Naloxone-induced jumping activity in morphine-dependent mice: a pharmacological study on the role of DA2 receptors.
The morphine withdrawal syndrome is strictly related to modifications on neurotransmittorial systems at central and peripheral levels. Dopamine seems to play an important role. Particularly in the experimental withdrawal syndrome the jumping activity seems to be related to a hypersensitivity of DA receptors. While the role of DA1 receptors has been extensively studied, using agonist and antagonist drugs, the role of DA2 receptors is still little known. In our study we evaluated the changes of the jumping response that was induced by substances active on DA2 receptors (lisuride, tiapride) in mice made acutely dependent on morphine, in which we induced a withdrawal syndrome with naloxone. Haloperidol (DA1-DA2 blocker) did not provoke significant changes. Either tiapride or lisuride determined a sharp increase of jumping.
D000818:Animals; D004361:Drug Tolerance; D006220:Haloperidol / Q000494:pharmacology; D008090:Lisuride / Q000494:pharmacology; D008297:Male; D051379:Mice; D009020:Morphine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects*; D009270:Naloxone / Q000494:pharmacology*; D011954:Receptors, Dopamine / Q000378:metabolism*; D013976:Tiapamil Hydrochloride / Q000494:pharmacology
D011954:Receptors, Dopamine; D009270:Naloxone; D009020:Morphine; D008090:Lisuride; D006220:Haloperidol; D013976:Tiapamil Hydrochloride