The role of nicotinic receptors in the amelioration of cholinesterase inhibitors in scopolamine-induced memory deficits.
BACKGROUND
Nicotine receptors in the brain are closely related with memory amelioration induced by cholinesterase inhibitors.


OBJECTIVE
The present study was undertaken to clarify the role of nicotinic receptors in the ameliorative effects of cholinesterase inhibitors on scopolamine-induced memory deficit.


METHODS
Drug effects were measured using an eight-arm radial maze with four arms baited. Hippocampal theta rhythm during the radial maze task was also recorded with a polygraph system using a telemetric technique.


RESULTS
Scopolamine (0.5 mg/kg, i.p.) caused a spatial memory deficit as well as an increase in hippocampal theta power during radial maze performance. Pilocarpine, nicotine, physostigmine, and donepezil antagonized the effects of scopolamine. The ameliorative effects of nicotine, physostigmine, and donepezil but not piocarpine on memory performance and hippocampal theta activity were reversed by mecamylamine.


CONCLUSIONS
These results indicate that nicotinic receptors have an essential role in the ameliorative effects of cholinesterase inhibitors in both scopolamine-induced memory deficit and the increase in hippocampal theta activity.
Masuoka
Takayoshi
T
Department of Medicinal Pharmacology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, 700-8530, Japan.
Kamei
Chiaki
C
D000818:Animals; D002800:Cholinesterase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D004195:Disease Models, Animal; D000077265:Donepezil; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D006624:Hippocampus / Q000187:drug effects / Q000503:physiopathology; D007189:Indans / Q000494:pharmacology / Q000627:therapeutic use; D007859:Learning Disabilities / Q000139:chemically induced* / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D008464:Mecamylamine / Q000494:pharmacology; D018721:Muscarinic Agonists / Q000494:pharmacology; D009538:Nicotine / Q000494:pharmacology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D010830:Physostigmine / Q000494:pharmacology / Q000627:therapeutic use; D010862:Pilocarpine / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology / Q000627:therapeutic use; D051381:Rats; D017208:Rats, Wistar; D011978:Receptors, Nicotinic / Q000502:physiology*; D012601:Scopolamine; D013826:Theta Rhythm / Q000187:drug effects
D002800:Cholinesterase Inhibitors; D007189:Indans; D018721:Muscarinic Agonists; D018733:Nicotinic Antagonists; D010880:Piperidines; D011978:Receptors, Nicotinic; D010862:Pilocarpine; D008464:Mecamylamine; D009538:Nicotine; D000077265:Donepezil; D010830:Physostigmine; D012601:Scopolamine