Plasma oxytocin and estradiol in pelvic neurectomized rats with blocked parturition.

To determine if oxytocin and estradiol were effected by pelvic neurectomy (PN), utero-ovarian vein blood was collected from PN rats during the preparturient period and assayed for these hormones. Radioimmunoassayable oxytocin levels were not significantly different in any groups of sham operated (S) or PN animals on days 21 and 22 or PN animals on days 23 and 24. Estradiol (E2) levels rose significantly on day 22 in S animals but there was no significant change in E2 in PN rats throughout the time period studied, although E2 levels were generally high. These results indicate that the blocked parturition characteristic of PN animals cannot be attributed to altered oxytocin levels. The lack of a significant E2 surge on day 22 in PN rats may contribute to the failure of utero-ovarian vein prostaglandin F levels to rise in these animals during the preparturient period.