Rapid actions of the neurosteroid allopregnanolone on ovarian and hypothalamic steroidogenesis: Central and peripheral modulation

CACERES ANTONELLA RR; VEGA OROZCO, A.; LACONI M.; CABRERA, RJ.

JOURNAL OF NEUROENDOCRINOLOGY.

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2020 vol. 32 p. 1 - 13

0953-8194

AbstractThe present study aimed to determine whether an i.c.v. administration of allopregnanolone(ALLO) rapidly modifies the hypothalamic and ovarian 3β-hydroxysteroid dehydrogenase(3β-HSD) enzymatic activity and gene expression in in vivo and ex vivosystems in pro-oestrus (PE) and dioestrus I (DI) rats. Animals were injected with vehicle,ALLO, bicuculline or bicuculline plus ALLO and were then killed. In the in vivo experiment,the hypothalamus, ovaries and serum were extracted and analysed. In theex vivo experiment, the superior mesenteric ganglion - ovarian nerve plexus - ovarysystem was extracted and incubated during 120 minutes at 37 ºC. The serum andovarian compartment fluids were used to determine progesterone by radioimmunoanalysis.In the in vivo experiments, ALLO caused a decrease in hypothalamic andovarian 3β-HSD enzymatic activity during PE. During DI, ALLO increased hypothalamicand ovarian 3β-HSD activity and gene expression. The ovarian 3β-HSD activityincreased in both stages in the ex vivo system; gene expression increased only duringDI. ALLO induced an increase in serum progesterone only in D1 and in the ovarianincubation liquids in both stages. All findings were reversed by an injection of bicucullinebefore ALLO. Ovarian steroidogenic changes could be attributed to signalscoming from ganglion neurones, which are affected by the acute central neurosteroidstimulation. The i.c.v. administration of ALLO via the GABAergic system altered 3β-HSD activity and gene expression, modulating the neuroendocrine axis. The presentstudy reveals the action that ALLO exerts on the GABAA receptor in both the centraland peripheral nervous system and its relationship with hormonal variations. ALLOis involved in the ?fine tuning? of neurosecretory functions as a potent modulator ofreproductive processes in female rats.K E YWORDS3β-hydroxysteroid dehydrogenase, allopregnanolone, ovary, RGABAA, steroidogenesis