Gonadal hormones alter hypothalamic GABA and glutamate levels.

GABA and glutamate levels were measured in brain sites important for lordotic responding and in other hypothalamic sites after gonadal hormone treatments sufficient to activate lordosis. Estradiol increased GABA and glutamate in the ventromedial nucleus and the vertical diagonal bands. Progesterone administration to estradiol primed females led to a rapid decline of the transmitters in these areas. Results are discussed in relation to neuroendocrine regulation.