ß-Funaltrexamine (ß-FNA) decreases deprivation and opioid-induced feeding

We studied the effect of the μ antagonist, ß-funaltrexamine (ß-FNA) on deprivation and opioid-induced feeding. Intracerebroventricular pre-treatment of 20 h deprived rats with 0.1, 1, 10 and 20 nmol of ß-FNA decreased feeding by 24%, 50%, 50% and 38% during the first hour. Central administration of ß-FNA (0.1, 1 and 10 nmol) also decreased feeding induced by the μ opioid agonist, DAMGO by 57%, 60% and 71%. Feeding induced by the δ agonist, DSLET, was decreased by pre-treatment with ß-FNA; but only during the 1-2 h time points, a time when relatively little food was ingested. Intraventricular injection of ß-FNA failed to alter feeding stimulated by the κ opioid agonist, U-50,488H. These data further substantiate a role for the opioid receptor in deprivation and opioid-induced feeding.