Suppressive effects of naloxone on food and water intake in vagotomized rats.

Rats were (1) sham operated and ad lib fed, (2) given bilateral subdiaphragmatic vagotomies or (3) sham operated and pair fed to the vagotomized group. At the start of the dark period, following a 24 hr fast, the animals were tested for the ability of naloxone (0.5, 1.5, 3.0 and 5.0 mg/kg body weight) to suppress food and water consumption. In comparison to saline control injections the data indicated that naloxone was equally effective in suppressing food intake, over a two hour period, in all groups. Similarly naloxone effectively decreased water consumption of all groups in comparison to their saline trials. When the post naloxone data were calculated as a percentage of saline baseline this suppression was, at times, slightly greater in the vagotomized group than in the other groups. However, this may be an artifact of the low baseline intake of the vagotomized group. The results are discussed with relevance to the recent findings of others concerning this subject.