ASSOCIATION BETWEEN THE AMYGDALA AND NUCLEUS OF THE SOLITARY TRACT INMU-OPIOID INDUCED FEEDING IN THE RAT

The central nucleus of the amygdala (CNA) and the nucleus of the solit ary tract (NTS) are important in the regulation of ingestive behavior. We evaluated whether opioid-opioid signaling between the CNA and rost ral NTS (rNTS) affect feeding behavior. To test this, rats were doubly cannulated with one cannula placed in the rNTS and one cannula in the CNA, allowing for co-administration of an opioid agonist into one sit e and an opioid antagonist into the other. Tyr-D-Ala-Gly-(me) Phe-Gly- ol (DAMGO) (2 nmol) injected into the CNA (CNA DAMGO) increased feedin g more than two-fold compared to the vehicle-injected rats. This incre ase in food intake was blocked when doses of 26.5 and 79 nmol of naltr exone (NTX) were injected into the rNTS. In the reverse situation, rNT S DAMGO increased food intake above control levels, and CNA NTX blocke d DAMGO-induced feeding when administrated in doses of 26.5 and 79 nmo l. This suggests that a bi-directional opioid-opioid signaling pathway exists between the CNA and the rNTS which influences feeding via mu-o pioid receptors. (C) 1998 Elsevier Science B.V. All rights reserved.