Before the onset of pubey, the GnRH neurons are under the inhibitory control of GABA. Gamma amino butyric acid is a dominant inhibitory neurotransmitter in the hypothalamus. Inhibition of GnRH neurons by GABA is mediated Glutamergic neurons. A reciprocal innervations between GABAergic and Glutamergic neurons are found. During development GABA concentration and the number of GABAergic neurons increase from 13th day to second postnatal week, which is then followed by a decline in 3rd postnatal week. GABA release in the median eminence decrease concomitantly with the pubeal increase of GnRH secretion. Ref: Male Hypogonadism: Basic, Clinical, and Therapeutic Principles By Stephen J. Winters, Page 69 ; Goldfrank's Toxicologic Emergencies By Lewis R, Page 232 - 238.