Challenge with ovalbumin antigen increases uterine and cervical contractile activity in sensitized guinea pigs

Objective: The aims of this study were to investigate the effects of ovalbumin challenge on uterine and cervical contractility, intrauterine pressure, and uterine electromyography activity in sensitized guinea pigs. Study Design: Guinea pigs were sensitized by injection of ovalbumin-aluminum hydroxide suspension. Control animals were injected with the aluminum hydroxide suspension only. On days 55-57 of pregnancy, longitudinal uterine and cervical strips from guinea pigs were prepared for isometric tension recording. Nonpregnant guinea pigs were outfitted with telemetric transducers to record intrauterine pressure and uterine electromyography. Results: Ovalbumin significantly increased contractility of uterine and cervical strips from sensitized versus nonsensitized animals. These effects were abolished by histamine H₁ receptor antagonist in uterine strips and by histamine H₁ receptor antagonist and a mast cell stabilizer in cervical strips from sensitized animals. Cyclooxygenase and 5-lipoxygenase inhibitors had no significant effect on the response to ovalbumin. Treatment with ovalbumin in vivo significantly increased intrauterine pressure and uterine electromyography activity in sensitized but not in nonsensitized, animals. Conclusion: Our findings indicate that type I hypersensitivity reactions may be important in mediating uterine contractility in pregnant and nonpregnant states.