Effects of genitofemoral nerve transection on copulatory behavior and fertility in male rats

Abstract

Selective transection of peripheral nerves that innervate the pelvic region results in the alteration of some aspects of copulatory behavior, including seminal plug weight. Both branches of the genitofemoral nerve primarily innervate the cremaster muscle although the genital branch has a wide distribution in the cremasteric sac. Thermoregulation of spermatogenesis and the mechanical event of ejaculation largely depend on cremaster contractility. In this study, we analyzed the effects of bilateral transection of the genitofemoral nerve on male copulatory behavior and on fertility. Sexually experienced adult male rats were submitted to sexual behavior tests before and after surgical transection of the genitofemoral nerve. Tests were made four times before and on Days 9, 12, 15, 18 and 21 after surgery, and seminal plug weight was also analyzed. In addition, fertility was tested using two different approaches: by allowing the male to ejaculate once in an estrous female or keeping the male with three females during 15 days. Results showed that there were no differences in any of the copulatory parameters, including seminal plug weight. Regarding fertility, both procedures showed that the ability to induce pregnancy was significantly diminished in the neurectomized males tested at different times after surgery. These results support the notion that genitofemoral nerve regulation of fertility via contraction of the male cremaster muscle is an important factor in reproduction in rats.