Large somal size is associated with the expression of galanin but not with neuronal birthdate in the sexually dimorphic male nucleus of ferret's preoptic area/anterior hypothalamus

Joong Jean Park, Jayen H. Patel, Luqman K. Dad, Stuart A. Tobet, Michael J. Baum

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Using Nissl and Golgi stains, a sexually dimorphic male nucleus (MN) comprised of a cluster of large cells with large dendritic arbors has been identified in the dorsal preoptic area/anterior hypothalamus (POA/AH) of male ferrets. The MN-POA/AH is formed only in males by the action of estradiol derived from the neural aromatization of testosterone during the last quarter of a 41-day gestation. The ferret's dorsal POA/AH is also characterized by a sex difference in the expression of the neuropeptide galanin which first arises in males around embryonic day (e) 34. We asked whether the male-typical phenotype of large somal size is related to birthdate and/or the capacity of dorsal POA/AH neurons to express galanin. In experiment 1 we labeled cohorts of cells born on E20, E24, or E28 by injecting the amniotic sacs of individual fetuses with the thymidine analogue bromodeoxyuridine (BrdU). On postnatal day 20, BrdU-immunoreactive cells were visualized immunohistochemically, counterstained with cresyl violet, and their somal sizes were measured. BrdU-immunoreactive cells were significantly larger in the males' MN-POA/AH than in a comparable region of females, regardless of when they were born between E20 and E28. In experiment 2 galanin-immunoreactive cells in the dorsal POA/AH of adult ferrets were visualized immunohistochemically, and their somal sizes were measured. Somal areas of galanin-immunoreactive cells were significantly larger in the MN-POA/AH of intact, breeding, or castrated and testosterone-treated males than in the corresponding area of females. Our results suggest that cells in the males' MN-POA/AH are more likely to be larger than cells in females' corresponding region, regardless of birthdate. Finally, in adulthood the male-typical phenotype of large Nissl-stained somal areas of MN-POA/AH cells may, in part, reflect their increased galanin expression.

Original languageEnglish
Pages (from-to)235-243
Number of pages9
JournalNeuroendocrinology
Volume68
Issue number4
DOIs
Publication statusPublished - 1998

Keywords

  • Anterior hypothalamus
  • Ferret
  • Galanin
  • Preoptic area
  • Somal area

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology
  • Endocrine and Autonomic Systems
  • Cellular and Molecular Neuroscience

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