The effects of opiate antagonists on food intake are stereospecific.

Abstract It has recently been suggested that endogenous opiate mechanisms may be significant in the physiological mechanisms controlling feeding and appetite. Consistent with this view, several studies have shown that the opiate antagonist, naloxone, will reduce food intake in experimental animals. However, it has not been shown conclusively that this effect is related to an action at opiate receptors. In the present study a wide range of doses of naloxone reduced the food intake of food-deprived rats and this effect was found to have a relatively short duration of action. Similar reductions in eating were found with two benzomorphan compounds (Mr1452 and Mr2266), known to act as opiate antagonists. However, the (+) isomers of these compounds (Mr1453 and Mr2267), which are not potent opiate antagonists, did not reduce food intake. It is concluded that food intake is reduced by the blockade of opiate recetors.