Aging alters opiate inhibition of potassium (K+)-stimulated dopamine release from the corpus striatum of male rats.
The effect of Leu-enkephalin (Leu-ENK), Met-enkephalin (Met-ENK), and naloxone on potassium (K+)-evoked endogenous dopamine (DA) release from striatal tissue fragments was examined in young (2-4 month) and old (20-25 month) male rats. The K(+)-evoked DA release was significantly lower in old compared to young animals. Leu-ENK significantly reduced K(+)-evoked DA release in young animals, but neither opiate affected DA release in old animals. Naloxone, which had no effect in young animals, raised the K(+)-evoked DA response in old animals to levels seen in young control preparations. These results suggest that the age-dependent decrease in K(+)-evoked DA release may in part be due to a stronger opiate inhibitory tonus in the CS of older rats.
Laping
N J
NJ
University of Illinois.
Dluzen
D E
DE
Ramirez
V D
VD
D000367:Age Factors; D000375:Aging / Q000378:metabolism*; D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D004745:Enkephalins / Q000493:pharmacokinetics*; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012737:Sex Factors
D004745:Enkephalins; D009270:Naloxone; D011188:Potassium; D004298:Dopamine