Johnston A R, Murnion B, McQueen D S, Dutia M B
Department of Physiology, Medical School, Edinburgh, UK.
Exp Brain Res. 1993;93(2):293-8. doi: 10.1007/BF00228397.
The effects of 5-hydroxytryptamine (5-HT) and related compounds on the discharge rate of tonically active medial vestibular nucleus (MVN) neurones were studied in an in vitro slice preparation of the dorsal brainstem of the rat. The majority (87 of 107, 82%) of MVN neurones were excited by 5-HT. Nine cells (8%) showed a biphasic response to 5-HT, which consisted of a brief inhibition followed by excitation. Eleven cells (10%) were inhibited by 5-HT. The excitatory effects of 5-HT were mimicked by alpha-methyl-5-HT and antagonised by ketanserin and ritanserin, indicating the involvement of the 5-HT2 subtype of 5-HT receptor. In biphasic cells, blockade of 5-HT2 receptors by ketanserin reduced the excitatory component of the response and revealed an enhanced initial inhibition. The inhibitory effects in biphasic cells, and in cells that showed a pure inhibition in response to 5-HT, were blocked by pindobind-5-HT and mimicked by 8-hydroxy-2-(di-n-propylamino)-tetralin indicating the involvement of 5-HT1A receptors. The significance of these findings in relation to the effects of 5-HT on vestibular reflex function is discussed.
在大鼠背侧脑干的体外脑片制备中，研究了5-羟色胺（5-HT）及相关化合物对紧张性活动的内侧前庭核（MVN）神经元放电率的影响。大多数MVN神经元（107个中的87个，82%）受到5-HT的兴奋作用。9个细胞（8%）对5-HT表现出双相反应，即先有短暂抑制，随后兴奋。11个细胞（10%）受到5-HT的抑制。α-甲基-5-HT模拟了5-HT的兴奋作用，而酮色林和利坦色林则拮抗了这种作用，表明5-HT受体的5-HT2亚型参与其中。在双相反应的细胞中，酮色林阻断5-HT2受体可降低反应的兴奋成分，并显示出初始抑制增强。双相反应细胞以及对5-HT表现出单纯抑制作用的细胞中的抑制作用，被哌多班-5-HT阻断，并被8-羟基-2-（二正丙基氨基）-四氢萘模拟，表明5-HT1A受体参与其中。讨论了这些发现与5-HT对前庭反射功能影响的相关性。
