A nicotinic cholinergic agonist (GTS-21) and eyeblink classical conditioning: Acquisition, retention, and relearning in older rabbits

Previously we demonstrated that GTS-21, a nicotinic cholinergic agonist, am eliorated eyeblink classical conditioning deficits in older rabbits. The pr esent experiment was under taken to replicate and extend these results by e xamining the effects of GTS-21 on retention and relearning. Retired breeder rabbits received 15 daily injections of 0.5 mg/kg GTS 21 (n = 8) or steril e saline vehicle (n = 8) during acquisition training, and no further inject ions occurred. Acquisition of conditioned responses (CRs) was significantly better in GTS-21-treated rabbits. During the first tone-alone retention se ssion in week 6 of the experiment, rabbits initially treated with GTS-21 pr oduced significantly more CRs than vehicle-treated rabbits. There were no g roup differences in retention at the 13-week retest. Differences in relearn ing were in the predicted direction but did not attain statistical signific ance. Results indicate that treatment with GTS-21 ameliorates learning beyo nd the period when the drug is actually administered.