PARENT SESSION
BIOLOGY OF THE MALE REPRODUCTIVE TRACT
Harborside C
7:30 AM-10:00 AM

(572) NEONATAL OXYTOCIN AFFECTS REPRODUCTION IN MALE PRAIRIE VOLES.

Abdelnabi, Mahmoud¹, Bales, Karen², Ottinger, Mary Ann¹, Carter, C. Sue², ¹ Department of Animal and Avian Sciences, College Park, MD² Department of Psychiatry, Chicago, IL

ABSTRACT- Oxytocin is closely associated with reproduction in male mammals, especially with sperm transport. The purpose of this study was to study long term effects of neonatal exposure to oxytocin on male reproductive performance in male prairie voles. Within 24 hours of birth, 58 male prairie voles (Microtus ochrogaster) were randomly divided into 4 groups and received either 0.3 ug oxytocin (OT), 0.3 ug oxytocin antagonist (OTA), isotonic saline solution (SAL) or were handled only (HO) without injection. At 6-8 months of age, males were paired with an estrus female, behavior was observed, and females were lavaged to determine the presence of sperm. Males were sacrificed by cervical dislocation and the testes, epididymis, seminal vesicles, and prostate were weighed. Sperm were collected from the epididymis for determination of sperm concentration and motility. The left testis was fixed in Bouin's solution for histology. Results showed no difference in frequency of ejaculation; however, both treatments were associated with reduced likelihood of sperm transfer to the female (p=0.04). No differences were found in body weight, testes weight, and accessory gland weights. Epididymal sperm motility was similar across treatments. Testicular spermatogenesis was evaluated using Berg's stain; area containing developing sperm was assessed by image analysis. HO males had slightly higher epididymal sperm concentration and low area (48.8 x 10⁶/mg epididymis; 6.64 x 10^-4/mm²). OTA animals had the lowest concentration and highest testicular sperm cell area (17.4 x 10⁶/mg epididymis; 7.86 x 10⁴mm²). These data provide data showing neonatal OT or OTA exposure both have long term effects on later reproductive capacity. Further, there appear to be deleterious effects of both treatments, suggesting that some threshold level of OT is needed for appropriate development of the male reproductive system, with potential damaging effects also from elevated exposure at this time. Supported by HD 38490.

KEY WORDS: male reproduction, neonatal oxytocin, spermatogenesis, reproductive behavior