褪黑素对下丘脑氨基酸神经递质的影响

Effect of melatonin on hypothalamic amino acid neurotransmitters

应用纸电泳一双波长薄层扫描法测定了雄性小鼠下丘脑天冬氨酸（Ａｓｐ）．谷氨酸（Ｇｉｎ），及γ－氨基丁酸（ＧＡＢＡ）３种神经递质的含量和褪黑素（ＭＴ）对其影响。结果发现；下丘脑内３种氨基酸神经递质含量均呈明显的昼夜节律性变化，ＭＴ使Ａｓｐ、ＧＡＢＡ的昼夜节律曲线上移，在１２：００及２０：００ｈ升高Ａｓｐ、ＧＡＢＡ作用明显。不同剂量的ＭＴ腹腔注射能够升高Ａｓｐ．ＧＡＢＡ含量，以５μｇ·ｋｇ－１剂量为强，脑室注射ＭＴ的效果更佳。然而，不同浓度，不同时ＩＭＭＴ给药均不影响下丘脑Ｇｌｕ水平。利血平化小鼠的Ａｓｐ、ＧＡＢＡ含量升高，Ｇｌｎ含量则下降、给利血平化动物注射ＭＴ，则ＭＴ对Ａｓｐ，ＧＡ－ＢＡ的影响消失，而使Ｇｌｎ含量进一步下降。提示：ＭＴ对Ａｓｐ、ＧＡＢＡ昼夜节律产生影响，这种影响可能通过单胺神经递质介导。

The concentration of hypothalamic amino acid neurotransmitters (Asp, Gln and GABA) were determined by the paper electrophoretic dual wavelengh thin layer scanning method after melatonin (MT) administration in male mice. The results were as follows: three amino acid neurotransmitters all exhibited prominent circadian rhythm and MT could elevate the level of hypothalamic Asp and GABA, related to the time of the day. The maximal rising scope was at 12:00 and 20:00 h.It was also found that MT affect the concentration of Asp and GABA in relation to the doses administrated, the 5μg· kg-1 had the best response.Intraventricular administration of MT had stronger effect than ip. However,MT did not influence the concentration of Gln at different doses nor at different time.The concentration of Asp and GABA increased and Gln decreased after reserpine administration. After ip MT to the reserpinized mice, the effect of MT on Asp and GABA disappeared, while, the Glu concentration further decreased. It Is suggested that MT could effect the circadian rhythm of hypothalamic Asp, GABA amino acid neurotransmitters and these process might be mediated by monoamine neurotransmitters.