Fat Intake and obesity-related parameters predict striatal BDNF gene expression and dopamine metabolite levels in cafeteria diet-fed rats

Abstract

Modern westernized diet is a major risk factor associated with the current obesity epidemic. To study the effects of dietary choices of Western societies, the cafeteria diet has been validated as a preclinical model of obesity. We aimed to investigate the behavioral and metabolic alterations induced by a cafeteria diet on gene expression and neurotransmitter contents involved in neural plasticity and reward processing. Male Wistar rats were exposed to either standard or cafeteria diet for 9 weeks. Food intake and body weight were scored daily. Behavioral effects were assessed in the elevated plus-maze (EPM) and open field (OFT) tests. Serum biochemical parameters, brain monoamines, and BDNF, TrkB, CRF, CREB, and Dnmt3A mRNA levels were analyzed in reward-related brain regions. We found that cafeteria-diet rats consumed more energy and food than the control group, leading to increased body weight gain and adiposity. The cafeteria-diet rats showed an anxiolytic-like effect in the OFT, but not in the EPM. The cafeteria diet increased BDNF expression in the dorsal striatum (DS), and norepinephrine, 5-HT, TrkB, CREB, and Dnmt3A levels in the hippocampus. Additionally, multiple regression analysis showed that accumbal DOPAC and BDNF mRNA levels were robustly predicted by hyperphagia, fat mass accumulation, and body weight gain only in the cafeteria group. Overall, cafeteria diet-induced hyperphagia could lead to alterations in hedonic and motivational control of food intake through changes in dopamine metabolism and BDNF signaling in the nucleus accumbens and the DS.