Effects of phenolic acids on gastrointestinal smooth muscle complications in streptozotocine-induced diabetic rats

Aim: To identify the effects of antioxidants on gastrointestinal smooth muscle complications in 6-week streptozotocine (STZ)-induced diabetic rats. Materials and methods: The following steps were carried out: 1. Three weeks after STZ injection, saline and 10 mg/kg p-OH benzoic, protocatechic, and gallic acids were separately administered to the rat groups every day for 3 weeks. 2. The responses of the fundus and ileum to agonists were recorded using isolated organ bath experiments. Results: Diabetic smooth muscle complications developed in the diabetic rats. The responses of the ileum to acetylcholine increased whereas the responses of the fundus to serotonine decreased in the diabetic rats. The test drugs inhibited and promoted but did not affect the smooth muscle complications in the diabetic rats, and sometimes they aff ected the smooth muscle activity, which did not change with diabetes. Conclusion: The antioxidants used elicited pro-oxidant activation and/or exhibited effects independent of diabetic complications of gastrointestinal smooth muscles in the experimental conditions applied.