Evaluation of the effects of Iranian propolis on the severity of post operational-induced peritoneal adhesion in rats

Background: Peritoneal adhesion is a major complication of surgery that can lead to serious problems such as bowel obstruction, pain, infertility and even mortality. Propolis is a honey bee product with anti-inflammatory and anti-oxidant activities that could potentially protect against adhesive surgical complications. Methods: Forty 8-weeks-old rats (275 +/- 25 g) were divided into five groups: normal group without any surgical procedure, and experimental groups treated with normal saline, 50 mg/kg, 100 mg/kg and 200 mg/kg of propolis. Peritoneal adhesions were examined macroscopically and also, the levels of inflammatory factors (IL-6, IL-1 beta and TNF-alpha), growth factors (TGF-beta 1 and VEGF) were evaluated in the study groups using ELISA. Biochemical indices of oxidative status including Nitric Oxide (NO), Malondialdehyde (MDA) and Glutathione (GSH) were also measured. Results: Peritoneal adhesion scores, IL-1 beta, IL-6, TNF-alpha, TGF-beta 1, VEGF, NO, GSH and MDA levels were significantly different between the study groups (p < 0.001). Propolis treatment reduced peritoneal adhesion (p < 0.001), TNF-alpha (p < 0.001), IL-1 beta (p < 0.001), IL-6 (p < 0.001), TGF-beta 1 (p < 0.001), VEGF (p < 0.001), NO (p < 0.001) and MDA (p < 0.001), while GSH levels were increased (p < 0.001) compared with the vehicle group. Our results showed that higher dose of propolis was associated with significantly greater reductions in peritoneal adhesion (p < 0.001), TNF-alpha (p < 0.001), IL-1 beta (p < 0.001), IL-6 (p < 0.001), VEGF (p < 0.001), NO (p < 0.001) and MDA (p < 0.001), a greater increase in GSH levels (p < 0.001) compared with the lower dose. Conclusions: Propolis treatment can dose-dependently reduce peritoneal adhesion through its anti-inflammatory, anti-angiogenic and antioxidant properties. Therefore, propolis might serve as a protective agent against post-surgical adhesive complications.