Relationship of free and bound testosterone to sexual behavior in old rhesus males

Kathleen C. Chambers, David L. Hess, Charles H. Phoenix

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


Total serum testosterone concentrations, percentage of total serum testosterone bound to testosterone-binding globulin (TeBG), and estimates of free testosterone concentrations were determined in old and young male rhesus macaques. Also the sexual performance of the old (20 years and older) males was studied. The two groups did not differ in either the mean level of total testosterone or the index of free testosterone but the old males had a significantly higher percentage of testosterone bound to TeBG than did the young (10 years old) ones. We found significant negative correlations between the percentage of testosterone binding and sexual behavior in the old males. The percentage of bound testosterone was negatively correlated with the rates of contacting females, mounting, and intromission, and with the percentages of tests during which intromission and ejaculation occurred. Neither the total serum testosterone level nor the index of free testosterone correlated with the level of sexual performance.

Original languageEnglish (US)
Pages (from-to)615-620
Number of pages6
JournalPhysiology and Behavior
Issue number4
StatePublished - Oct 1981
Externally publishedYes


  • Index of free testosterone
  • Old rhesus male
  • Rhesus macaques
  • Sexual behavior
  • Testosterone level
  • Testosterone-binding globulin

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Behavioral Neuroscience


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