The K(+)-evoked release of [3H]acetylcholine from slices of rat globus pallidus: modulation by delta-opioid receptors.
Previous investigations have shown that the activation of delta-opioid receptors depresses the release of acetylcholine (ACh) in the rat caudate putamen. This finding raised the possibility that the release of ACh is similarly modulated in the globus pallidus, a region containing a distinct population of cholinergic neurons and enriched in enkephalinergic nerve terminals. In the present study the pallidal release of ACh was characterized and the effects of delta-opioid receptor activation on this release were examined. The results show that this release is stimulated by high K+ in a concentration- and Ca(2+)-dependent manner. D-Pen2,L-Pen5-enkephalin (0.1-10 microM), a selective delta-opioid receptor agonist, produced a dose-related inhibition of the 25 mM K(+)-evoked tritium release. The maximal inhibitory effect, representing a 34% decrease in the K(+)-induced tritium release, was observed at a concentration of 1 microM. This opioid effect was attenuated by the selective delta-opioid receptor antagonist, ICI 174864 (1 microM). These findings support the role of a delta-opioid receptor in the modulation of ACh release in the rat globus pallidus.
Ruzicka
B B
BB
Department of Pharmacology and Toxicology, Queen's University, Kingston, Ont., Canada.
Jhamandas
K
K
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D020881:Enkephalin, D-Penicillamine (2,5)-; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D004745:Enkephalins / Q000494:pharmacology; D005917:Globus Pallidus / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D009292:Narcotic Antagonists / Q000494:pharmacology; D010830:Physostigmine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects / Q000378:metabolism*; D017465:Receptors, Opioid, delta
D004745:Enkephalins; D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D004743:Enkephalin, Leucine; D020881:Enkephalin, D-Penicillamine (2,5)-; C040643:N,N-diallyl-tyrosyl-alpha-aminoisobutyric acid-phenylalanyl-leucine; D010830:Physostigmine; D002795:Choline O-Acetyltransferase; D000109:Acetylcholine; D011188:Potassium