The stimulation of testosterone and LH secretion by synthetic GnRH in the male Cape porcupine

Abstract

The effects of GnRH stimulation on plasma testosterone and luteinizing hormone (LH) levels in Cape porcupine males were examined by analysing plasma collected before and after an intravenous injection of GnRH. In six mature males and one subadult, which were given an intravenous injection of 0,5 ml saline, levels of plasma testosterone and LH did not increase. Four weeks later an intravenous GnRH challenge (40 μg) caused plasma testosterone to rise three-fold and LH to rise 10-15-fold within 180 min in five of the mature males. Peaks of plasma testosterone and LH occurred 90 and 120 min, respectively, after stimulation, and baseline and peak levels of both hormones were significantly related.