Effect of Agouti-related protein on development of conditioned taste aversion and oxytocin neuronal activation.
Agouti-related protein (Agrp) is an orexigenic peptide that acts as an antagonist of the melanocortin-3 and -4 receptors. Initial studies suggest similarities between the effects of Agrp and opioid peptides on ingestive behavior. Given these observations, we examined whether Agrp, similarly to opioids, alleviates conditioned taste aversion (CTA) generated by peripheral injection of LiCl. Agrp (1 nmol) delivered to the lateral cerebral ventricle, a dose known to cause orexigenic effects, was shown to partially block acquisition of LiCl-induced CTA. Agrp also decreased the percentage of c-Fos-positive oxytocin neurons induced by LiCl in the hypothalamic paraventricular and supraoptic nuclei. Inhibitory effects of Agrp on acquisition of CTA and aversion-associated activation of oxytocin neurons parallel what has previously been shown with opioid receptor agonists.
Wirth
Michelle M
MM
Research Service 151, Veterans Affairs Medical Center, 1 Veterans Drive, Minneapolis, MN 55417, USA.
Olszewski
Pawel K
PK
Levine
Allen S
AS
Giraudo
Silvia Q
SQ
D054366:Agouti Signaling Protein; D054369:Agouti-Related Protein; D000818:Animals; D018692:Antimanic Agents / Q000494:pharmacology; D001362:Avoidance Learning / Q000187:drug effects*; D003213:Conditioning, Psychological / Q000187:drug effects; D007032:Hypothalamus, Anterior / Q000166:cytology; D007276:Injections, Intraventricular; D036341:Intercellular Signaling Peptides and Proteins; D018021:Lithium Chloride / Q000494:pharmacology; D008297:Male; D009474:Neurons / Q000737:chemistry* / Q000187:drug effects*; D010121:Oxytocin / Q000032:analysis*; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology; D011506:Proteins / Q000494:pharmacology*; D016760:Proto-Oncogene Proteins c-fos / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013649:Taste
C515197:AGRP protein, rat; D054366:Agouti Signaling Protein; D054369:Agouti-Related Protein; D018692:Antimanic Agents; D036341:Intercellular Signaling Peptides and Proteins; D011506:Proteins; D016760:Proto-Oncogene Proteins c-fos; D010121:Oxytocin; D018021:Lithium Chloride