Melatonin treatment affects changes in adrenal gene expression of catecholamine biosynthesizing enzymes and norepinephrine transporter in the rat model of chronic stress-induced depression.

This study investigated the effects of melatonin treatment on adrenal catecholamine content, synthesis, uptake and vesicular transport induced by the chronic unpredictable mild stress (CUMS) model of depression in rats. This entailed quantifying the norepinephrine, epinephrine, mRNA and protein levels of tyrosine hydroxylase (TH), dopamine-b-hydroxylase (DBH), phenylethanolamine N-methyltransferase (PNMT), norepinephrine transporter (NET) and vesicular monoamine transporter 2 (VMAT2) in the adrenal medulla. CUMS caused a significant depletion of norepinephrine stores and protein levels of TH, DBH and NET, whereas the gene expression of PNMT was increased. It was observed that melatonin treatment in the CUMS rats prevented the stress-induced decrease in norepinephrine content and the protein expression of TH, DBH and NET in the adrenal medulla of chronically stressed rats. The present study demonstrates the stimulatory effect of melatonin on adreno-medullary synthesis, the uptake and content of catecholamine in the rate model of chronic stress-induced depression.