孤束核微注射5-羟色胺系统药物对大鼠睡眠-觉醒的影响及机制

Effects and Mechanisms of Systemic 5-HT Microinjections in Nucleus of the Solitary on Sleep-Wakefulness Cycles in Rats

目的:探讨孤束核(NST)微注射5-羟色胺(5-HT)系统药物对大鼠睡眠-觉醒的影响及其机制。方法:选用雄性SD大鼠,分7组,孤束核分别微注射5-羟基色氨酸(5-HTP)、非特异性5-HT受体阻断剂麦角新碱(MS)、5-羟色胺1A受体(5-HT1AR)激动剂8-OH-DPAT、5-HT1AR拮抗剂spiperone、cAMP、cAMP依赖的蛋白激酶A(PKA)拮抗剂H89和生理盐水(NS)后,采用光电脑电机记录脑电和肌电;采用免疫组化ABC法检测NST处5-HT1AR及5-HT表达情况。结果:与处理前相比,NS组和MS组大鼠睡眠-觉醒各期差异均无统计学意义,5-HTP组、8-OH-DPAT组和H89组给药后均显示觉醒期(W)缩短,异相睡眠(PS)延长(P<0.05或P<0.01),8-OH-DPAT组和H89组慢波睡眠(SWS)延长(P<0.01或P<0.05);spiperone组和cAMP组W延长(P<0.01或P<0.05),SWS缩短(P<0.01或P<0.05),spiperone组PS缩短(P<0.05)。免疫组化结果显示,与NS组相比,5-HTP组的5-HT1AR阳性细胞数较多,5-HT能神经纤维末梢5-HT表达增强,MS组则结果相反。结论:作为睡眠诱发区,孤束核很可能是通过5-羟色胺作用于5-HT1AR,使cAMP生成减少,PKA磷酸化减少而发挥使觉醒减少、睡眠增加的生物学效应。

Objective： To Study the effects and mechanisms of systemic 5-HT administration on sleep-wakefulness cycle by mieroinjeetion into nucleus of solitarius tracts （NST） in rats. Methods： Male SD rats were divided into seven groups and were given 5-hydroxytryptophan （5-HTP）, 5-HTR antagonist methysergide （MS）, 5-HT1AR agonist 8-OH-DPAT, 5-HT1AR antagonist spiperone, cAMP, PKA antagonist H89 and normal saline （NS） separately by microinjection into the nucleus of solitarius tract. The electroencephalogram（EEG） and electromyogram （EMG） were recorded by a NIHON KOHOEN polygragh instrument. The ABC immunohistochemieal method was used to detect 5-HT1AR positive neurons and 5-HT expression in NST of rats. Results： Compare with pre-administration, there were no significant change in sleep-wakefulness cycle after administration in NS group and MS group. There were a significant decline of waking period and an increase of paradoxical sleep（PS） in 5-HTP group, 8-OH-DPAT group and H89 group （P 〈 0.05 or P 〈 0.01）. There were also a significant increase of the slow wave Sleep（SWS） in 8-OH-DPAT group and H89 group （P 〈 0.01 or P 〈 0.05）. There were significant increase of the waking period （P〈 0.01 orP〈 0.05） and decline of SWS （P〈 0.01 orP〈 0.05） in the spiperone group and cAMP group, and significant decline of PS in spiperone group （P 〈 0.05）. The immunohistochemieal results showed that, compared with the NS group, there were more 5-HT1AR positive neurons and more 5-HT expression in serotonergie nerve terminals in 5-HTP group. The reverse results came from MS group. Conclusion： As an inducing area, the important role of NST in the sleep-wakefulness cycle to shorten the waking phase and prolong the sleep phase maybe mediated by the function of 5-HT which binds to 5-HT1AR and decreases the cAMP formation and phosphorylated PKA.