Lovick T A
Department of Physiology, Medical School, University of Birmingham, UK.
Brain Res. 1993 Mar 19;606(1):92-8. doi: 10.1016/0006-8993(93)91574-c.
In rats anaesthetised with urethane, iontophoretic application of 5-hydroxytryptamine (5-HT, 5-70 nA) produced changes in ongoing activity of 41/44 neurones in the periaqueductal grey matter (PAG). The majority (85%) of responsive cells were inhibited and 15% were excited. The inhibitions were mimicked in 5/7 cells by iontophoresis of the 5-HT1A agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT, 10-30 nA) whilst excitation was produced in 3/5 cells by iontophoresis of the 5-HT2 agonist alpha-methyl-5-HT (10-30 nA). Selective activation of neuronal perikarya in nucleus raphe obscurus (NRO) by microinjection of 50-100 nl D,L-homocysteic acid (DLH) inhibited ongoing activity of 25/31 neurones tested in the PAG for periods of 30-580 s, mean 183.5 s. The duration of the inhibition was potentiated by between 36 and 300% during iontophoresis of the 5-HT re-uptake blocker paroxetine (1-25 nA, 6/6 cells). The results indicate that there is an extensive inhibitory serotonergic input to the PAG which originates, at least in part, from NRO.
在用乌拉坦麻醉的大鼠中，离子导入5-羟色胺（5-HT，5-70 nA）可使中脑导水管周围灰质（PAG）中44个神经元中的41个神经元的自发放电活动发生改变。大多数反应性细胞（85%）受到抑制，15%被兴奋。5-HT1A激动剂8-羟基-2-（二正丙基氨基）四氢萘（8-OH-DPAT，10-30 nA）离子导入可模拟5/7个细胞中的抑制作用，而5-HT2激动剂α-甲基-5-HT（10-30 nA）离子导入可使3/5个细胞产生兴奋。通过微量注射50-100 nl D，L-高半胱氨酸（DLH）选择性激活中缝隐核（NRO）中的神经元胞体，可抑制PAG中31个被测试神经元中的25个神经元的自发放电活动30-580秒，平均183.5秒。在离子导入5-HT再摄取阻滞剂帕罗西汀（1-25 nA，6/6个细胞）期间，抑制持续时间增强了36%至300%。结果表明，PAG存在广泛的抑制性血清素能输入，至少部分起源于NRO。
