【作者】 王金志；

【导师】 俞光第； 蒋星红；

【作者基本信息】 苏州大学 ， 生理学， 2001， 硕士

【摘要】 本文采用在体细胞外记录大鼠下丘脑视交叉上核（SCN）神经元单位放电的方法，在昼夜周期的不同时相（主观白天的CT10-14和主观黑夜的CT22-02），采用松果腺摘除（PINX）和采用氨甲蝶呤（MTX）抑制褪黑素（MEL）合成的方法分别去除内源性MEL的主要来源后，观察大鼠SCN神经元自发放电的变化以及外源性MEL的作用。 实验结果表明：（1）不管是主观白天还是主观黑夜，SCN神经元存在规则放电、不规则放电和簇状放电三种型式的自发放电，摘除松果腺和抑制MEL合成，对这三种放电型式未见明显影响；（2）SCN神经元的自发放电频率在主观白天高，在主观黑夜低。摘除松果腺和抑制MEL合成后，放电频率昼高夜低的节律性消失，放电频率有所提高；（3）SCN神经元对外源性MEL起抑制反应，ML-1受体拮抗剂luzindole能阻断这种抑制效应，而ML-2受体拮抗剂哌唑嗪（prazosin）则不能，提示MEL的抑制作用是由ML-1受体介导的。 实验结果提示：松果腺作为大鼠昼夜节律组构中的一个调整器，分泌MEL并由ML-1受体介导，对SCN神经元有抑制性的调节作用。更多还原

【Abstract】 The spontaneous firing of hypothalamic suprachiasmatic nucleus (SCN) neurons was recorded in vivo extracellularly during the subjective day (CT1O-14) and the subjective night (CT22-02) after pinealectomy (PINX) and after inhibition of endogenous melatonin (MEL) synthesis by methotrexate (MTX), and the effect of exogenous MEL on the neuronal firing of SCN was examined. The results were as follows: (1) In the spontaneous firing of SCN neurons there exist three types of discharge (regular firing, irregular firing and burst firing), which persist during both the subjective day and the subjective night, as well as after PINX and after inhibition of endogenous MEL synthesis. (2) The firing rate of SCN neurons was high during the subjective day and low during the subjective night, this circadian rhythm disappeared and the firing rate was increased after PINX and after inhibition of endogenous MEL synthesis. (3) The effect of exogenous MEL on SCN neurons was inhibitory in nature, which was blocked by ML-l receptor antagonist luzindole, but not by ML-2 receptor antagonist prazosln. The results suggested that the pineal gland ,as a regulator in circadian rhythm organization, secretes MEL, which, in turn,elicits an inhibitory regulatory effect on SCN neurons through ML-l receptor.更多还原