Chronic food restriction produces a variety of physiological and behavioral adaptations including a potentiation of the reinforcing effect of food, drugs and lateral hypothalamic electrical stimulation. Previous work in this laboratory has revealed that the lowering of self-stimulation threshold by food restriction is reduced by mu- and kappa-selective opioid antagonists. In the present study, the effect of chronic food restriction on levels of three prodynorphin-derived peptides, namely dynorphin A(1-17) (A(1-17)), dynorphin A(1-8) A(1-8) and dynorphin B-1-13 (B-1-13) were measured in eleven brain regions known to be involved in appetite, taste and reward. Food restriction increased levels of A(1-17) in dorsal medial (+19.6%), ventral medial (+24.2%) and medial preoptic (+82.9%) hypothalamic areas. Levels of A(1-17) decreased in the central nucleus of the amygdala (-35.1%). Food restriction increased levels of A(1-8) in nucleus accumbens (+34.4%), bed nucleus of the stria terminalis (+24.5%) and lateral hypothalamus (+41.9%). Food restriction had no effect on levels of B-1-13. A(1-17) is highly kappa-preferring and the brain regions in which levels increased all have a high ratio of kappa:mu and delta receptors. A(1-8) is less discriminating among opioid receptor types and the brain regions in which levels increased have a low ratio of kappa:mu and delta receptors. The present results suggest that food restriction alters posttranslational processing within the dynorphin A domain of the prodynorphin precursor, possibly leading to a change in the balance between kappa and non-kappa opioid receptor stimulation in specific brain regions.