Effect of prolactin on ovarian tissue-type palsminogen activator and prostaglandin E2 in superovulated rat

Kim, Kyoung Won; Sim, Jae Chul; Yang, Hoe Saeng

Abstract

OBJECTIVE
This study is to analyze the direct effects of hyperprolactinemia, cause of anovulation and infertility, on ovarian function.
METHODS
The prepubertal female Sprague-Dawley (SD) rats were obtained and ovulation was induced with PMSG and hCG s.c.. The rats were divided into four groups, which received the following treatments IP : saline 0.2 ml, 150 ug PRL, 300 ug PRL, 300 ug PRL plus 300 ug naloxone. The animals were killed and the oviducts were evaluated for the presence of ova. The ovary were then removed and evaluated under light microscopy. For changes of follicular t-PA and PGE2 concentration after PRL, immature female SD rats were stimulated as described above. At four hours after the hCG injection the rats were killed and the ovaried were removed. Each isolated ovaries were incubated in culture plate containing incubation medium or 300 ng PRL to be tested. And PRL plus gonadotropin in incubation medium was tested because of change of PGE2 concentration. After incubation period, t-PA and PGE2 were measured by EIA. Differences between groups were assessed by two-way ANOVA of variance followed Mann-Whitney U test or Kruskal-Wallis test for multiple comparisons. p<0.05 was considered statistically significant.
RESULTS
As result, prolactin transiently suppresses ovulation, especially with its increased concentration not by altering the ovarian morphology. But ovulation inhibition was reversed by naloxone injection. The level of t-PA in control and prolactin-treated group increased steadily in response to human chorionic gonadotropin administration, yet lower in prolactin-treated group. But PGE2 concentration was increased in gonadotropin mixed groups but not affected in prolactin-treated group despite a significant blockade of ovulation.
CONCLUSION
Thus, further studies on the effect of high level prolactin on ovulatory function would significantly contribute toward the patient with hyperprolactinemia for managing infertility and maintaining appropriate female reproductive function.