Phaclofen-insensitive presynaptic inhibitory action of (+/-)-baclofen in neonatal rat motoneurones in vitro.
Phaclofen-insensitive presynaptic inhibitory action of (+/-)-baclofen in neonatal rat motoneurones in vitro.
复制标题
(l-)-巴氯芬对新生大鼠运动神经元的法氯芬不敏感突触前抑制作用体外。
DOI：
10.1111/j.1476-5381.1990.tb14718.x
复制
发表时间：
1990
影响因子：
7.3
通讯作者：
Dun,NJ
中科院分区：
文献类型：
--
作者：
Wang,MY;Dun,NJ
1. Intracellular recordings were made from antidromically identified motoneurones in transverse spinal cord slices from neonatal (12-16 day) rats. 2. Superfusion of (+/-)-baclofen (0.5-50 microM) reduced the excitatory postsynaptic potentials (e.p.s.ps) and inhibitory postsynaptic potentials (i.p.s.ps) evoked by dorsal root or dorsal root entry zone stimulation in a concentration-dependent manner; the calculated EC50 was 2.4 microM. Baclofen in comparable concentrations also reversibly eliminated spontaneously occurring e.p.s.ps and i.p.s.ps. 3. (-)-Baclofen was more effective as compared to baclofen in reducing the synaptic responses, whereas (+)-baclofen at concentrations as high as 50 microM was ineffective. 4. Baclofen (less than 5 microM) attenuated the synaptic responses without causing a significant change of passive membrane properties and depolarizations induced by exogenously applied glutamate. In addition to synaptic depression, baclofen (greater than 5 microM) caused a hyperpolarization associated with decreased membrane resistance in some of the motoneurones; the glutamate responses were also attenuated. 5. Baclofen reversibly depressed the spike after-hyperpolarization of the motoneurones. 6. GABA (1-10 mM) depressed synaptic transmission and depolarized or hyperpolarized motoneurones. While potentiated by the uptake inhibitor nipecotic acid, the synaptic depressant effect of GABA was not antagonized by bicuculline. 7. The synaptic depressant effect of baclofen was neither blocked by GABAA antagonists bicuculline and picrotoxin (10-50 microM) nor by the GABAB antagonist phaclofen (0.1-1 mM).(ABSTRACT TRUNCATED AT 250 WORDS)
