IMBECU   20882
INSTITUTO DE MEDICINA Y BIOLOGIA EXPERIMENTAL DE CUYO
Unidad Ejecutora - UE
congresos y reuniones científicas
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, FERNANDO A; ESCUDERO, CARLA; CASAS, SEBASTIÁN; GARCÍA, SEBASTIÁN; BAZZOCCHINI VANESA; YUNES, ROBERTO; CABRERA RICARDO
Lugar:
VIÑA DEL MAR
Reunión:
Workshop; US-LATIN AMERICA WORKSHOP IN NEUROENDOCRINOLOGY; 2011
Institución organizadora:
INTERNATIONAL NEUROENDOCRINOLOGY FEDERATION
Resumen:
Introduction: The onset of puberty in female rats is normally triggered by an early pulsatile GnRH release and is evident when vaginal opening occurs. GnRH release appears to be regulated by transynaptic and glial inputs to the GnRH neuronal network, like glutamatergic and GABAergic inputs. Such neuronal activity may be regulated, in turns, by neurosteroids. Allopregnanolone (Allo) is one of the best characterized neurosteroids. It is synthesized by the enzyme 3α-hydroxysteroid oxydoreductase (3αHOR) from dihydroprogesterone. Previous works of our laboratory revealed that Allo stimulates GnRH release through NMDA receptors modulation in medial basal hypothalamus (MBH) and anterior preoptic area (APOA) of adult rats. However, little is known about allopregnanolone effects in an earlier stage such as puberty. Objetives: 1) To determine the gene expression of 3αHOR in MBH/APOAs of prepubertal rats (PP), rats on the day of vaginal opening (VO) and pubertal rats (P), 2) to measure the 3αHOR enzymatic activity in MBH/APOAs of PP, VO and P rats and 3) to determine the effect of Allo on GABA and glutamate release from MBH/APOA slices of PP, VO and P rats. Methods: 1) RNA was isolated from MBH/APOAs from PP (30d) (n=6), VO (39d) (n=5) and P (55d) (n=6) rats. Multiplex RT-PCR was made by using primers for 3αHOR and ciclophiline (housekeeping gene). Relative optic density was obtained after electrophoresis and etidium bromide dying. 2) MBH/APOAs of rats of the three experimental groups (n=8 for each group) were homogenized and ultracentrifuged. Then, citoplasmatic fraction was isolated to assay 3αHOR enzymatic activity by spectrophotometric measure of oxidation of NADPH after addition of dihydroprogesterone. 3) MBH/APOA slices of rats in the three experimental groups were assayed for K+ 28mM evoked [3H]-GABA and [3H]-Glutamate release. They were superfused with Krebs Ringer Bicarbonate Glucose (KRBG) buffer as vehicle or alloprengnanolone 120 nM. Results were compared by ANOVA1 and Turkey’s post test, and differences with p