Corticosterone and carbenoxolone effects on neural cell proliferation in the adult songbird

Acute and/or chronic stress can negatively affect neurogenesis of mammals and birds via action of the stress hormone and glucocorticoid, corticosterone (CORT). The zebra finch ventricular zone (VZ) has persistent neurogenesis during adulthood. Our lab previously reported that the adult female VZ is protected from stress-induced declines in neurogenesis in contrast to males. 11-beta hydroxysteroid dehydrogenases (11β HSDs) regulate CORT, with the type 2 isoform de-activating it. In this study, we tested the hypothesis that inhibiting this enzyme with carbenoxolone will reduce neurogenesis in females and further decrease it males. We measured cell proliferation using the mitotic marker 5’-bromo-2’deoxyuridine (BrdU) and treated brain slices with CORT reflecting increasing stress levels with or without carbenoxolone. We found no effect of CORT or CORT paired with CBX on either male or female neurogenesis. Our findings indicate that perhaps 11β HSD2 does not mediate the previously-observed sex differences in adult neurogenesis