ROLE OF GLUTAMIC-ACID DECARBOXYLASE IN THE PREPUBERTAL INHIBITION OF THE LUTEINIZING-HORMONE-RELEASING HORMONE-RELEASE IN FEMALE RHESUS-MONKEYS

To investigate further the role of GABA in the onset of puberty, this study examines whether glutamic acid decarboxylase (GAD), the catalyti c enzyme for GABA synthesis, is involved in the suppression of luteini zing hormone releasing hormone (LHRH) before puberty in rhesus monkeys . First, both GAD67 and GAD65 mRNAs were detectable by reverse transcr iption-PCR analysis in the preoptic area, medio-basal hypothalamus, po sterior hypothalamic area, and hippocampus of the monkey brain. Second , effects of antisense oligodeoxynucleotides (D-oligos) for GAD67 and GAD65 mRNAs on LHRH release were examined in conscious female rhesus m onkeys at the prepubertal stage using a push-pull perfusion method. Th e GAD67 or GAD65 antisense D-oligos or scrambled D-oligos were infused directly into the stalk-median eminence. Both the GAD67 and the GAD65 antisense D-oligos induced a large and prompt increase in LHRH releas e, whereas the scrambled D-oligos did not induce any significant effec t. The results suggest that the removal of GABA inhibition by interfer ing with GAD synthesis is effective in increasing LHRH release in prep ubertal monkeys. Third, the specificity of the antisense D-oligos on G AD levels was examined by incubating basal hypothalami with D-oligos i n vitro and subsequent Western blot analysis. The antisense D-oligos c onsistently decreased the proteins GAD67 and GAD65 compared with respe ctive control D-oligos. We conclude that the decrease of tonic GABAerg ic inhibition and maturational changes in GAD synthesis may be critica l factors for the onset of puberty in nonhuman primates.