Differential Gene Expression of Tyrosine Hydroxylase in Rats Exposed Long-Term to Various Stressors

Activity of the sympathetic-adrenomedullary system (SAS) in rats exposed to heterotypic novel stressors after prior chronic stress exposure is poorly understood. A potentiation of SAS activity evaluated by plasma catecholamine levels in chronically stressed rats exposed to novel stressors has been reported (Dronjak et al., 2001). The exaggerated effect of novel stressors is an interesting phenomenon, but its mechanism at the level of adrenomedullary gene expression of catecholamine biosynthetic enzymes is not known.