Sympathoadrenal effects on extinction of rewarded running in the rat.
Two groups of rats underwent adrenal demedullation or sham surgery before being trained to run in a straight runaway for food reward at a short intertrial interval (90 s). Half of each group of animals were then injected IP with the sympathetic neurotoxin, 6-hydroxydopamine HBr (6-OHDA; 30 mg/kg); the remainder received saline vehicle. After 3 more days of acquisition training, running was extinguished over 12 trials in all rats. Running times were similar in all groups at the start of extinction. In saline-injected animals, extinction proceeded more slowly in the demedullated than in the sham-operated group, but this effect was largely abolished by 6-OHDA. Consistent with previous results, there was evidence that 6-OHDA facilitated extinction, irrespective of adrenal demedullation, but this effect was most apparent in the time taken to emerge from the start-box. The rats were killed two days after the end of the experiment; cardiac noradrenaline levels were depleted by 83% of control values in 6-OHDA-treated animals. The results suggest that the adrenal medulla and sympathetic neurones have opposing and interacting effects on the response to nonreward.
Terry
P
P
Department of Psychology, University College London, UK.
Stanford
S C
SC
Salmon
P
P
D000311:Adrenal Glands / Q000294:innervation*; D000313:Adrenal Medulla / Q000294:innervation; D000818:Animals; D001070:Appetitive Behavior / Q000502:physiology*; D001143:Arousal / Q000502:physiology*; D005108:Extinction, Psychological / Q000502:physiology*; D006321:Heart / Q000294:innervation; D008297:Male; D009042:Motivation; D009206:Myocardium / Q000378:metabolism; D009638:Norepinephrine / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D013564:Sympathetic Nervous System / Q000502:physiology*
D009638:Norepinephrine