The effect of peripheral noradrenaline depletion on responding on a schedule of differential reinforcement of low rates of response (DRL).
First, it was confirmed that systemic injection of the neurotoxin 6-hydroxydopamine HBr (30 mg/kg IP) depleted noradrenaline levels in rat heart, but not centrally. Losses averaged 90% of control 1 day after injection, and 50% at 42 days. The same drug and dose was then administered to 50% of a group of rats which had been trained to lever-press for food reward on continuous reinforcement (CRF). After further CRF sessions, the rats were changed to a schedule of Differential Reinforcement of Low Rates of Response with a 20-s criterion (DRL 20). The drugged rats earned fewer reinforcements during DRL than did controls, and made fewer responses. Temporal discrimination (shown by the IRT/Opp distribution) was disrupted. It is concluded that peripheral noradrenergic systems may be involved in the control over responding by temporal cues associated with reward and non-reward.
D000704:Analysis of Variance; D000818:Animals; D003216:Conditioning, Operant / Q000187:drug effects*; D006892:Hydroxydopamines / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000502:physiology*; D016627:Oxidopamine; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012055:Reinforcement Schedule
D006892:Hydroxydopamines; D016627:Oxidopamine; D011433:Propranolol; D009638:Norepinephrine