丘脑的食欲能系统投射到基底神经节（网状黑质：SNr）或脑桥被，并调节睡眠和清醒时的各种事件。本研究旨在阐明睡眠调节机制，特别是下丘脑-基底神经节轴介导的肌张力调节的关系。得到的结果是：1。在瘦弱的猫中，进食素注射激活SNr增加或维持肌肉张力水平；进食素注射后，电刺激桥脚被盖核（PPN）引起的肌张力失调得到抑制。双球茎碱（GABA_A受体拮抗剂）可阻断食欲素的作用。当向PPN注射促食欲素时，也获得了相同的效果。这些结果表明，SNr中的gaba能神经元或PPN中的gaba能中间神经元通过抑制引发肌肉张力的PPN神经元来调节肌肉张力。自由运动大鼠PPN注射促食欲素后，微透析法测得GABA释放量增加。该结果支持了PPN神经元存在强直性gaba能抑制的假设，这种抑制是通过对SNr或PPN.3的促食能影响介导的。高噪区gaba能神经元在清醒期或清醒期和快速眼动期均表现出较高的活动。这些神经元是gaba能输入PPN的候选神经元，在清醒时抑制PPN中的张力诱导系统。

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.