5－羟色胺对大鼠下丘脑脑片弓状核神经元自发电活动的影响

在７４张大鼠下丘脑脑片上，用玻璃微电极记录到弓状核自发放电单位１７６个，其放电形式有三种：慢不规则型（１１９个，６７．６％）；快连续型（４６个，２６．１％）；位相型（１１个，６．３％）。５－ＨＴ（１０－６ｍｏｌ／Ｌ，３ｍｉｎ）对不同形式放电单位的作用均以抑制为主：对部分慢不规则单位（９／１１９）则表现为先抑制后兴奋的双相性反应，对少数神经元有兴奋作用。１２个被５－ＨＴ抑制的单位，其抑制作用不能被噻庚啶（ＣＨＤ，１０－５ｍｏｌ／Ｌ）阻断，４个被５－ＨＴ抑制的的单位中，其抑制作用可被二甲基麦角新碱（ＭＳＧ１０－６ｍｏｌ／Ｌ）部分或完全阻断。７个被５－ＨＴ抑制的单位，其中４个单位中，５－ＨＴ的抑制作用可被特异性５－ＨＴ１Ａ受体阻断剂Ｐｉｎｄｏｂｉｎｄ－５－ＨＴ１Ａ部分阻断；但另外３个单位的阻断效果不明显。上述结果表明：５－ＨＴ对弓状核不同形式放电单位的作用均以抑制为主，其作用可能是通过５－羟色胺（５－ＨＴ１）受体介导的，部分还可能是通过５－ＨＴ１Ａ受体介导的。

EFFECTS OF 5-HT ON ACTIVITY OF ARCUATE NEURONS OF RAT HYPOTHALAMIC SLICES

Extracellular recordings were made from 176 spontaneous discharging units in the arcuate nucleus of rat hypothalamic slices. Depending on the patterns of discharge, the units were divided into three types; slow irregular (76% ), fast continuous (26.5%) and phasic units (6.3%). The effect of 5-HT on the different types of units were observed. The results indicated that most of neurons were inhibited by 5-HT, and only a small portion of the cells showed excitation and a few of the slow irregular units showed "excitation after inhibition". With 5-HT 10-6 mol/L we found that 12 units inhibited by 5-HT could not be reversed by CHD, while the 4 inhibited units could be partly or completely reversed by MSG. 4 of the 7 neurons inhibited by 5-HT were partly blocked by Pindobind-5-HT1A but not for the remaining 3 neurons. The results suggest that the inhibitory effect of 5-HT on arcuate neurons may be mediated by 5-HT1 receptor, while some by 5-HT1A receptor.