Yamamoto Tatsuo, Shono Koyo
Department of Anesthesiology, Graduate School of Medicine, Chiba University, Chiba 260-8670.
Masui. 2007 Jan;56(1):40-7.
Orexin-A and orexin-B are hypothalamic peptides and regulate feeding behavior, energy metabolism and the sleep-wake cycle. Orexin-A binds equally to both orexin-1 and orexin-2 receptors, while orexin-B has a preferential affinity for orexin-2 receptors. Orexin-A and orexin-B are concentrated in superficial laminae of the spinal dorsal horn, and orexin-A and orexin-1 receptors are found in the dorsal root ganglion cells. Intravenous injection of orexin-A produces an anti-thermal hyperalgesic effect in the carrageenan test and this effect of orexin-A was mediated by the activation of orexin-1 receptor at the peripheral primary afferent terminal. Intrathecal and intracerebroventricular injection of orexin-A produces an analgesic effect in the formalin test and the carrageenan test and the neuropathic pain models and these effects of orexin-A are thought to be mediated by the activation of orexin-1 receptor. In the isolated spinal cord preparation from 0-to 3-day old rats, a slow depolarizing response induced by single shock stimulation of a dorsal root at C-fiber strength and wind-up phenomenon were effectively attenuated by the application of orexin-A, orexin-B and [Ala11 D-Leu15] orexin-B, a selective orexin-2 receptor agonist. This suggested that, in the neonatal rat spinal cord, orexin-2 receptor, but not orexin-1 receptor, is involved in the nociceptive transmission.
食欲素 -A和食欲素 -B是下丘脑肽，可调节进食行为、能量代谢和睡眠 -觉醒周期。食欲素 -A与食欲素 -1受体和食欲素 -2受体的结合能力相同，而食欲素 -B对食欲素 -2受体具有优先亲和力。食欲素 -A和食欲素 -B集中在脊髓背角的浅层，并且在背根神经节细胞中发现了食欲素 -A和食欲素 -1受体。静脉注射食欲素 -A在角叉菜胶试验中产生抗热痛觉过敏作用，食欲素 -A的这种作用是由外周初级传入终末处食欲素 -1受体的激活介导的。鞘内和脑室内注射食欲素 -A在福尔马林试验、角叉菜胶试验和神经性疼痛模型中产生镇痛作用，食欲素 -A的这些作用被认为是由食欲素 -1受体的激活介导的。在0至3日龄大鼠的离体脊髓标本中，以C纤维强度单次电击刺激背根所诱导的缓慢去极化反应和时间总和现象，被食欲素 -A、食欲素 -B和选择性食欲素 -2受体激动剂[Ala11 D-Leu15]食欲素 -B有效减弱。这表明，在新生大鼠脊髓中，参与伤害性感受传递的是食欲素 -2受体，而非食欲素 -1受体。
