Orexins/hypocretins excite rat sympathetic preganglionic neurons in vivo and in vitro
Orexins/hypocretins excite rat sympathetic preganglionic neurons in vivo and in vitro
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DOI：
10.1152/ajpregu.2001.281.6.r1801
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发表时间：
2001-12-01
影响因子：
2.8
通讯作者：
Dun, NJ
中科院分区：
文献类型：
--
作者：
Antunes, VR;Brailoiu, GC;Dun, NJ
最近分离到的两个下丘脑多肽，即食欲素A和食欲素B，也被称为下丘脑降克素1和2，据报道在摄食和睡眠/觉醒过程中是重要的信号分子。下丘脑外侧含有食欲素的神经元投射到大鼠大脑和脊髓的许多区域，包括胸腰段脊髓的中间外侧细胞柱(IML)。在体内和体外的研究中，我们评估了食欲素作用于大鼠脊髓交感节前神经元(SPN)，增加交感神经流出的假说。首先，鞘内注射食欲素A(0.3、1和10nmol)使乌拉坦麻醉大鼠的平均动脉压(MAP)和心率(HR)分别增加5、18和30毫米汞柱以及10、42和85次/分钟。鞘内注射生理盐水效果不明显。鞘内注射增食欲素B可使MAP和HR平均增加11 mm Hg和40次/min。鞘内注射食欲素A抗体(1：500稀释度)可减弱食欲素A的升压作用，但不能被正常血清白蛋白减弱。静脉注射α(1)-肾上腺素能受体拮抗剂哌唑嗪(0.5 mg/kg)或β-肾上腺素能受体拮抗剂心得安(0.5 mg/kg)可显著降低增食欲素A引起的MAP和HR的升高。其次，从12至16天的大鼠脊髓切片上逆行鉴定SPN，进行全细胞贴片记录。灌流增食欲素A或增食欲素B(100或300 nM)可兴奋17个SPN中的12个，表现为膜去极化和/或神经元放电增加。在含TTX(0.5um)的Krebs溶液中，增食欲素A或B引起的去极化持续存在，表明该肽直接作用于SPN。我们在体内和体外的研究结果以及之前对IML中存在食欲素A免疫反应纤维的观察表明，当食欲素在IML中释放时，通过直接作用于SPN来增加交感神经流出。
The two recently isolated hypothalamic peptides orexin A and orexin B, also known as hypocretin 1 and 2, are reported to be important signaling molecules in feeding and sleep/wakefulness. Orexin-containing neurons in the lateral hypothalamus project to numerous areas of the rat brain and spinal cord including the intermediolateral cell column (IML) of the thoracolumbar spinal cord. An in vivo and in vitro study was undertaken to evaluate the hypothesis that orexins, acting on sympathetic preganglionic neurons (SPNs) in the rat spinal cord, increase sympathetic outflow. First, orexin A (0.3, 1, and 10 nmol) by intrathecal injection increased mean arterial pressure (MAP) and heart rate (HR) by an average of 5, 18, and 30 mmHg and 10, 42, and 85 beats/min in urethane-anesthetized rats. Intrathecal injection of saline had no significant effects. Orexin B (3 nmol) by intrathecal administration increased MAP and HR by an average of 11 mmHg and 40 beats/min. The pressor effects of orexin A were attenuated by prior intrathecal injection of orexin A antibodies (1:500 dilution) but not by normal serum albumin. Intravenous administration of the alpha (1)-adrenergic receptor antagonist prazosin (0.5 mg/ kg) or the beta -adrenergic receptor antagonist propranolol (0.5 mg/ kg) markedly diminished, respectively, the orexin A-induced increase of MAP and HR. Second, whole cell patch recordings were made from antidromically identified SPNs of spinal cord slices from 12- to 16-day-old rats. Superfusion of orexin A or orexin B (100 or 300 nM) excited 12 of 17 SPNs, as evidenced by a membrane depolarization and/or increase of neuronal discharges. Orexin A- or B-induced depolarizations persisted in TTX (0.5 muM)-containing Krebs solution, indicating that the peptide acted directly on SPNs. Results from our in vivo and in vitro studies together with the previous observation of the presence of orexin A-immunoreactive fibers in the IML suggest that orexins, when released within the IML, augment sympathetic outflow by acting directly on SPNs.