Expression of oxytocin receptors in the uterine junctional zone in women with adenomyosis

OBJECTIVE: To compare the expression of oxytocin receptor in the uterine junctional zone of the fundus and isthmus in the proliferative and secretory phases in women with and without adenomyosis. DESIGN: Experimental prospective clinical study. SETTING: Tertiary gynecologic medical center. POPULATION: Twenty-nine women with adenomyosis (15 in proliferative phase, 14 in secretory phase) and 27 women without adenomyosis (15 in proliferative phase, 12 in secretory phase). METHODS: Samples from the uterine fundus and isthmus were obtained at hysterectomy. The expression of oxytocin receptor was evaluated using immunohistochemistry. MAIN OUTCOME MEASURES: Immuno-reactive score was used evaluate semi-quantitatively the oxytocin receptor expression. RESULTS: In normal uteri, the expression of oxytocin receptor in the isthmus was significantly higher than in the fundus in the proliferative phase (p < 0.01) but the opposite distribution pattern was observed in the secretory phase. Conversely, in adenomyosis uteri, the expression of oxytocin receptor in the fundus was significantly higher than in the isthmus in the proliferative phase (p < 0.05); however, this difference was not significant in the secretory phase. Moreover, oxytocin receptor expression in the fundus of adenomyosis uteri was higher than that in the control uteri in both the proliferative and secretory phases. CONCLUSIONS: The expression pattern of oxytocin receptor in the normal junctional zone is disrupted in women with adenomyosis. This may be one possible explanation for the symptomatology of the condition.