Reactivity of normal and VMH-lesion rats to quinine-adulterated foods: negative evidence for negative finickiness.

Much of the evidence for the existence of a negative finickiness component in the ventromedial hypothalamic (VMH) syndrome comes from studies comparing the relative reactivities of VMH and normal rats to quinine adulteration. The present experiments addressed two major questions regarding the response of normal and VMH animals to quinine: (a) Do the anorexic properties of quinine depend on quinine's sensory properties (i.e., its bitter taste) or on its postingestive effects; (b) do VMH rats in fact overrespond to quinine adulteration? These issues were examined by comparing the feeding adjustments to quinine by VMH and normal animals in a sham-feeding situation and under normal feeding circumstances, on animals' initial exposure to this drug. The results were consistent with the view that the sensory properties of quinine alone were sufficient to induce large changes of food intake in both groups. In terms of whether lesion rats were more reactive to the taste of quinine, it is argued that previous research had measured reactivity in two dissimilar ways. The present data were used to illuminate how use of these two procedures for measuring reactivity lead to diametrically opposed conclusions regarding the existence of negative finickiness in the VMH syndrome. It is suggested that when the more appropriate measure of reactivity is adopted and when the confound of body weight differences between normal and VMH animals is eliminated, little evidence exists for a conclusion that VMH rats are more reactive than normals to quinine-adulterated foods.