侧脑室注射内吗啡肽-1对麻醉大鼠血压的影响

EFFECTS OF INTRACEREBROVENTRICULAR ADMINISTRATION OF ENDOMORPHIN-1 ON BLOOD PRESSURE IN ANESTHETIZED RATS

目的 观察侧脑室注射内吗啡肽 1(EM 1)对麻醉大鼠血压的影响 ,并初步探讨其作用机理。方法 侧脑室埋植导管给药 ,颈动脉插管测血压。结果 icvEM 1剂量依赖、纳洛酮敏感地降低麻醉大鼠的血压。icv或iv酚妥拉明、普萘洛尔和ivL NNA对EM 1引起的血压降低反应无影响 ;给予阿托品 (icv 2 5 μg·kg- 1 ;或iv 5 0 μg·kg- 1 )和切断双侧迷走神经减弱EM 1引起的血压降低反应。结论 icvEM 1可引起麻醉大鼠血压降低 ;此效应由阿片受体介导 ,有中枢M受体的参与 。

AIM To observe the effects of intracerebroventricular administration of endomorphin 1 on blood pressure in anesthetized rats and to assess its mechanism. METHODS Variations of mean arterial pressure (MAP) were observed after icv injection of endomorphine 1 in rats. The effects of iv or icv of various blockers, naloxone, phentolamine, propranolol, atropine and N ω nitro L arginine, on the variation of MAP caused by endomorphin 1 were observed. RESULTS Endomorphin 1 was shown to decrease MAP. The decrease in MAP was blocked by naloxone. Pretreatments with icv phentolamine and propranolol showed no effect on the vasodepression induced by icv endomorphin 1. However, pretreatment with icv atropine (25 μg·kg -1 ) attenuated the vasodepression. Pretreatments with iv phentolamine, propranolol and N ω nitro L arginine showed no effect on the vasodepression induced by icv endomorphin 1. But, pretreatment with iv atropine (50 μg·kg -1 ) and bilateral vagotomy attenuated the vasodepression. CONCLUSION Intracerebroventricular administration of endomorphin 1 produces vasodepressor response in anesthetized rats, which is mediated by opioid receptor. The vasodepression is associated with the central M cholinoceptor and the excitation of the vagus.