Gonadotropin inhibitory-hormone modulates neurosteroids-synthesizing enzymes expression and aggressive behavior in male sea bass, Dicentrarchus labrax

Neurosteroids are involved in the regulation of multiple behavioral and physiological processes metabolic activities vertebrate brain. However, central mechanisms how neurosteroid synthesis is regulated far to be understood. Gonadotropin-inhibitory hormone (GNIH) a hypothalamic neuropeptide that negatively regulates gonadotropin secretion but also inhibits sexual aggressive behaviors birds mammals by modulating aromatase enzyme neuroestrogen synthesis. In previous study performed male sea bass, we reported Gnih inhibited reproductive axis acting at three levels brain-pituitary-gonad axis. Moreover, presence cells fibers telencephalon, mesencephalon rhombencephalon suggests role regulating other important brain functions including behavior. this study, have analyzed effects intracerebroventricular (icv) injection sbGnih-2 on pituitary expression main neurosteroids-synthesizing enzymes ( stAR, cyp17, 3β-hsd, 17β-hsd, cyp19b, cyp7b) , as well estrogen androgen receptors erα, erβ1, erβ2, ar ). A combination immunohistochemistry situ hybridization was used identify putative interaction Gnih- aromatase-positive cells. We mirror test proxy measure aggression agonistic behavior after icv sbGnih-2. Central administration different doses reduced transcript 3β-hsd 17β-hsd increased cyp19b (brain aromatase) bass Neuroanatomical results suggest paracrine neuroendocrine actions could mediate expression. decreased erβ2 The analysis showed affected agonistic/aggressive revealed with mirror, lower time spent zone, latency establish contact higher mean distance zone. contrast, locomotor activity parameters measured were not injection. Taken together, our for first fish social-aggressive affects gene neurosteroid-synthesizing giving rise neuroandrogens neuroestrogens