Decreased normorphine sensitivity of maternal guinea pig ilea at parturition.
Several approaches have been used by others to explore the possible involvement of endorphins in pregnancy and parturition. We employed the opioid sensitive preparation, the guinea pig ileum, to measure opioid sensitivity in three groups of adult guinea pigs: non-pregnant, near parturition, and a few weeks after parturition. Elevated normorphine EC50s occurred near the time of parturition. At 14-16 days post-partum, the EC50s for normorphine had returned to non-pregnant control levels. These data point to the activation of endorphin systems at the time of parturition.
D000818:Animals; D005260:Female; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects*; D007743:Labor, Obstetric; D008297:Male; D009022:Morphine Derivatives / Q000494:pharmacology*; D011247:Pregnancy
D009022:Morphine Derivatives; C010616:normorphine