青蛙松果体神经节细胞对吲■胺的电反应

ELECTRICAL RESPONSES OF THE GANGLION CELL IN FROG'S PINEAL BODY TO INDOLEAMINES

作者在明或暗适应青蛙(Rana esculenta)的松果体上,应用微量离子电泳施药方法,就5-甲氧基色胺(5-MT)、褪黑激素(MEL)与γ-氨基丁酸(GABA)对电生理上已鉴别的无色感神经节细胞自发放电的影响进行了对比研究。用5-MT检测了48个神经元,用MEL和GABA分别检测了50个神经元。GABA对其中80％的神经元有显著抑制作用,其余无反应。在用吲哚胺检测的神经元中,MEL只对36％的神经元有抑制作用,5-MT除对56％的神经元产生抑制作用外,还对6％的细胞活性有增强作用。根据5-MT和MEL在青蛙松果体内的作用特点看,吲哚胺化合物可能是一种神经调节物质,而不是神经递质。

A comparison study of the effects of microiontophoretically applied 5-methoxytryptamine (5-MT), melatonin (MEL) on electrophysiologically identified achromatic ganglion cells with that of GABA has been performed on both light- and dark-adapted pineal bodies of frog, Rana esculenta. Fourty-eight neuronal units for 5-MT and 50 neuronal units for both MEL and GABA have been tested in the present study. GABA caused a significant inhibition of the maintained activity in 80% of pineal neurons sampled, while 10 neurons (20%) were unresponsive. However, the indoleamines MEL and 5-MT depressed the maintained ganglion cell activity in 36%(MEL) and 56%(5-MT) of pineal neurons tested, and enhanced the activity in 6%(5-MT), the remaining cells being insensitive to the indole compounds. According to the action of 5-MT and MEL in frog pineal body these compounds should be considered as a modulator rather than as a neurotransmitter.