The effects of beta-noradrenergic receptor blockade on acquisition of eyeblink conditioning in 3-month-old F344 rats.
There is evidence that blocking beta-noradrenergic receptors will cause deficits in some forms of learning. We investigated the effects of systemic injections of 1, 5, and 10 mg/kg doses of propranolol on acquisition of delay eyeblink conditioning in 3-month-old Fischer 344 rats. We presented a 3-kHz, 90-dB tone as a conditioning stimulus and a 6 psi airpuff as our unconditioned stimulus to freely moving rats. We monitored eyelid activity using EMG signals. The treatment subjects were injected with either propranolol or saline 0.5 h prior to daily training sessions. Two groups of control subjects, one receiving injections of saline and one receiving injections of 5 mg/kg propranolol, received daily training sessions with unpaired and randomized presentation of the tone and airpuff. Each daily training session for the treatment groups consisted of 27 paired training trials and 3 conditioned stimulus-alone training trials. Rats injected with saline vehicle or with 1 mg/kg propranolol achieved a 60% or better learned response rate within two training sessions. Rats injected with 5 or 10 mg/kg propranolol never achieved a response rate significantly different from animals that received unpaired, random presentations of the tone and airpuff stimuli. These results agree with prior studies from our lab that have shown a dose-dependent effect of beta-noradrenergic receptor blockade on learning in rabbit eyeblink conditioning as well as in a runway, motor learning paradigm. We believe that the beta-noradrenergic system plays an important role in learning and memory in more than one cerebellar-dependent learning paradigm.
Cartford
M Claire
MC
Center for Aging and Brain Repair, Department of Neurosurgery, University of South Florida, College of Medicine, Tampa, USA. mcartfor@hsc.usf.edu
Allgeier
Chrissy A
CA
Bickford
Paula C
PC
D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001767:Blinking / Q000187:drug effects*; D003213:Conditioning, Psychological / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004576:Electromyography; D007858:Learning / Q000187:drug effects; D008297:Male; D008568:Memory / Q000187:drug effects; D011433:Propranolol / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011916:Rats, Inbred F344; D011941:Receptors, Adrenergic / Q000187:drug effects*; D013997:Time Factors
D000319:Adrenergic beta-Antagonists; D011941:Receptors, Adrenergic; D011433:Propranolol