Metabotropic Glutamate Receptors 7 within the Nucleus Accumbens are Involved in Relief Learning in Rats.
Relief learning is an appetitive association of a formally neutral cue with relief induced by the offset of an aversive stimulus. Since the nucleus accumbens mediates relief learning and accumbal metabotropic glutamate receptors 7 (mGluR7) modulate appetitive-like processes, we hypothesized that accumbal mGluR7 may be involved in the modulation of relief learning. Therefore, we injected the allosteric mGluR7 agonist AMN082 into the nucleus accumbens and tested the effects of these injections on acquisition and expression of relief memory, as well as on the reactivity to electric stimuli. AMN082 injections blocked acquisition but not expression of relief memory. In addition, accumbal AMN082 injections strongly reduced the locomotor reactivity to electric stimuli indicating antinociceptive effects. These antinociceptive effects might be causal for the blockade of relief learning after AMN082 injections. Taken together, the present study indicates that functional activation of accumbal mGluR7 has antinociceptive effects that interfere with relief learning.
Evelyn
E
Kahl
Institute for Pharmacology and Toxicology, Leipziger Straße 44, D-39120 Magdeburg, Germany. markus.fendt@med.ovgu.de.
Markus
M
Fendt
D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects / Q000502:physiology*; D001245:Association Learning / Q000187:drug effects / Q000502:physiology*; D001559:Benzhydryl Compounds / Q000494:pharmacology; D002408:Catheters, Indwelling; D004558:Electric Stimulation; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology*; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D009483:Neuropsychological Tests; D059226:Nociceptive Pain / Q000188:drug therapy / Q000378:metabolism*; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism*; D017207:Rats, Sprague-Dawley; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists / Q000378:metabolism*; D013216:Reflex, Startle / Q000187:drug effects / Q000502:physiology
D001559:Benzhydryl Compounds; D018690:Excitatory Amino Acid Agonists; C507346:N,N'-dibenzhydrylethane-1,2-diamine dihydrochloride; D018094:Receptors, Metabotropic Glutamate; C102719:metabotropic glutamate receptor 7