ABSTRACT
Changes induced by physical training were examined by in vivo microdialysis monitoring of extracellular dopamine and its metabolites in the rat nucleus accumbens, and by an immunohistochemical staining for fos protein as an index of nerve cell excitation.<BR>The exercise training consisted of running on a treadmill 5 days/week for 4 weeks, with gradually increasing the running speed from 10 to 20 m/min for 20 min. The control group performed forced treadmill running for 3 days.<BR>The sulpiride-induced increase in both dopamine release and dopamine metabolism was significantly attenuated in the nucleus accumbens of training rats in comparison with the controls, which indicated that physical training induced subsensitive DA D<SUB>2</SUB> receptors in the central dopaminergic neurons.<BR>Fos protein expression following 1 h running was weaker in neurons of the raphe dorsalis, the locus ceruleus and the amygdala of trained rats than in those of controls. The present findings suggest that both neurochemical response to various stimuli, and adaptation induced by physical training differ from those in untrained animals.