Response of testosterone to hemicastration in the testicular vein of the mature rat.

Abstract

A rapid procedure was developed and validated for collection of testicular vein blood from rats. Samples were collected from both testes and the heart within 2-5 min of transfer of the rat to the anaesthesia jar. There was no difference in levels of testosterone in testicular vein serum between successive samples from the same testis or alternate samples from paired testes. Both hemicastration and sham-hemicastration significantly depressed levels of testosterone in testicular vein serum 4 h after surgery. Peripheral serum testosterone levels were significantly depressed after hemicastration but not sham-hemicastration at 4 h after surgery. By 24 h after surgery, testosterone in testicular vein serum was doubled in the hemicastrated rat, and was restored in the sham-hemicastrated rat, thus achieving normal peripheral testosterone levels in both groups. Similar results were observed in bilaterally denervated rats. These rapid changes could not be attributed to serum LH, which maintained steady levels during the course of these experiments. It was concluded that there are two components in the response to hemicastration: a non-specific response within 4 h to sham-surgery or any other disturbance to the animal, which depresses testosterone output sharply, and a specific response within 24 h to hemicastration, which doubles testicular output. It is the non-specific response after sham-surgery which has simulated and obfuscated the response to hemicastration in the male rat.