Abstract
Background & aims:
Tissue injury healing is impaired in aging, and this impairment is caused in part by reduced angiogenesis. Melatonin, a neuroendocrine hormone that regulates sleep and circadian rhythm is also produced in the gastrointestinal tract. The expression of melatonin receptors - MT1 and MT2 in gastric endothelial cells, and their roles in aging-related impairment of gastric angiogenesis, have not been examined. We hypothesized that MT1 and MT2 expression is reduced in gastric endothelial cells of aging rats and that melatonin treatment can upregulate their expression and improve angiogenesis.
Methods:
We examined the expression of MT1 and MT2 in gastric endothelial cells (GECs) isolated from young and aging rats. We also examined the effects of melatonin treatment on angiogenesis, GEC mitochondrial function, expression of vascular endothelial growth factor (VEGF), its signaling receptor (VEGFR-2), and the inhibitor of apoptosis protein, survivin.
Results:
Young and aging GECs expressed MT1 (in the cytoplasm and mitochondria) and MT2 (in nucleus and mitochondria). In aging GECs, MT1 and MT2 levels, in vitro angiogenesis, and mitochondrial membrane potential were significantly reduced (by 1.5-fold, 1.9-fold, 3.1-fold, 1.63-fold, respectively) vs. young GECs. Melatonin treatment of aging GECs significantly increased MT1 and MT2 expression vs. controls, induced nuclear translocation of MT1, and significantly ameliorated the aging-related impairment of angiogenesis and mitochondrial function.
Conclusions:
Aging GECs have significantly reduced MT1 and MT2 expression, angiogenesis, and mitochondrial membrane potential vs. young GECs. Treatment of aging GECs with melatonin increases expression of VEGF receptor and survivin and ameliorates aging-related impaired angiogenesis and mitochondrial function.
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