Dietary restriction alters the “in vitro” spontaneous or oxytocin-induced contractions of uterine smooth muscle from estrous rats. Possible participation of prostaglandins

Abstract

Rats subjected to a restricted-diet (50% of the normal intake for 15 days) presented a progressive reduction of body weight. The isometric developed tension (IDT) of uterine horns obtained from these animals during estrus exhibited greater initial (postisolation) values and a better constancy with time than preparations from normal-fed controls. The enhanced contractions were diminished after a refeeding period of 6 days as well as following the addition into the suspending medium of inhibitors of cyclo-oxygenase (indomethacin or acetylsalicylic acid). Cumulative dose-response curves to oxytocin documented a greater sensitivity in uterine horns from restricted-diet rats than in those from controls or refed animals. The output of prostaglandin (PG) E 2 but not that of PGF 2α into the external solution was significantly higher (P < 0.001) in the case of uterine tissue from restricted-diet rats than in normal fed controls. The findings suggest that changes in IDT evoked by partial starvation are associated with the enhanced generation of some PGs by the uterus.