Intracranial administration of corticotropin-like peptides increases incidence of amphibian reproductive behavior.

Male rough-skinned newts (Taricha granulosa) exhibit an increase in sexual behavior (amplectic clasping) following intracerebroventricular (ICV) injection of adrenocorticotropin (ACTH 1-39), ACTH 4-10, or melanocyte-stimulating hormone (alpha MSH). In contrast, intraperitoneal (IP) administration of ACTH 1-39 or corticosterone significantly decreases the incidence of sexual behavior in male newts. These results suggest that a corticotropin-like peptide acts centrally to enhance sexual behavior and that systemic ACTH acts on the interrenal tissue to inhibit sexual behavior by stimulating the release of corticosterone.