Paraventricular nucleus as a third system of cortical activation

本研究表明，在麻醉后自主呼吸的大鼠脑室旁核（mpPVN）内侧旁细胞细分区微注射多种药物（l -谷氨酸、氰化物、食欲素、组胺等）可引起觉醒/打哈欠反应。为了评估唤醒/打哈欠反应，我们监测了皮质电图（EcoG）、肋间肌电图（EMG）作为吸气活动、二腹肌电图和血压的指标。唤醒/打哈欠反应的特征是EcoG的唤醒转移到更低的电压和更快的节奏，以及一个大的张嘴吸气。由于在mpPVN中微量注射l -谷氨酸引起了典型的觉醒/打哈欠反应，我们认为mpPVN是触发皮层激活的原因。微注射氰化物可引起相同的觉醒/偏航反应，表明mpPVN对PVN内的化学缺氧或缺血敏感。在mpP中微量注射Orexin- a和/或Orexin- b，更多的VN也会引起唤醒/打哈欠反应，表明Orexin的唤醒机制是由mpPVN介导的。将H1组胺能受体注射到mpPVN中也能引起觉醒/打哈欠反应。此外，我们得到了相同的唤醒/打哈欠反应引起的光刺激。较高的光照强度显著降低了觉醒/打哈欠反应的潜伏期。侧脑室注射h1受体拮抗剂预处理，可阻断光刺激引起的觉醒/打哈欠反应，提示脑组织组织能神经传递在调节光诱导的觉醒/打哈欠反应中起作用。在形态学实验中，我们发现反复注射l -谷氨酸诱导频繁打哈欠时，mpPVN中出现c-fos和CRH双染色或c-fos和催产素双染色的细胞。我们假设mpPVN中的CRH细胞负责皮层激活，而催产素能神经元导致打哈欠行为。少

The present study revealed that arousal/yawning response was evoked by microinjections of various agents (L-glutamate, cyanide, Orexin, histamine, etc.) into the medial parvocellular subdivision of the paraventricular nucleus(mpPVN) in an anesthetized, spontaneouly breathing rat. To evaluate arousal/yawning response, we monitored electrocorticogram(EcoG), intercostal electromyogram(EMG) as an index of inspiratory activity, digastric EMG and blood pressure.The arousal/yawning response was characterized by an arousal shift in EcoG to lower voltage and faster rhythms, and a single large inspiration with mouth opening. Since microinjection of L-glutame in mpPVN evoked the typical arousal/yawning response, we concluded that mpPVN is responsible for triggering the cortical activation. The same arousal/yawing response was induced by microinjection of cyanide, indicating that mpPVN is sensitive to chemical hypoxia or ischemia within the PVN. Microinjections of Orexin-A and/or Orexin-B into mpP … More VN also induced the arousal/yawning response, suggesting that arousal mechanism of Orexin is mediated by mpPVN. Microinjection of H1 histerminergic receptor agoinst into mpPVN also elicited the arousal/yawning response. Furthermore, we obtained the same arousal/yawning response was evoked by light stimulation. Higher light intesity significantly reduced the onset latency of the arousal/yawning response. Pretreatment with an H1-receptor antagonist which was injected into the lateral ventricle, blocked the arousal/yawning response induced by light stimulation, suggesting a role of brain histerminergic neurotransmission in modulating the light-induced arousal/yawning response. In morphological experiment, we found those cells which were double-stained by c-fos and CRH or c-fos and oxytocine in the mpPVN, when frequent yawings were induced by repetitive injections of L-glutamete. We hypothesize that CRH cells in mpPVN are responsible for cortical activation, whereas oxytocinergic neurons cause yawning behavior. Less