Reciprocal opioid-opioid interactions between the ventral tegmental area and nucleus accumbens regions in mediating mu agonist-induced feeding in rats.
Feeding elicited by the mu-selective agonist, [D-Ala2, M-Phe4, Gly-ol5]-encephalin administered into the nucleus accumbens is blocked by accumbal pre-treatment with mu, delta1, delta2 and kappa, but not mu1 opioid antagonists. Correspondingly, mu-agonist-induced feeding elicited from the ventral tegmental area is blocked by ventral tegmental area pre-treatment with mu and kappa, but not delta opioid antagonists. A bi-directional opioid-opioid feeding interaction has been firmly established such that mu-agonist-induced feeding elicited from the ventral tegmental area is blocked by accumbal naltrexone, and that accumbal mu-agonist-induced feeding is blocked by naltrexone pre-treatment in the ventral tegmental area. To determine which opioid receptor subtypes mediate the regional bi-directional opioid-opioid feeding interactions between these two sites, the present study examined the dose-dependent ability of either general (naltrexone), mu (beta-funaltrexamine), kappa (nor-binaltorphamine) or delta (naltrindole) opioid antagonists administered into one site to block mu-agonist-induced feeding elicited from the other site. General, mu and kappa, but not delta opioid receptor antagonist pre-treatment in the ventral tegmental area dose-dependently reduced mu-agonist-induced feeding elicited from the nucleus accumbens. General, mu and delta, and to a lesser degree kappa, opioid receptor antagonist pre-treatment in the nucleus accumbens dose-dependently reduced mu-agonist-induced feeding elicited from the ventral tegmental area. Thus, multiple, but different opioid receptor subtypes are involved in mediating opioid-opioid feeding interactions between the nucleus accumbens and ventral tegmental area regions.
Bodnar
Richard J
RJ
Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, 65-30 Kissena Blvd., Flushing, NY 11367, USA. richard_bodnar@qc.edu
Lamonte
Nicole
N
Israel
Yuriy
Y
Kandov
Yakov
Y
Ackerman
Tsippa F
TF
Khaimova
Eleonora
E
D000595:Amino Acid Sequence; D000701:Analgesics, Opioid / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)- / Q000008:administration & dosage / Q000494:pharmacology*; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008845:Microinjections; D009714:Nucleus Accumbens / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017450:Receptors, Opioid, mu / Q000819:agonists*; D017557:Ventral Tegmental Area / Q000187:drug effects / Q000502:physiology*
D000701:Analgesics, Opioid; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-