Effect of oxytocin on plasma testosterone levels in the male macaques ( [formula omitted])

The effect of oxytocin on testicular function was examined in the adult male long-tailed macaques ( Macaca fascicularis ). The monkeys were either infused with increasing concentrations of synthetic oxytocin (16–128 m.i.u./min for 3 h) or injected daily for a week with the same hormone (20 i.u., i.v.) and the plasma testosterone levels measured. The results of the present study show that acute infusion or chronic injection of oxytocin does not significantly affect the plasma testosterone levels, suggesting that systemic control of testicular endocrine function by oxytocin may be unimportant.