title: Steroidal and gonadal effects on neural cell proliferation in vitro in an adult songbird.
abstract: Neurogenesis in the adult songbird brain occurs along the ventricular zone (VZ), a specialized cell layer surrounding the lateral ventricles. To examine the acute effects of sex steroids on VZ cell proliferation, male and female adult zebra finch brain slices containing the VZ were exposed to 5-bromo-2'-deoxyuridine-5'-monophosphate (BrdU) in vitro. Slices from one hemisphere served as the control, while contralateral slices were treated with steroids, steroidogenic enzyme inhibitors or gonadal tissue itself. There were no significant effects on VZ cell proliferation in either sexes by acute exposure to 17beta-estradiol (E2), dihydrotestosterone (DHT), a cocktail of four sex steroids, and inhibitors of sex steroid synthesis (aminoglutethimide, ketoconazole, and fadrozole), or by activation of a mitochondrial cholesterol transporter. By contrast, dehydroepiandrosterone (DHEA) suppressed VZ cell proliferation in males, but not females, replicating previous observations involving treatments with corticosterone and RU-486. This suggests that DHEA suppresses proliferation in males via a glucocorticoid receptor-related mechanism. These results suggest that neurosteroidogenesis per se has little effect on acute VZ cell proliferation. Co-incubation with an ovary of female, but not male, slices significantly increased VZ cell proliferation; testicular tissue had no impact on proliferation in males or females. This suggests a role for a non-steroidal ovarian factor on adult female VZ cell proliferation. We also have evidence that previously reported sex-differences in BrdU-labeling along the adult VZ (males>females) result from a more rapid loss of cells in females. Sex differences in steroid action and cell death along the VZ may contribute to the maintenance of the sexually dimorphic song system.
authors.affiliation: Department of Integrative Biology and Physiology and Laboratory of Neuroendocrinology, Brain Research Institute, University of California, Los Angeles, California, 90095, USA. Electronic address: mirzatoni@ucla.edu.
authors.forename: Anahid
authors.initials: A
authors.lastname: Mirzatoni
authors.affiliation: Department of Integrative Biology and Physiology and Laboratory of Neuroendocrinology, Brain Research Institute, University of California, Los Angeles, California, 90095, USA.
authors.forename: Stephanie M
authors.initials: SM
authors.lastname: Dong
authors.affiliation: Department of Integrative Biology and Physiology and Laboratory of Neuroendocrinology, Brain Research Institute, University of California, Los Angeles, California, 90095, USA.
authors.forename: Marjorie
authors.initials: M
authors.lastname: Guerra
authors.affiliation: Department of Integrative Biology and Physiology and Laboratory of Neuroendocrinology, Brain Research Institute, University of California, Los Angeles, California, 90095, USA.
authors.forename: Yin
authors.initials: Y
authors.lastname: Zhen
authors.affiliation: Department of Integrative Biology and Physiology and Laboratory of Neuroendocrinology, Brain Research Institute, University of California, Los Angeles, California, 90095, USA.
authors.forename: Amnon
authors.initials: A
authors.lastname: Katz
authors.affiliation: Department of Integrative Biology and Physiology and Laboratory of Neuroendocrinology, Brain Research Institute, University of California, Los Angeles, California, 90095, USA.
authors.forename: Barney A
authors.initials: BA
authors.lastname: Schlinger
mesh_terms: D000367:Age Factors; D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D005260:Female; D046369:Finches / Q000502:physiology*; D012739:Gonadal Steroid Hormones / Q000494:pharmacology / Q000502:physiology*; D006066:Gonads / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D006727:Hormone Antagonists / Q000494:pharmacology; D008297:Male; D055495:Neurogenesis / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009924:Organ Culture Techniques; D020308:Songbirds
chemical_list: D012739:Gonadal Steroid Hormones; D006727:Hormone Antagonists