The ovarian and cervical regions of the rat uterus display a different contractile response to serotonin and prostaglandin F2 alpha I. The estrous cycle

In pharmacological. studies using isolated tissues, the sensitivity to diff erent agonists may vary depending on the anatomical region. The aim of the present study was to evaluate the in vitro contractile response to serotoni n, prostaglandin F-2 alpha, and oxytocin of the ovarian and the cervical ut erine segments isolated from rats in the four different stages of the rat e strous cycle. Non-cumulative curves were recorded for both, the ovarian and the cervical uterine segments. The cervical portion displayed a higher con tractile response to serotonin and a lower response to PGF(2 alpha) than th e ovarian portion. Oxytocin induced similar responses in both uterine segme nts. The uterine ovarian segment displayed a similar sensitivity to seroton in in all the estrous cycle stages, whereas in the cervical segment, influe nced by estrogens in diestrus and proestrus, an increase in contractility w as observed. According to these findings, serotonin might participate in th e spermatozoa transport toward the oviduct. The higher response of the ovar ian portion to prostaglandin F-2 alpha is in line with its role during labo r and delivery. (C) 2000 Elsevier Science Inc.