Short-Term Consumption of a Low Protein Diet May Decrease Anxiety in Adult Female Rats.

Abstract

Exploratory behavior is crucial to the survival of most animals, allowing for the evaluation of environmental conditions and foraging behaviors. Dietary manipulations change the emotional reactivity of rats; specifically, diets low in protein or high in fat increase exploratory behavior and activity, suggestive of lower anxiety (Almeida et al., 1996; Prasad & Prasad, 1996). The elevated plus maze (EPM) has proven to be a valid index of fear, with less anxious subjects spending more time and activity on open arms. In previous dietary/behavioral studies, manipulations have been conducted during early critical stages of development, resulting in distinct neurophysiological and neurochemical alterations responsible for exhibited behaviors. This study explores whether strictly postnatal protein deprivation reduces anxiety. Behavior patterns of adult rats on the EPM will be used to assess activity, exploration, and anxiety. On Day 1, fear of novelty is critical to plus-maze performance, whereas fear of heights or predation is important thereafter (File, 1993). The effect of diet shouldn't be apparent within the first two test days; rather, the diet manipulation should affect the rats' secondary form of fear, in the recovery phase. Adult female rats consumed either a standard lab chow or a low-protein/high-fat diet for 15 days before six days of testing. If low-protein consumption reduces anxiety, the Low Protein rats should spend a higher percentage of time on open arms during the recovery phase (Days 3-6). Preliminary results of differences in means and graphical data suggest that protein deficient rats exhibit less fear and increased impulsiveness.