摘要
本实验采用多管玻璃微电极微电泳技术,观察褪黑激素(melatonin,MT)对海马神经元单位放电的影响,并探讨该激素对阿片受体和5-HT受体作用的关系.结果显示,MT对自发放电和谷氨酸诱发放电单位及经电生理学鉴定的锥体细胞具有明显的抑制作用。这种抑制效应呈现剂量依赖性,且不被Mg^(2+)阻断。海马神经元的自发放电频率呈现昼夜差异,但白天与黑夜给予MT对这些神经元电活动的影响无明显差异。同一个神经元对MT产生抑制反应,而对吗啡却呈现兴奋反应.纳洛酮拮抗吗啡的兴奋和抑制效应,但未能阻断MT的效应。赛庚啶拮抗5-HT和MT的抑制和兴奋效应。本文结果表明:(1)MT可直接改变海马神经元的电活动;(2)MT对海马神经元活动的抑制除了通过激活它本身的受体外,还可能部分地以5-HT受体为中介而发挥作用。
Effects of microiontophoretic application of melatonin on spontaneous and glutamate-evoked unit discharges and activity of electrophysiologically identified HPC were examined and the interactions of this hormone with opiate and 5-HT receptors were also investigated. The experiment was performed on adult male Sprague-Dawley rats weighing 220-310g under urethane and α-chloralose anesthesia and artificial ventilation. Majority of the neurons tested were located in the pyramidal layer of area CA1 as indicated by histological identification, Melatonin exhibited predominantly inhibitory effect on the three groups of neuronal activity in various hippocampal subfields. Very few neurons were excited by melatonin. The inhibitory effect of melatonin was dose-dependent and could not be blocked by magnesium ion. Spontaneous firing of hippocampal neurons displayed a circadian variation but there were no significant differences between the inhibitory effects induced by melatonin administration during the daytime and night-time. The same cells tested with morphine and melatonin exhibited an opsite pattern of response. The former drug produced predominant excitation, while the latter induced inhibitory effect. Naloxone antagonized both excitatory and inhibitory responses of most cells to morphine, but failed to block the effects elicited by melatonin. 5-HT and melatonin caused a similar pattern of inhibitory response in the same cells. Responses of majority of the neurons tested to 5-HT and melatonin were blocked by iontophoretic and intravenous application of cyproheptadine. There were no significant differences between the antagonistic effects of cyproheptadine against 5-HT and melatonin. The results show that (1) melatonin is capable of directly modifying the electrical activity of hippocampal neurons; (2) exogenous melatonin can be mediated partly by 5-HT receptors other than melatonin receptors.
出处
《中国应用生理学杂志》
CAS
CSCD
1989年第2期187-194,共8页
Chinese Journal of Applied Physiology
关键词
微电泳
褪黑激素
单位放电
海马
Melatonin
Cyproheptadine
Naloxone
Hippocampus
Microiontoph oresis
