Sexual partner preference, hypothalamic morphology and aromatase in rams.

TitleSexual partner preference, hypothalamic morphology and aromatase in rams.
Publication TypeJournal Article
Year of Publication2004
AuthorsRoselli, CE, Larkin, K, Schrunk, JM, Stormshak, F
JournalPhysiol Behav
Date Published2004 Nov 15
KeywordsAnimals, Aromatase, Choice Behavior, Female, Hypothalamus, Male, Sex Characteristics, Sex Factors, Sexual Behavior, Animal, Sheep, Social Behavior

The male-oriented ram is a unique and valuable animal model for the study of hormonal, developmental and genetic contributions to sexual partner preference. Unlike most other mammalian models that are in use currently, variations in sexual attraction occur spontaneously in domestic ram populations. It is estimated that as many as 8-10% of rams exhibit a sexual partner preference for other males, classifying them as male-oriented rams. Studies have failed to identify any compelling social factors that can predict or explain the variations in sexual partner preferences of rams. Nor is there consensus on the endocrine and sensory responsiveness of male-oriented rams to other rams. However, a number of studies have reported differences in brain structure and function between male-oriented and female-oriented rams, suggesting that sexual partner preferences are neurologically hard-wired. Recently, we identified a sexually dimorphic nucleus (oSDN) in the sheep preoptic area-anterior hypothalamus. The oSDN is larger in female-oriented rams than in male-oriented rams and similar in size in male-oriented rams and ewes. In addition, mRNA levels for aromatase in the oSDN were higher in males than in females and were higher in female-oriented rams than in male-oriented rams. These results suggest a relationship between steroid hormones, specifically estrogens and oSDN morphology. In this review, we provide an overview of sexual behavior in rams and discuss the multiple factors that may contribute to the development and adult expression of same-sex partner preferences in rams.

Alternate JournalPhysiol. Behav.
PubMed ID15488542
Grant ListR01 RR14270 / RR / NCRR NIH HHS / United States