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大鼠上丘到外膝体P一物质投射的机能

蔡怀彬, 罗第荪

(中国科学院上海脑研究所，上海200031)

摘要

已知大鼠外膝体内有中脑上丘来的含P一物质的神经末梢，其机能不明。在离体的大鼠外膝体脑片上用单电极电压籍位的方法研究了P一物质对外膝体神经元电压依赖性离子通道的作用。结果表明，P一物质可以使静息膜去极化，并降低膜电导。这提示P一物质抑制了线性钾漏电流。此外，P一物质还抑制去极化激活的慢失活的钾电流、低阑值钙电流和超极化激活的内向整流(H或Q)电流。P一物质还可能抑制早钾((A)电流。因此，P一物质在外膝体视觉信号传递中的作用是使外膝体神经元从爆发反应方式或振荡状态转化为中继反应方式，易化突触传递，使视网膜的视觉信号忠实地传递到大脑皮层。

关键词： P一物质; 外膝体; 离子通道; 中脑上丘

FUNCTION OF SUBSTANCE-P PROJECTION FROM SUPERIOR COLLICULUS TO LATERAL GENICULATE NUCLEUS OF RATS

Cal HUAi_BIN , Luo (Lo) Fu-SUN

(Shanghai Brain Research Institute, Chinese Academy of Sciences, Shanghai 200031)

Abstract

Substance P immunoreactive terminals arising from the superior colliculus have been observed in the dorsal lateral geniculate nucleus of the rat. However，the functional role of this tachykininergic projection is still unknown. We studied the effects of substance P on voltage-dependent ion channels of lateral geniculate neurons in rat's in vitro brain slice with a single-electrode-voltage-clamp technique. It was found that substance
P caused a depolarizing shift of membrane potential with a decrease of membrane corn ductance，suggesting that substance P depressed the linear potassium leak current. In addition，substance P inhibited the slowly inactivated potassium current，low threshold (T-)calcium current and inward rectifier (H- or Q-) current. Probably，the transient potassium (A-) current was also depressed by substance P. Therefore，the effects of substance P were considered to transfer activities of lateral geniculate neurons from
burst response mode or oscillatory state to relay response mode，and to facilitate synaptic transmission，so that retinal visual signals could be relayed to the visual cortex with less distortion faithfully.

Key words: substance P;lateral genicualte nucleus; ion channels;superior colliculus of midbrain

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引用本文：

蔡怀彬, 罗第荪. 大鼠上丘到外膝体P一物质投射的机能[J]. 生理学报 1996; 48 (5): .

Cal HUAi_BIN , Luo (Lo) Fu-SUN. FUNCTION OF SUBSTANCE-P PROJECTION FROM SUPERIOR COLLICULUS TO LATERAL GENICULATE NUCLEUS OF RATS. Acta Physiol Sin 1996; 48 (5): (in Chinese with English abstract).