Chronic isolation of adult animals represents a form of psychological stress 
that produces sympatho-adrenomedullar activation. Exercise training acts as an 
important modulator of sympatho-adrenomedullary system. This study aimed to 
investigate physical exercise-related changes in gene expression of 
catecholamine biosynthetic enzymes (tyrosine hydroxylase, dopamine-ß-hydroxylase 
and phenylethanolamine N-methyltransferase) and cyclic adenosine monophosphate 
response element-binding (CREB) in the adrenal medulla, concentrations of 
catecholamines and corticosterone (CORT) in the plasma and the weight of adrenal 
glands of chronically psychosocially stressed adult rats exposed daily to 20 min 
treadmill running for 12 weeks. Also, we examined how additional acute 
immobilization stress changes the mentioned parameters. Treadmill running did 
not result in modulation of gene expression of catecholamine synthesizing 
enzymes and it decreased the level of CREB mRNA in the adrenal medulla of 
chronically psychosocially stressed adult rats. The potentially negative 
physiological adaptations after treadmill running were recorded as increased 
concentrations of catecholamines and decreased morning CORT concentration in the 
plasma, as well as the adrenal gland hypertrophy of chronically psychosocially 
stressed rats. The additional acute immobilization stress increases gene 
expression of catecholamine biosynthetic enzymes in the adrenal medulla, as well 
as catecholamines and CORT levels in the plasma. Treadmill exercise does not 
change the activity of sympatho-adrenomedullary system of chronically 
psychosocially stressed rats.