The effect of morphine administration on structure and ultrastructure of uterus in pregnant mice

Background: Maternally administered opiates such as morphine represent a serious human health problem. Opioid abuse may have unfavorable effects on reproductive organs. Objective: The present study evaluates on the effects of morphine on structure and ultrastructure of uterus in BALB/c mice. Materials and Methods: Forty BALB/c pregnant mice were divided into four groups: two experimental (I and II), one sham and one control group. 5 mg/kg and 10 mg/kg morphine were injected via intra-peritoneal (IP) route, daily (during 15 days) in group I and II animals, respectively. The same volume of saline was administrated in sham group. Control group did not receive any treatment. At 15th day of gestation (E15), the pregnant mice were sacrificed and their uterus was removed. Following histochemical staining, the samples were studied using light and transmission electron microcopies. Results: In experimental groups, some apoptic sites with polymorphic inflammatory infiltration and congestion of vessels were observed. The rate of polymorphic inflammatory infiltration and apoptic sites were 60% and 70% in experimental groups I and II, respectively. Also, the rate of vessel congestion in the experimental groups (I and II) was 70%. The ultrastructural study showed the nuclear membranes of endometrial epithelial cell was torn, convoluted, and a distance between nuclei and irregular chromatin was observed in both experimental groups. There were no signs of structural abnormalities in other groups. Conclusion: Morphine administration causes histological and cytological lesions that may be responsible for endometrial alterations in laboratory animals.