Effects of propranolol on, and noradrenergic correlates of, the response to nonreward.
Rats were rewarded by food for running in a straight runway with short (15 sec) intertrial intervals. On the final day, animals were subjected to either 14 extinction trials or 14 rewarded trials. During acquisition, half of each group had been injected once daily for 15 days with propranolol (5 mg/kg IP), the remainder with saline vehicle. All animals were killed immediately after the final trial and the cerebral cortex taken for noradrenaline assay and radioligand binding to beta- and alpha 2-adrenoceptors. Propranolol increased running times early in extinction; this effect was replicated in a second experiment. Neither the drug injections nor the extinction procedure affected neurochemical measures. However, the rate of extinction correlated positively with both beta- and alpha 2-adrenoceptor number. Although consistent with the theory that beta-adrenoceptors are involved in adaptation to stress, these results differ from our previous findings. The relationship between beta-adrenoceptor number and the response to stress may depend on the severity of the stress.
Marsland
A L
AL
Department of Psychology, University College London, UK.
Salmon
P
P
Terry
P
P
Stanford
S C
SC
D000818:Animals; D003216:Conditioning, Operant / Q000187:drug effects; D005108:Extinction, Psychological / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009638:Norepinephrine / Q000378:metabolism* / Q000502:physiology; D011433:Propranolol / Q000494:pharmacology*; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D012201:Reward
D011433:Propranolol; D009638:Norepinephrine