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7438161 
Journal Article 
Neuroendocrinology of Male Reproductive Behavior 
Baum, MJ; , 
2007 
Yes 
Hormones and Behavior
ISSN: 0018-506X
EISSN: 1095-6867 
Springer US 
Boston, MA 
Handbook of Neurochemistry and Molecular Neurobiology 
1-35 
17482616 
WOS:000247535000011 
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. (c) 2007 Elsevier Inc. All rights reserved.