Effect of Anesthetics on Testosterone Production in Rats

Abstract

Changes in testicular vein and peripheral testosterone concentrations in mature rats were monitored during anesthesia with six different agents. Samples taken 2–3 minutes after initial disturbance of the resting animal yielded mean testicular vein testosterone levels of 59–247 ng/ml plasma in nine separate groups of rats. Sustained anesthesia under halothane, enflurane, pentobarbital, ether, urethan, or ketamine/promazine resulted in a decline in testicular vein testosterone to 10–60 ng/ml by the third hour. Luteinizing hormone levels, measured under enflurane anesthesia, also fell significantly by 1 and 2 hours after administration of anesthesia, although follicle‐stimulating hormone remained constant. Testes of the enflurane‐anesthetized rat were still able to respond to gonadotropins, but withdrawal of the anesthetic did not reverse the downward trend in testosterone. No changes in testicular blood flow were detected during anesthesia, although flow under urethan anesthesia was consistently slower than with other agents. The first 90 minutes of urethan anesthesia were characterized by severe fluctuations in testicular vein testosterone. Halothane, enflurane, and pentobarbital resulted in a larger ratio of peripheral to testicular vein testosterone compared with ether or rapid sampling, suggesting a reduction in turnover rate under these three agents. Conclusions were that different anesthetic agents can distort hormone levels and endocrine function of the testes in various ways, and that the production rate of testosterone by rat testes is higher than has been previously suggested. 1980 American Society of Andrology