The effects of substance P and baclofen on motoneurones of isolated spinal cord of the newborn rat.
The effects of substance P and baclofen on motoneurones of isolated spinal cord of the newborn rat.
复制标题
P物质和巴氯芬对新生大鼠离体脊髓运动神经元的影响。
DOI：
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发表时间：
1980
影响因子：
2.8
通讯作者：
M. Yanagisawa
中科院分区：
文献类型：
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作者：
M. Otsuka;M. Yanagisawa
在新生大鼠离体脊髓中观察了P物质（SP）和巴氯芬的作用。从前根（L3-L5）细胞外记录运动神经元产生的电位变化。当SP（8 × 10 ~（-5）M）加入到水浴中时，运动神经元的去极化延迟1.1s。这种延迟的很大一部分可以解释为SP到达脊髓神经元作用部位所需的时间。当用含低Ca（0.1mM）和高Mg（1.6- 3.5mM）的人工脑脊液（CSF）灌注该制剂时，由背根刺激引起的并从相应的前根记录的脊髓反射被完全消除。在低钙介质中，SP（10（-7）M）对运动神经元的去极化作用增强，提示SP直接作用于运动神经元。10（-6）M巴氯芬抑制单突触反射约75%。巴氯芬在正常和0. 1 mM-Ca介质中均能显著抑制SP诱导的运动神经元去极化。在含0. 1 mM-Ca和1.6-2 mM-Mg的人工脑脊液中，比较了巴氯芬（10（-6）M）对各种去极化剂和SP反应的影响。巴氯芬使SP反应降低约80%，而对乙酰胆碱和甘氨酸的反应没有明显影响，对L-谷氨酸、GABA和去甲肾上腺素的反应降低10-22%。结果表明，巴氯芬通过拮抗作为递质释放的SP的作用来阻断某些初级传入突触的传递。
The effects of substance P (SP) and baclofen were studied in the isolated spinal cord of newborn rats. Potential changes generated in motoneurones were recorded extracellularly from the ventral root (L3-L5). When SP (8 X 10(-5) M) was introduced into the bath, the depolarization of motoneurones began with a delay of 1.1 s. A large part of this delay can be explained as a time needed for SP to reach the site of action on spinal neurones. When the preparation was perfused with artificial cerebrospinal fluid (CSF) containing low Ca (0.1 mM) and high Mg (1.6-3.5 mM), the spinal reflexes induced by dorsal root stimulation and recorded from the corresponding ventral root were completely abolished. The depolarizing action of SP (10(-7) M) on the motoneurones was potentiated in the low-Ca medium, suggesting that SP acts directly on the motoneurones. Baclofen at 10(-6) M depressed the monosynaptic reflex by about 75%. The SP-induced depolarization of motoneurones was greatly depressed by baclofen in both normal and 0.1 mM-Ca mediums. The effects of baclofen (10(-6) M) on the responses to various depolarizing agents were compared with that on the response to SP in artificial CSF containing 0.1 mM-Ca and 1.6-2 mM-Mg. The SP response was reduced by about 80%, whereas the responses to acetylcholine and glycine were not appreciably affected, and those to L-glutamate, GABA and noradrenaline were depressed by 10-22% by baclofen. The results suggest that baclofen blocks transmission at certain primary afferent synapses by antagonizing the action of SP that is released as a transmitter.