Heme oxygenase-1 expression and oxidative stress - related markers in gastric mucosa in skin burns and protection with melatonin

Melatonin, a major hormone of pineal gland, was recently show to attenuate acute gastric lesions induced by strong irritants because of the scavenging of free radicals. The effect of melatonin on burninduced gastric mucosal injury due to the skin burn is unclear. PURPOSE: This study investigated heme oxygenase-1 and markers linked with oxidative stress in gastric mucosa and the effect of melatonin in burn rat model. METHODS: Melatonin was applied immediately and 12 hours after 30% of total body surface area burns. Using light immunohistochemistry the expression of gastric mucosal inducible nitric oxide synthase (iNOS) and heme oxygenase (HO-1) was found out. Malondialdehyde (MDA) as a marker of oxidative injury was determined in gastric mucosa by the thiobarbituric acid method. RESULTS: Gastric MDA and iNOS levels were increased significantly after severe burn (p<0.05, p<0.0001, respectively). The increased HO-1 expression in the burned group was found out (p<0.05). Melatonin restricted the increased MDA (p<0.05) and iNOS (p<0.05) levels, and augmented the increase in HO-1 expression in gastric mucosa (p<0.05). In conclusion, melatonin ameliorates gastric mucosal injury via induction of antioxidant enzyme HO-1 and inhibition of oxidative stress beyond local burn skin injury.