Restriction and functional changes of dopamine release in rat striatum from young adult and old rats.
In order to investigate the age-related changes in dopaminergic activity in rats, we have utilized the K(+)- and veratridine-stimulated [14C]dopamine release from striatum in vitro as a functional index of responsiveness to these stimuli in aging. We found that the K(+)-stimulated dopamine release from old (12 months) rats decreased by more than 50% compared to that from young adult rats (3 months). Reserpine (5 mg/kg) led to a pronounced decrease of the K(+)-stimulated dopamine release of young adult as well as old rats. Whereas ouabain (10 mumol/l) decreased the K(+)-stimulated dopamine release from young adult rats, in old rats the K(+)-induced dopamine release was increased up to 250%. However, in old rats which were reserpine pretreated, ouabain was unable to stimulate the K(+)-induced dopamine release. In contrast, the veratridine-stimulated dopamine release of old rats was increased up to 200% compared to that of young adult rats and was highly sensitive to reserpine pretreatment but not to ouabain. However, reserpine did not alter this veratridine-stimulated dopamine release from young adult rats. The present data indicate that the age-related reduction of exocytosis-related, Ca(2+)-dependent release mechanisms (K+) are probably compensated via an increase in Ca(2+)-independent, uptake carrier-mediated release processes (veratridine).
Dobrev
D
D
Institute of Pharmacology and Toxicology, Medical Faculty, Technical University Dresden, Germany.
Bergsträsser
E
E
Fischer
H D
HD
Andreas
K
K
D000367:Age Factors; D000375:Aging / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D003342:Corpus Striatum / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012110:Reserpine / Q000494:pharmacology; D014701:Veratridine / Q000494:pharmacology
D010042:Ouabain; D014701:Veratridine; D012110:Reserpine; D011188:Potassium; D002118:Calcium; D004298:Dopamine