Estrogen and androgen dynamics in the cynomolgus monkey

Area of Science:

• Endocrinology
• Primate Physiology
• Comparative Metabolism

Background:

• Hormone dynamics vary across species, impacting research applicability.
• Cynomolgus monkeys are a key model for human physiological studies.
• Understanding steroid hormone metabolism is vital for endocrine research.

Purpose of the Study:

• To establish baseline data for androgen, estrogen, and cortisol dynamics in male cynomolgus monkeys.
• To compare these hormonal parameters with those in other primate species, including humans.
• To investigate steroid hormone production, metabolism, and protein binding in vivo.

Main Methods:

• Constant infusion of radiolabeled androgens, estrogens, and cortisol in 11 male cynomolgus monkeys.
• Collection of peripheral and hepatic vein blood samples, and urine over 96 hours.
• Analysis of radioactivity in blood and urine for specific steroid hormones and measurement of protein binding.

Main Results:

• Mean clearance rates (MCRs) and blood production rates for testosterone, androstenedione, estradiol, estrone, and cortisol were determined.
• Aromatization rates from androgens to estrogens were quantified.
• Differences in free hormone percentages and binding globulin concentrations were observed, with cortisol showing higher free fractions.

Conclusions:

• Steroid hormone dynamics in male cynomolgus monkeys closely resemble those in humans and other primates.
• Peripheral aromatization shows particular similarity between humans and nonhuman primates.
• The data provide a valuable reference for comparative endocrinology and nonhuman primate research.