Induction of matrix metalloproteinase-9 and -3 in nonsteroidal anti-inflammatory drug-induced acute gastric ulcers in mice: regulation by melatonin.

The pathogenesis of gastric ulcer is associated with remodeling of extracellular matrix (ECM) by various matrix metalloproteinases (MMPs). However, how MMPs are regulated during nonsteroidal anti-inflammatory drug (NSAID)-induced acute gastric ulceration is not well studied. In this study, different NSAIDs (80 mg/kg b.w.) were applied to generate acute gastric ulcer in the BALB/c mouse and the regulation of MMPs were investigated. NSAIDs caused dose-dependent induction in MMP-9 and -3 activities and expressions in ulcerated gastric tissues along with significant infiltration of inflammatory cells and disruption of gastric mucosal layer. In addition, an increase in tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-8 expression, excessive generation of hydroxyl radical ((*)OH), and protein oxidation and lipid peroxidation were observed in acute ulcerated gastric tissues. In this study, the efficacy of melatonin on activities of MMP-9 and -3 during prevention of gastric ulcers was tested. Melatonin at a dose of 60 mg/kg b.w. downregulated MMP-9 and -3 both at the enzyme and protein levels in mouse gastric tissues during prevention as well as healing of acute gastric ulcers. It also blocked oxidative stress via inhibition of protein oxidation, lipid peroxidation, (*)OH generation and SOD-2 expression. Moreover, it suppressed myeloperoxidase activity and expressions of TNF-alpha, IL-1beta and IL-8. This study documents for the first time that induction of MMP-9 and -3 activities accompany NSAID-induced inflammation and oxidative stress in gastric tissues and indicates that, melatonin may be a preventive or therapeutic remedy for gastric ulcers.