Allopregnanolone and puberty: modulatory effect on glutamate and GABA release and

GIULIANI, FERNANDO; ESCUDERO, CARLA; CASAS, SEBASTIáN; YUNES, ROBERTO; LACONI, MYRIAM; CABRERA, RICARDO

NEUROSCIENCE

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2012

0306-4522

Abstract: The hypothalamic release of glutamate and GABA regulates neurosecretory functions that control the onset of puberty. This release may be influenced by neurosteroids such as allopregnanolone. We examined the role of allopregnanolone on K+-evoked [3H]-glutamate and [3H]- GABA release from mediobasal hypothalamus and anterior preoptic area in prepubescent, vaginal opening and pubescent rats and evaluated its modulatory effect on GABAA and NMDA receptors. Also, we examined the hypothalamic activity and mRNA expression of 3α-hydroxysteroid oxidoreductase - enzyme that synthesizes allopregnanolone - using a spectrophotometric method and RT-PCR respectively. Allopregnanolone increased [3H]-glutamate and [3H]-GABA release in pubescent rats, being the former effect carried out through modulation of NMDA receptors - as was reverted by Mg2+ - and the latter through modulation of NMDA and GABAA receptors - as was reverted by Mg2+ and the GABAA receptor antagonist bicuculline -. Enzymatic activity and mRNA expression of 3α- hydroxysteroid oxidoreductase were both increased in pubescent rats regarding the other groups. These results suggest an important physiological function of allopregnanolone in the hypothalamus of pubertal rat where might be involved in the ´fine tuning´ of neurosecretory functions related to the biology of reproduction of female rats.