Nicotinic cholinergic system involvement in eyeblink classical conditioning in rabbits.
A nicotinic cholinergic antagonist, mecamylamine (MEC), was administered to rabbits tested on eyeblink classical conditioning (EBCC) in the 750-ms delay paradigm for 10 90-trial sessions. Nicotinic receptors were measured in 3 brain regions in 5 treatment groups: paired conditioned stimulus-unconditioned stimulus (CS-US) presentations with (a) vehicle, young; (b) vehicle, older; (c) 0.5 mg/kg MEC, young; unpaired CS-US with (d) 0.5 mg/kg MEC, young; and (e) vehicle, young. Daily MEC injections disrupted acquisition in young rabbits (769 trials to learning criterion vs. 323 trials for vehicle-treated young rabbits). MEC-treated young rabbits learned similarly to older rabbits. Brain nicotinic receptors were not affected by 10 daily MEC injections. To our knowledge, this experimental protocol, using a low MEC dose to selectively inhibit nicotinic cholinergic receptors, is the first to demonstrate a role for nicotinic cholinergic receptors in EBCC.
Woodruff-Pak
D S
DS
Department of Psychology, Temple University, Philadelphia, Pennsylvania 19122.
Li
Y T
YT
Kazmi
A
A
Kem
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WR
D000818:Animals; D001245:Association Learning / Q000187:drug effects / Q000502:physiology; D001921:Brain / Q000187:drug effects / Q000502:physiology; D001931:Brain Mapping; D003214:Conditioning, Classical / Q000187:drug effects / Q000502:physiology*; D003215:Conditioning, Eyelid / Q000187:drug effects / Q000502:physiology*; D005260:Female; D008297:Male; D008464:Mecamylamine / Q000494:pharmacology; D011939:Mental Recall / Q000187:drug effects / Q000502:physiology; D011817:Rabbits; D011950:Receptors, Cholinergic / Q000187:drug effects / Q000502:physiology*; D011978:Receptors, Nicotinic / Q000187:drug effects / Q000502:physiology*
D011950:Receptors, Cholinergic; D011978:Receptors, Nicotinic; D008464:Mecamylamine