A STUDY OF THE REGULATORY ROLE OF GABA ON THE LHRH RELEASE IN THE MEDIAN EMINENCE OF RATS

The present study was undertaken to observe the effect of GABA and NAon LHRH neuronal terminals in the median eminence(ME).The results showedthat GABA(10~(-6)mol/L)significantly increased LHRH and NA release from ME,i.e,respectively from 27.3±2.5 pg/100 μl to 150.4±27.9 pg/100 μl and from50.9±4.2 pg/100 μl to 105.5±19.1 pg/100 μl(both P0.01 vs control group).These effects of GABA could be blocked by bicuculline.When bicuciline andGABA(10~(-6)mol/L)were added into the ME,the secretion of LHRH decreasedto 18.2±1.9 pg/100 μl and that of NA to 43.9±3.4 pg/100 μl.The effectof GABA on LHRH release may be mediated by NA.When endogenous NAwas depleted by reserpine,GABA increased LHRH secretion only by 26.5%instead of 451.9% as in the normal animal.