The effect of administration of bee propolis in different periods of pregnancy on rat placenta histomorphometry

Background and Objective: Propolis is a resinous substance produced by honeybees that possess many biological activities, such as antitumor, antioxidant, antimicrobial, anti-inflammatory, and immunomodulatory, among others. The purpose of the present study was to investigate the placental histomorphometric changes of propolis-treated rats to observe whether propolis might lead to side effects after administration. Materials and Methods: A total of twenty-four Wistar rats were grouped into four groups including (۱) control, (۲) rats were treated with propolis from ۷ to ۱۳ days of gestation, (۳) rats were treated with propolis from ۱۴ to ۲۰ days of gestation, and (۴) rats were treated with propolis from ۷ to ۲۰ day of gestation. For sampling, at the ۲۰th day of gestation, the rats were euthanized, then the uterus was removed, and the placentas were separated from the uterus. Immediately placental morphometric examinations including placental weight, diameter, and thickness were performed. General and specific staining was used for histological examinations and then the samples were evaluated by light microscopy. Results: Administration of propolis between the ۷th-۱۳th and ۷th-۲۰th days of gestation significantly increased placental weight, diameter, thickness, the number of giant cells, and the thickness of labyrinth and spongiosum layers compared to the control group (P ۰.۰۵). Also, propolis significantly reduced the number of glycogen cells and the thickness of the decidua in the placenta (P ۰.۰۵). Conclusion: On the basis of our findings, the administration of bee propolis altered the normal values of some placental parameters in rats. Clinical application of bee propolis should therefore be carefully controlled as its administration may be relatively unsafe for the integrity of organs.