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目的:研究下丘脑前核微量注射褪黑素及其受体拮抗剂对正常血压和应激性高血压大鼠心血管活动的影响。方法:微量注射褪黑素及其受体拮抗剂至下丘脑前区前核,记录血压、平均动脉压和心率。结果:微量注射褪黑素可降低平均动脉压,其竞争性ML_1受体拮抗剂luzindole可完全阻断褪黑素的降压反应,而其ML_2受体拮抗剂prazosin不能阻断褪黑素的降压反应。结论:褪黑素为一种降压因子,其降压反应主要通过激活ML_1受体,而不是ML_2受体来介导的,下丘脑前核是褪黑素影响心血管活动的重要中枢部位。
Objective: To study the effects of melatonin and its receptor antagonists injected into the hypothalamic anterior nucleus on cardiovascular activities in normotensive and stress-induced hypertensive rats. Methods: Melatonin and its receptor antagonist were injected into the anterior hypothalamic nucleus to record the blood pressure, mean arterial pressure and heart rate. Results: Microinjection of melatonin reduced mean arterial pressure, and its competitive ML 1 receptor antagonist luzindole completely blocked the antihypertensive response of melatonin, while prazosin, an ML 2 receptor antagonist, did not block the decrease of melatonin Pressure reaction. CONCLUSION: Melatonin is a kind of antihypertensive factor. Its antihypertensive response is mainly mediated by activation of ML_1 receptor, but not ML_2 receptor. The hypothalamic nucleus is an important central site of melatonin affecting cardiovascular activity.