Salivary testosterone levels in normal and testosterone treated monkeys

Testosterone concentrations in saliva and matched serum samples were measured by radioimmunoassay, in normal and testosterone treated adult male cynomolgus monkeys (Macaca fascicularis) and in untreated rhesus monkeys (Macaca mulatta). Saliva and serum samples were collected under ketamine anaesthesia. In 4 cynomolgus monkeys, the mean basal testosterone levels were 195 +/- 22 pmol/l in saliva and 24 +/- 2 nmol/l in serum (n = 17). The salivary testosterone corresponded to 0.9 +/- 0.1% of the serum testosterone concentration. In 5 rhesus monkeys the mean testosterone concentrations were 147 +/- 10 pmol/l in saliva and 17 +/- 2 nmol/l in matched serum samples with a percent ratio of 1.6 +/- 0.3 (n = 15). Following a single i.m. injection of 50 mg testosterone propionate to 4 monkeys, both salivary and serum testosterone levels increased promptly and in parallel. The salivary testosterone levels correlated well with the serum testosterone values. The study suggests that, as in the human, determination of salivary testosterone can be used as an index of free testosterone in this animal. Moreover, the monkey can be used as a model for studies in the human involving monitoring of salivary testosterone.