Responses to dietary adulterations in rats with zona incerta lesions.

Large lesions of the rostral zona incerta (ZI) permanently reduced food and water intake and body weight to about 75% of control levels. When quinine hydrochloride was added to the water supply, the experimental animals exhibited a somewhat greater initial decrease in fluid consumption, but otherwise responded much like control rats to quinine adulteration of both food and water. The ZI animals reduced their fluid intake when water was added to the food supply, in the form of wet mash, while the controls showed no compensation for the auxiliary water. When presented with sucrose solutions, the ZI animals increased their fluid intake, but reduced their mash consumption, to a greater degree than control rats. The experimental animals also showed an exaggerated response in both food and caloric intake to the addition of sucrose to the wet mash.