Gene Expression of Catecholamine Synthesizing Enzymes in Stellate Ganglia of Stressed Rats

Abstract

Enhanced activation of sympathetic neurons during stress results in an increased cardiovascular function. Social isolation is a psychological stress which has deleterious effects on health and represents the most relevant cause of diseases in mammalian species. In this study we investigated the changes in catecholamine biosynthetic enzymes tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT) gene expression and protein levels in the stellate ganglia of naive controls and chronically socially isolated (12 weeks) adult rats and the response of these animals to additional immobilization stress (2 h) by applying TaqMan RT-PCR assay and Western blot analysis. Psychosocial stress produced a significant increase of both TH mRNA (p LT 0.05) and DBH mRNA (p LT 0.05) levels in stellate ganglia. The exposure of control rats to acute immobilization significantly increased TH mRNA (p LT 0.001) and DBH mRNA (p LT 0.01) levels, while additional immobilization of chronic psychosocially stressed rats expressed no effect on gene expression of these enzymes. Protein levels of TH, and DBH remained unchanged in control and chronic social isolation rats and also after short-term immobilization. The results presented here suggest that psychosocial stress-induced an increase in gene expression of catecholamine biosynthetic enzymes in stellate ganglia and thus may be connected to the increased risk of cardiovascular disease.