The effect of L-dopa upon in vitro dopamine release from the corpus striatum of young and old male rats.
In the present experiments, we examined the effects of superfusion of L-DOPA upon in vitro dopamine (DA) release from the corpus striatum (CS) in young (2-4 months) and old (24 months) male rats. In Experiment I, responses to two successive increasing doses of L-DOPA (1.0 and 10 microM) indicated a clear age difference with DA release from CS of young rats significantly greater than that of old rats in response to the 10 microM dose of L-DOPA. Interestingly, CS fragments of young and old male rats responded marginally to the 1.0 microM L-DOPA infusion, and no significant differences between these two age groups were obtained. Since we have previously observed that the addition of naloxone to the superfusion medium restored the potassium stimulated DA release of old rats to that of young rats, in Experiment II, responses of CS tissue fragments of young and old rats superfused in medium with or without naloxone (100 microM) were tested with a single 10 microM L-DOPA infusion. The results of Experiment II indicated that the addition of naloxone to the superfusion medium did not alter the responses of CS tissue to L-DOPA in either young or old rats; however, the overall response of the young rats remained significantly greater than that of the old rats. Taken together, these results demonstrate a significant age-related decrement in the capacity of 10 microM L-DOPA to stimulate DA release from CS fragments.(ABSTRACT TRUNCATED AT 250 WORDS)
Dluzen
D E
DE
Department of Physiology, University of Illinois, Urbana 61801.
McDermott
J L
JL
Ramirez
V D
VD
D000375:Aging / Q000378:metabolism*; D000818:Animals; D003342:Corpus Striatum / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D066298:In Vitro Techniques; D007980:Levodopa / Q000494:pharmacology*; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D009270:Naloxone; D007980:Levodopa; D004298:Dopamine