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为探讨视交叉上核 (SCN)神经元对褪黑素敏感性的昼夜节律改变的机制 ,先对仓鼠进行持续光照或摘除松果腺 ,然后制成下丘脑薄片 ,记录昼夜周期中 SCN神经元的自发单位放电 ,并观察其对褪黑素的反应。结果表明 ,取自正常光照动物的脑薄片 ,SCN对外源性褪黑素产生抑制反应的单位数量有昼多夜少的节律性。取自持续光照条件下或摘除松果腺动物的 SCN,对外源性褪黑素反应的昼夜节律性消失。持续光照条件下 ,起抑制反应的单位数量增加 ,引起反应的阈值无明显改变 ;在摘除松果腺后 ,起抑制反应的单位数量减少 ,引起反应的阈值升高。实验结果提示 ,SCN神经元对外源性褪黑素敏感性 ,与内源性褪黑素水平和褪黑素受体的适应性调制有关 ,还可能与松果腺和内源性褪黑素的其他神经生化作用有关。
To investigate the mechanism of melatonin sensitivity to circadian rhythm changes in suprachiasmatic nucleus (SCN) neurons, the hamsters were irradiated with light or excised pineal gland first, and then made into hypothalamic slices. The circadian rhythm of SCN neurons Spontaneous discharge unit, and observed its response to melatonin. The results showed that the number of SCN-inhibiting melatonin units produced by brain slices from normal animals was rhythmic for daytime and nighttime. Circadian rhythms of exogenous melatonin disappear when taken from SCNs under constant light or pineal exclusion. Under the condition of continuous light, the number of units that could inhibit the reaction increased, causing no significant change in the threshold of the reaction. After the removal of the pineal gland, the number of units that could inhibit the reaction decreased and the threshold of the reaction was raised. The experimental results suggest that the sensitivity of SCN neurons to exogenous melatonin is related to the regulation of endogenous melatonin levels and the adaptive modulation of melatonin receptors and may also be related to the effects of pineal gland and endogenous melatonin Other neurobiochemical effects.