The ram as a model for behavioral neuroendocrinology

Anne Perkins, Charles E. Roselli

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


The sheep offers a unique model to study male sexual behavior and sexual partner preference. Rams are seasonal breeders and show the greatest libido during short days coincident with the resumption of ovarian cyclicity in the ewe. Threshold concentrations of testosterone are required for the acquisition and display of adult sexual behavior. In addition, estrogens produced from circulating testosterone by cytochrome P450 aromatase in the preoptic area are critical for the maintenance of sexual behaviors in rams. Sex differences in adult reproductive behaviors and hormone responsiveness are the result of permanent organizational effects exerted by testosterone and its metabolites on brain development. Early exposure to ewes enhances ram sexual performance, but cannot prevent some rams from exhibiting male-oriented sexual partner preferences. Neurochemical and neuroanatomical studies suggest that male-oriented ram behavior may be a consequence of individual variations in brain sexual differentiation.

Original languageEnglish (US)
Pages (from-to)70-77
Number of pages8
JournalHormones and Behavior
Issue number1
StatePublished - Jun 2007


  • Aromatase
  • Preoptic area
  • Rams
  • Sexual partner preference
  • Sexually dimorphic nucleus
  • Sheep

ASJC Scopus subject areas

  • Endocrinology
  • Endocrine and Autonomic Systems
  • Behavioral Neuroscience


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