Influence of Progesterone on Sexual Performance in Male Rats

Abstract

It has been documented that copulatory experience can alter or improve sexual performance in male rats. However, the hormonal basis and the number of sexual encounters needed for a rat to acquire sufficient performance remains unclear. The aim of this study was to examine whether levels of testosterone and progesterone are associated with sexual performance in male rats. Adult male Wistar Hannover rats were exposed to a receptive female for 15 minutes every other day for 9 days for acquiring sexual experience. After training protocol, rats were scored as low or high sexual performers. Hormonal levels (testosterone and progesterone) were evaluated in both trained and non-trained control groups. Our results showed that a 9-day training period was not sufficient for some male rats to acquire a good level of sexual performance. While 42.5% of the rats displayed excellent sexual performance during the training sessions, 17.5% showed adequate performance, 7.5% had low sexual activity, and 32.5% of the rats did not display any sexual behaviors whatsoever. Additionally, after 4 days of training, rats with excellent/adequate performance showed a significant decrease in ejaculation latency relative to the first day of training. The rats with low or no sexual activity had lower progesterone levels relative to those displaying the highest sexual performance after 9 days of training. Testosterone, in turn, was also significantly reduced in animals with low/no sexual performance compared with excellent/adequate rats. In conclusion, progesterone may be a limiting factor to promoting sexual performance in male rats.