Melatonin rescues swim stress induced gastric ulceration by inhibiting matrix metalloproteinase-3 via down-regulation of inflammatory signaling cascade.

AIM

This study investigated the link between forced swim induced acute gastric ulceration, inflammation and MMP-3 along with the possible mechanism of protective efficacy of melatonin.

MAIN METHODS

We distributed Balb/c mice into four different groups. Group 1 and 2 were given PBS gavage. Group 3 and 4 were given melatonin (60 mg/kg b.wt.) and omeprazole (25 mg/kg b.wt.), respectively, an hour prior to forced swim. Ulcer index, tissue histology, immunohistochemistry, protein carbonylation, lipid peroxidation, Myeloperoxidase, Zymography, Western blotting, reactive oxygen species (ROS), mitochondrial dehydrogenase, mitochondrial transmembrane potential and bioinformatical analysis were performed.

KEY FINDINGS

Our data revealed that gastric ulceration due to forced swim stress is responsible for overproduction of ROS, which may be a prime reason for mitochondrial dysfunction and induction of apoptosis via activation of Caspase-3. ROS is also responsible for p38 phosphorylation which in turn increases the activity of MMP-3 in ulcerated milieu, along with the oxidation of proteins, peroxidation of lipids and altered expression patterns of heat shock protein (HSP)-70. Melatonin is shown to reduce the inflammatory burden in gastric milieu and offers gastroprotection by binding to the active site of MMP-3; thereby inhibiting its activity, as suggested by in silico studies. Melatonin also inhibits the downregulation of HSP-70 and activates p38 dephosphorylation and thereby, it rescues gastric mucosal cells from stress-induced ulceration.

SIGNIFICANCE

Our findings suggest that, melatonin imparts its gastroprotective effect by down-regulating the activation of MAPK-ERK pathway along with binding to the active site of MMP-3.