对氯苯丙胺酸调制脊髓薄片运动神经元的活动

MODULATION OF MOTONEURON ACTIVITIES BY p-CHLOROPHENYLALANINE IN SPINAL CORD SLICES

在新生大鼠脊髓薄片进行运动神经元(MN)细胞内记录,观察5-羟色胺(5-HT)10～100μmol/L或对氯苯丙胺酸(PCPA)5～10#mol/L的作用,发现灌流5-HT(n=10)或PCPA(n=5)以可比的方式抑制背根刺激诱导的兴奋性突触后电位,但增大外源性芥氨酸反应(n=3),在两个MN还诱发伴膜电阻降低的超极化反应。PCPA的作用与5-HT相比呈发生缓慢、持续长久的特点。结果提示PCPA可能通过激活下行5-HT能纤维而模拟5-HT对MN活动的调制作用。

Intraccllular recordings were made from motoncurons(MNs) in the spinal cord slices of nconatc rats(7-16 days). It was found that excitatory postsynaptic potentials ( EPSPs) evoked by dorsal root stimulation were depressed by supcrfusion of scrotonin(5-HT) 10-100μmol/ L(n= 10), and in a comparable manner by p-chlorophcnylalaninc(PCPA) 5- 10 μmol/L(n = 5). Both of 5-HT and PCPA increased exogenous glutamatc-induced depolarization even without remarkable changes in membrane potential and input rcsistancc(n = 3). In other 2 MNs, 5-HT and PCPA induced a hypcrpolarization with decrease of membrane resistance and almost nullified EPSPs. As compared with 5-HT , PCPA exhibited characteristics of slow-developing and long-lasting action. The results suggest that PCPA mimics the 5-HT actions on MNs possibly by its stimulating action on the dcccnding 5-HT fibers.