[Zoosocial behavior and the endocrine function of the gonads of male mice after destruction of the endings of the noradrenergic neurons in the brain].

Plasma testosterone levels and dominant behaviour were studied in groups of 6 male mice of different genotypes after selective destruction of noradrenergic nerve terminals. 6-hydroxydopamine was administered intraventricularly along with intraperitoneal injections of imipramine and nomifensine. Within a week, this was followed by obvious decrease of noradrenaline content in different regions of the brain in both dominant and subdominant animals, whereas the brain serotonin and dopamine levels did not change. A distinct decrease of NA concentration in the brain produced an increase of intermale aggression and elevation of plasma testosterone level in dominant mice, whereas brain NA alteration did not change testosterone level in the blood and decreased aggressiveness in subdominant animals. The difference seems to be due to functional activity of the brain noradrenergic system in dominant and subdominant mice.