BACKGROUND/AIMS: The aim of present study is to estimate the effects of Melissa officinalis L. (MO) on visceral hypersensitivity (VH), defecation pattern and biochemical factors in 2 experimental models of irritable bowel syndrome (IBS) and the possible role of nitric oxide. METHODS: Two individual models of IBS were induced in male Wistar-albino rats. In the acetic acid model, the animals were exposed to rectal distension and abdominal withdrawal reflex, and the defecation patterns were determined. In the restraint stress model, the levels of TNF-α, myeloperoxidase, lipid peroxidation, and antioxidant powers were determined in the (removed) colon. Rats had been treated with MO, L-NG-nitroarginine methyl ester (L-NAME), aminoguanidine (AG), MO + AG, or MO + L-NAME in the mentioned experimental models. RESULTS: Hypersensitive response to rectal distension and more stool defecation in control rats have been observed in comparison to shams. MO-300 significantly reduced VH and defecation frequency in comparison to controls. VH and defecation pattern did not show significant change in AG + MO and L-NAME + MO groups compared to controls. Also, significant reduction in TNF-α, myeloperoxidase, thiobarbituric acid reactive substances (TBARS), and an increase in antioxidant power in MO-300 group was recorded compared to controls. AG + MO and L-NAME + MO groups showed a reverse pattern compared to MO-300 group. CONCLUSIONS: MO can ameliorate IBS by modulating VH and defecation patterns. Antioxidant and anti-inflammatory properties along with its effect on the nitrergic pathway seem to play important roles in its pharmacological activity.
Acetic Acid ; Animals ; Colitis ; Colon ; Defecation ; Humans ; Hypersensitivity ; Irritable Bowel Syndrome ; Lipid Peroxidation ; Male ; Melissa ; Models, Theoretical ; NG-Nitroarginine Methyl Ester ; Nitric Oxide ; Peroxidase ; Rats ; Reflex ; Thiobarbituric Acid Reactive Substances

Objective: To investigate the effect of isoimperatorin on histopathological and biochemical changes in acetic acid-induced colitis rats. Methods: Colitis was induced by intracolonic administration of acetic acid solution (4% v/v) in rats. Rats were divided into six groups including the sham group, the negative control group, the dexamethasone-treated group, and the groups treated with isoimperatorin (0.1, 1, and 10 mg/kg/d by gavage). The treatments were administered for three days and then colonic status was assessed by macroscopic, histopathological, and biochemical analyses. Results: Isoimperatorin significantly alleviated colonic damage in a dose-dependent manner and improved histological changes in rats with acetic acid-induced colitis. It also significantly reduced myeloperoxidase, TNF-α, IL-1β, and malodialdehyde levels. Conclusions: Isoimperatorin alleviates acetic acid-induced colitis in rats and may be a potential therapeutic agent for the treatment of colitis.