CONICET | Buscador de Institutos y Recursos Humanos

Vega Orozco y Laconi: Both authors contribute equally. This work was aimed at determinining: 1) whether intracerebroventricular in vivo administration (i.c.v) of Allopregnanolone (Allo) modifies hypothalamic and ovarian 3?Ò-hydroxysteroid deshydrogenase (3?Ò-HSD) and 20-hydroxysteroid deshydrogenase (20?Ñ-HSD) enzymatic activities on proestrous (PE) and diestrous I (DI) days; 2) whether intracerebroventricular injection of Allo modifies, through the peripheral nervous system, the ovarian progesterone (P4) release and ovarian 3£]-HSD and 20?Ñ-HSD enzymatic activities and their gene expression in both stages. The protocol experimental was: vehicle (control), Allo and Allo plus Bicuculline- i.c.v injected rats. To assess the peripheral effect of Allo, the ex vivo superior mesenteric ganglion- ovarian nervous plexus-ovary system was isolated and after the P4 concentration was determined in the incubation buffer contained in the ovarian compartment at different incubation times. On PE, Allo diminished significantly hypothalamic and ovarian 3£]-HSD enzymatic activity and enhanced 20£-HSD activity. On DI, the hypothalamic activity of 3£]-HSD did not change while that of 20£-HSD decreased. The ovarian 3£]-HSD enzymatic activity increased while that of 20£-HSD decreased. In the ex vivo experiments, an increase in the ovarian P4 release at different times and the 3£]-HSD activity on PE and DI was observed. The activity of 20£-HSD decreased in both stages. No changes were observed in the gene expressions of the two enzymes on PE. However, on DI ovarian 3£]-HSD gene expression increased while that of 20£-HSD showed no changes. These effects were reverted with bicuculline injection. These results indicate that centrally administered Allo is able to modify hypothalamic and ovarian steroidogenesis in a time and cycle-depending way through the peripheral nervous system.