title: Aging alters opiate inhibition of potassium (K+)-stimulated dopamine release from the corpus striatum of male rats.
abstract: 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.
authors.affiliation: University of Illinois.
authors.forename: N J
authors.initials: NJ
authors.lastname: Laping
authors.forename: D E
authors.initials: DE
authors.lastname: Dluzen
authors.forename: V D
authors.initials: VD
authors.lastname: Ramirez
mesh_terms: 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
chemical_list: D004745:Enkephalins; D009270:Naloxone; D011188:Potassium; D004298:Dopamine