The influence of central administration of dopaminergic and cholinergic agents on morphine-induced amnesia in morphine-sensitized mice.
In the present study, effects of intracerebroventricular (i.c.v.) injections of dopaminergic and cholinergic agents on morphine-induced amnesia in morphine-sensitized mice were investigated by using a one-trial passive avoidance task. Amnesia induced by pre-training morphine was significantly reversed in morphine-sensitized mice, which had previously received once daily injections of morphine (20 and 30 mg/kg, s.c.) for 3 days. Three daily injections of SKF 38393 (1, 2 and 4 g/mouse, i.c.v.) or SCH 23390 (0.25, 0.5, 0.75 and 1 g/mouse, i.c.v.) before morphine, and during morphine-sensitization, decreased and increased the amnesia induced by pre-training morphine respectively. Three daily injections of quinpirole (0.3, 1 and 3 g/mouse, i.c.v.) or sulpiride (0.03, 0.1, 0.3 and 1 g/mouse, i.c.v.) before morphine, also decreased and increased the amnesia induced by pre-training morphine respectively. Morphine-sensitized mice received similar injections of cholinergic agents. Three daily injections of physostigmine (1, 3 and 5 g/mouse, i.c.v.) or atropine (1, 4 and 7 g/mouse, i.c.v.) before morphine, and during morphine-sensitization, decreased and increased the amnesia induced by pre-training morphine respectively. Three daily injections of nicotine (0.75, 1 and 2 g/mouse, i.c.v.) or mecamylamine (1, 3 and 6 g/mouse, i.c.v.) before morphine, also decreased and increased the amnesia induced by pre-training morphine respectively. The results suggest that morphine sensitization affects the impairment of memory formation and thus it is postulated that central dopaminergic and cholinergic systems may play an important role in this effect.
Zarrindast
Mohammad-Reza
MR
Department of Pharmacology, Tehran University of Medical Sciences, Tehran, Iran. zarinmr@ams.ac.ir
Farahmandfar
Maryam
M
Rostami
Parvin
P
Rezayof
Ameneh
A
D000647:Amnesia / Q000139:chemically induced* / Q000523:psychology*; D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D018678:Cholinergic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D015259:Dopamine Agents / Q000008:administration & dosage / Q000494:pharmacology*; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D009020:Morphine / Q000494:pharmacology*; D018721:Muscarinic Agonists / Q000494:pharmacology; D018727:Muscarinic Antagonists / Q000494:pharmacology; D018722:Nicotinic Agonists / Q000494:pharmacology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D017447:Receptors, Dopamine D1 / Q000187:drug effects; D017448:Receptors, Dopamine D2 / Q000187:drug effects; D011976:Receptors, Muscarinic / Q000187:drug effects
D000701:Analgesics, Opioid; D018678:Cholinergic Agents; D015259:Dopamine Agents; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D018721:Muscarinic Agonists; D018727:Muscarinic Antagonists; D018722:Nicotinic Agonists; D018733:Nicotinic Antagonists; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D011976:Receptors, Muscarinic; D009020:Morphine