Noradrenergic receptor blockade of the NTS attenuates the mnemonic effects of epinephrine in an appetitive light-dark discrimination learning task.
These experiments examined the contribution of noradrenergic neurons in the nucleus of the solitary tract (NTS) in mediating the memory-facilitating effects of epinephrine. In Experiment 1, saline or 0.05 or 0.1 mg/kg of epinephrine was given intraperitoneally (ip) to rats after the second day of training in a light-dark Y-maze discrimination task. On a 20-trial retention test given 2 and 7 days later, the 0.1 mg/kg epinephrine group made significantly more correct responses than controls and required fewer trials to reach criterion. In Experiment 2, phosphate-buffered saline or the noradrenergic antagonist dl-propranolol (0.3 or 1.0 microg/0.5 microl) was infused into the NTS prior to an ip injection of saline or 0.1 mg/kg of epinephrine. The memory-enhancing effects of epinephrine were attenuated by the infusion of 0.3 microg/0.5 microl of dl-propranolol into the NTS. These findings indicate an involvement of NTS noradrenergic neurons in mediating the effects of peripheral epinephrine on memory storage processes.
Clayton
E C
EC
Department of Psychology, University of Virginia, Charlottesville, Virginia 22903, USA.
Williams
C L
CL
D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects*; D001522:Behavior, Animal / Q000187:drug effects; D004193:Discrimination Learning / Q000187:drug effects*; D004837:Epinephrine / Q000494:pharmacology*; D008027:Light; D008297:Male; D008568:Memory / Q000187:drug effects*; D009474:Neurons / Q000378:metabolism; D009638:Norepinephrine / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011955:Receptors, Drug / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D017552:Solitary Nucleus / Q000187:drug effects* / Q000378:metabolism*
D011955:Receptors, Drug; D009638:Norepinephrine; D004837:Epinephrine