Anatomical differences in uterine sensitivity to prostaglandin F2α and serotonin in non-pregnant rats

The ovarian steroids regulate the sensitivity of a population of uterine receptors to prostaglandin F-2alpha, serotonin and oxytocin. However, the uterine sensitivity to prostaglandin F-2alpha and oxytocin does not coincide with the estrogen-induced increase in the number of receptors. Anatomical differences affect the uterine sensitivity to agonists. We investigated whether anatomical differences between ovarian and cervical uterine regions modulate the hormone-regulated sensitivity to prostaglandin F-2alpha, serotonin and oxytocin. Non-cumulative concentration-response curves for these agonists were recorded for ovarian and cervical uterine segments from adult ovariectomized rats treated with 17beta-estradiol, 17beta-estradiol+progesterone, or vehicle. The ovarian segments displayed a higher maximal response (E-max) to prostaglandin F-2alpha and a lower E-max to serotonin than the cervical segments. Both uterine segments displayed a similar sensitivity to oxytocin. The ovariectomized controls displayed the highest E-max and the lowest effective concentration 50 (EC50) for oxytocin and prostaglandin F-2alpha. Anatomical differences between ovarian and cervical uterine regions modulate the hormonal regulation of uterine sensitivity to serotonin and prostaglandin F-2alpha in the non-pregnant rat uterus. (C) 2002 Elsevier Science B.V. All rights reserved.