Interrelationship between NO and androgenic activity in mice, Mus musculus, following temporal phase relation of serotonergic and dopaminergic neural oscillations.

TLDR: It is concluded that an inverse correlation exists between testicular steroidogenic activity and NO activity of laboratory mice under control and experimentally modulated gonadal conditions.

Abstract: The present study was designed to monitor the correlation of gonadal steroidogenic activity and nitric oxide (NO) of plasma and testis of male laboratory mouse, Mus musculus, under (1) control/basal and (2) experimental conditions. In the first study, male mice (n = 6) of three age groups (3-week-old sexually immature, 9-week-old sexually mature and 1.5-year-old) were assayed for plasma testosterone and level of NO in the plasma and testis. The immunoreactivity of 3-β-hydroxysteroid dehydrogenase (3-β-HSD) and androgen receptors (ARs) was also detected in testis and epididymis, respectively. In the second study, the reproductive state of mice was altered by injecting precursors of serotonin 5-hydroxytryptophan (5-HTP) and dopamine L-dihydroxyphenylalanine (L-DOPA) daily for 13 days. In one subgroup, mice received their daily injections 8 h apart and in another subgroup 12 h apart. A third subgroup of control mice received two daily injections of normal saline. After the completion of the experiment, the mentioned parameters were measured. The results showed a significant increase in levels of NO and a lowering of the immune reactivity of 3-β-HSD and AR, in both leydig cells and the epididymis in the sexually immature, old-age mice as well as in the mice that received 5-HTP and L-DOPA in the 8-h temporal relation, whereas opposite effects were observed in the sexually mature mice as well as in the mice that received 5-HTP and L-DOPA in the 12-h temporal relation. These findings led us to conclude that an inverse correlation exists between testicular steroidogenic activity and NO activity of laboratory mice under control and experimentally modulated gonadal conditions.