Lack of activational influence of ovarian hormones on the size of the female rat's corpus callosum

Christine M. Mack, Roslyn H. Fitch, Lynn A. Hyde, Amy Jo Seaman, Heather A. Bimonte, Wei Wei, Victor H. Denenberg

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

The sex difference in the midsagittal area of the adult rat corpus callosum (CC) has been shown to be mediated in part, by gonadal steroids in early development, with the sensitive period of hormone action in the female extending at least up to postnatal day 25. Given this prolonged sensitivity, the current study attempted to delineate organizational vs. activational influences of gonadal hormones on the female rat CC. In Experiment 1, callosal size was examined across the estrous cycle at 52 and 0 days of age. In Experiment 2, females were ovariectomized at 78 days and CC parameters assessed at 110 days. Last, in Experiment 3, females were ovariectomized at 78 days and sacrificed at 110 days. Last, in Experiment 3, females were ovariectomized at 78 days and sacrificed at 110 days; in addition, sham females were sacrificed during proestrus or estrus. Neither stage of estrous cycle nor adult ovariectomy affected midsagittal CC size. These results provide evidence for organizational effects of ovarian steroids on the female callosum, with the sensitive period of hormone action ending sometime between days 25 and 78.

Original languageEnglish (US)
Pages (from-to)431-434
Number of pages4
JournalPhysiology and Behavior
Volume60
Issue number2
DOIs
StatePublished - Aug 1996
Externally publishedYes

Keywords

  • Activational influence
  • Corpus callosum
  • Female rat
  • Ovarian hormones

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Behavioral Neuroscience

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