γ-氨基丁酸在发育期大鼠视皮层长时程增强中的作用

目的　探讨γ 氨基丁酸 (GABA)在发育期大鼠视皮层诱导长时程增强 (LTP)中的作用。方法　应用视皮层脑片电生理技术 ,在大鼠视皮层脑片Ⅳ层刺激而在Ⅱ /Ⅲ层记录场电位 ,在第 2、3、5周龄的大鼠脑片中诱导LTP ,并比较发育过程中LTP的发生率以及GABA在诱导LTP中的作用。结果　在第 5周龄的大鼠脑片中诱导的LTP发生率明显低于第 2及第 3周龄的大鼠。GABAA受体拮抗剂Picrotoxin能够提高第 5周龄的大鼠LTP的发生率 ,但对于第 2及第 3周龄LTP无作用。结论　GABA对于视皮层发育关键期之前LTP的诱导并无易化作用 ;但对于发育关键期后的LTP有抑制作用

Effects of GABA on the induction of LTP in developing rat visual cortical slices

Objective To study the effects of gamma-aminobutyric acid (GABA) on the induction of long-term potentiation (LTP) in developing rat visual cortical slices. Methods Field potentials recorded from layer Ⅱ/Ⅲ induced by layer Ⅳ stimulation in rat visual cortical slices were examined. LTP was induced by tetanus in the slices on the postnatal 2, 3 and 5-week rats. The LTP incidences and the effects of GABA on them in different developmental stages were compared. Results LTP incidence at postnatal week 5 was significantly lower than that in other two groups. GABA A receptor antagonist picrotoxin could reverse this tendency, but had no effects on the LTP induction at the early postnatal age. Conclusion In visual cortex, GABA has inhibitory effects on the LTP induction only after the end of critical period and has no any facilitatory effects on the LTP induction before the developmental critical period.