N-Allylnormetazocine (SKF-10,047): The induction of feeding by a putative sigma agonist

Several distinct classes of opiate receptors have been postulated. It has been suggested that two of these, the kappa and sigma, may play a role in the initiation of feeding. The putative sigma receptor agonist N-allylnormetazocine increased food intake at doses of 0.1 and 1 mg/kg, whereas higher doses caused a decreased intake under some conditions. This stimulatory effect increased after repeated injections and was naloxone reversible. After repeated injections of N-allylnormetzocine, the feeding response to ketocyclazocine, but not morphine, appeared at an earlier point than in naive rats. These experiments support the suggestion that the sigma receptor may play some role in the initiation of feeding.