IMBECU   20882
INSTITUTO DE MEDICINA Y BIOLOGIA EXPERIMENTAL DE CUYO
Unidad Ejecutora - UE
artículos
Título:
PUBERTY AND NEUROSTEROIDS: EFFECT OF ALLOPREGNANOLONE ON GABA AND GLUTAMATE RELEASE AND DIFFERENTIAL HYPOTHALAMIC EXPRESSION AND ACTIVITY OF 3α-HOR IN FEMALE RATS
Autor/es:
GIULIANI FA; ESCUDERO C.; CASAS S.; BAZZOCCHINI V.; YUNES R.; LACONI, M.; CABRERA R.
Revista:
NEUROSCIENCE
Editorial:
PERGAMON-ELSEVIER SCIENCE LTD
Referencias:
Lugar: Amsterdam; Año: 2013 p. 64 - 75
ISSN:
0306-4522
Resumen:
The hypothalamic release of glutamate and
GABA regulates neurosecretory functions that may control
the onset of puberty. This release may be influenced by neurosteroids
such as allopregnanolone. Using superfusion
experiments we examined the role of allopregnanolone on
the K+-evoked and basal [3H]-glutamate and [3H]-GABA
release from mediobasal hypothalamus and anterior preoptic
area in prepubertal, vaginal opening and pubertal (P) rats
and evaluated its modulatory effect on GABAA and NMDA
(N-methyl-D-aspartic acid) receptors. Also, we examined
the hypothalamic activity and mRNA expression of 3ahydroxysteroid
oxidoreductase (3a-HSOR) enzyme that
synthesizes allopregnanolone using a spectrophotometric
method and RT-PCR, respectively. Allopregnanolone
increased both the K+-evoked [3H]-glutamate and [3H]-
GABA release in P rats, being the former effect mediated
by the modulation of NMDA receptors as was reverted by
Mg2+ and by the NMDA receptor antagonist AP-7 and the latter
by the modulation of NMDA and GABAA receptors as
was reverted by Mg2+ and the GABAA receptor antagonist
bicuculline. The neurosteroid also increased the basal
release of [3H]-glutamate in VO rats in an effect that was
dependent on the modulation of NMDA receptors as was
reverted by Mg2+. On the other hand we show that allopregnanolone
reduced the basal release of [3H]-GABA in P rats
although we cannot elucidate the precise mechanism bywhich the neurosteroid exerted this latter effect. The enzymatic
activity and the mRNA expression of 3a-HSOR were
both increased in P rats regarding the other two studied
stages of sexual development. These results suggest an
important physiological function of allopregnanolone in
the hypothalamus of the P rat where it might be involved
in the fine tuning of neurosecretory functions related to
the biology of reproduction of the female rats.