Functional interaction between orexin and CB1 receptors in the periaqueductal gray matter on antinociceptive responses induced by stimulation of the lateral hypothalamus
作者单位：Department of Physiology Iran University of Medical Sciences Neuroscience Research Center School of Medicine Shahid Beheshti University of Medical Sciences
会议名称：《中国神经科学学会第十二届全国学术会议》
会议日期：2017年
学科分类：1006[医学-中西医结合] 1002[医学-临床医学] 10[医学] 100602[医学-中西医结合临床]
关 键 词：Pain Lateral hypothalamus Periaqueductal gray Orexin-2 receptor CB1 receptor Tail-flick test
摘 要：Orexin receptors are found at high density in the ventrolateral periaqueductal gray matter（vl PAG）. Chemical stimulation of the lateral hypothalamus（LH） with carbachol induces antinociception in the tail-flick test, a model of acute pain. In the current study, we tried to examine the effect of TCS OX2 29 as an Ox2 r antagonist（5, 15, 50, 150 and 500 n M） microinjected into the vl PAG on LH-induced antinociception by carbachol administration（125 n M）. TCS OX2 29 dose dependently reduced carbacholinduced antinociception. In our previous study, we showed that the vl PAG CB1 receptors are involved in mediation of antinociceptive effect of carbachol. In the second set of experiments, animals were treated with carbachol 5 min after intra-vl PAG administration of 15 n M TCS OX2 29 and 1 n M AM251（as a selective CB1 receptor antagonist）, or 150 n M TCS OX2 29 and 10 n M AM251. The findings showed that the antinociceptive effect of orexin is partially mediated by activation of vl PAG Ox2 receptors. Furthermore, the administration of ineffective doses of Ox2 and CB1 receptor antagonists reduced the LHinduced antinociception. It seems that the orexinergic and cannabinoid systems in the PAG cooperate in the mediation of LH-induced antinociception.