VENTRAL TEGMENTAL INJECTIONS OF MORPHINE BUT NOT U-50,488H ENHANCE FEEDING IN FOOD-DEPRIVED RATS

Food-deprived rats received microinjections of the preferential mu opi ate morphine or the selective kappa opiate U-50,488H (0.1, 1 and 10 nm ol) into the ventral tegmental area (VTA). Meals were divided into dis crete segments so that repeated measures of the speed of eating and th e latency to initiate eating could be obtained. Morphine produced a do se-dependant increase in the speed of eating. Injections of saline or U-50,488H into the VTA or injections of morphine dorsal to the VTA wer e ineffective. Neither morphine nor U-50,488H had a significant effect on the latency to initiate feeding. These data suggest that CL but no t K opioid receptors in the VTA are involved in the regulation of feed ing in food-deprived rats.