[en] Extracellular single-cell recordings were performed on rat brain slices to compare the effects of morphine on noradrenergic neurons of the locus coeruleus (LC) and on dopaminergic neurons of the ventral tegmental area (VTA). Morphine inhibited the firing of LC neurons at very low concentrations. The mean IC50 was 13.4 +/- 1nM (mean +/- SEM) (n = 7). Moreover, the inhibitory effect of morphine was identical in slices obtained from rats anesthetized with chloral hydrate or from non-anesthetized rats. On the contrary, morphine did not have any influence on the firing of most VTA neurons (N = 20) up to 100 microM, and did not modify the sensitivity of their autoreceptors (N = 8). It is concluded that morphine potently inhibits the firing of LC neurons in vitro both in slices of anesthetized and not anesthetized animals and has no direct excitatory effect on VTA dopaminergic neurons of the rat.
Disciplines :
Pharmacy, pharmacology & toxicology
Author, co-author :
Seutin, Vincent ; Université de Liège - ULiège > Département des sciences biomédicales et précliniques > Pharmacologie
Franchimont, Nathalie
Massotte, Laurent ; Université de Liège - ULiège > Département des sciences biomédicales et précliniques > Département des sciences biomédicales et précliniques
Dresse, Albert ; Université de Liège - ULiège > Services généraux (Faculté de médecine) > Relations académiques et scientifiques (Médecine)
Language :
English
Title :
Comparison of the Effect of Morphine on Locus Coeruleus Noradrenergic and Ventral Tegmental Area Dopaminergic Neurons in Vitro
Seutin, Verbanck, Massotte, Dresse (1990) Evidence for the presence of N-methyl-D-aspartate receptors in the ventral tegmental area of the rat: an electrophysiological in vitro study. Brain Res, (in press); .