Vn. Luine et al., GABAergic regulation of lordosis: Influence of gonadal hormones on turnover of GABA and interaction of GABA with 5-HT, NEUROENDOCR, 69(6), 1999, pp. 438-445
The role of GABAergic neurons in activating female sexual behavior and poss
ible mechanisms for GABAergic effects on behavior were examined in female r
ats. First, effects of the ovarian hormones estrogen and progesterone (P),
at doses which promote lordosis, on levels and turnover/activity of GABA, w
ere examined in brain areas which regulate lordosis. Utilizing AOAA, an inh
ibitor of GABA degradation, the accumulation rate of GABA (turnover/activit
y) was assessed in ovariectomized (Ovx), Ovx + estrogen and Ovx + estrogen
+ P-treated rats. Estradiol increased GABA accumulation rates in the arcuat
e-median eminence and in the area dorsal to and surrounding the VMN (VMN-S)
. P administration following estrogen priming enhanced GABA turnover in the
medial preoptic area (mPOA) and further increased turnover in the VMNS whi
le GABA turnover decreased in the dorsomedial nucleus. No effects of hormon
es were noted in the VMN itself or in the dorsal midbrain central gray. Rev
erse dialysis of the GABAA antagonist bicuculline into the basomedial hypot
halamus was associated with a time-dependent inhibition of lordosis and a 3
00% increase in 5-HT release in the basomedial hypothalamus as measured by
in vivo dialysis. These results provide additional evidence that GABAergic
neurons mediate the physiological regulation of female sexual behavior and
suggest that such mediation may involve an interaction with 5-HT containing
neurons.