BRAIN DERIVED NEUROTROPHIC FACTOR CHANGES IN RESPONSE TO SUCROSE INTAKE IN ADOLESCENT RATS

Abstract

Sugar intake is a natural stimulus, like sodium or stress, and activates similar neural circuits involved in mediating reward. Sugar intake may lead to a sensitization of the reward system, changing the response to subsequent rewarding experiences. BDNF plays an important role in the survival, maintenance and growth of many types of neurons and is expressed abundantly in the nucleus accumbens (NAcc) and prefrontal cortex (PFC). Rodents maintained on energy‐rich diets containing high levels of sugar show impaired learning and memory performance, and recent evidence indicates that such deficits may be related to the effects of these diets on the regulation of brain‐derived neurotrophic factor (BDNF) in the brain. Nevertheless, it is not clear how sucrose intake translates into decreased BDNF levels in brain reward areas. The specific aim of this study, therefore, addresses the lack of information on the role of sugar intake, as a natural reward, in BDNF expression in the PFC and NAcc.HypothesisAnimals pre‐exposed to sucrose intake in early adolescence are more likely to maintain elevated levels of sucrose intake which is related to changes in BDNF levels in PFC and NAcc.Methods1) We have determined preferred sucrose concentration in adolescent rats using a chronic intermittent sucrose intake model. 2)We have determined if early sucrose intake affects adult sucrose intake and examined changes in BDNF levels of expression in the PFC and NAcc. On PND28, (pre‐adolescents period) rats were assigned to sucrose (5% or 15%) or tap water groups. From PND28 (adolescent period) to PND32 rats had 2hr access to sucrose or water each day. After 8 weeks, rats were re‐exposed to sucrose or water and after the last sucrose intake session, animals were sacrificed. Brains were extracted and prepared for immunoassay analysis (ELISA) for identifying Pro and Mature BDNF levels.ResultsAdolescent rats showed significantly higher levels of sucrose intake at the 5% concentration than the 15% concentration. Both ProBDNF levels and Mature BDNF levels in the PFC showed statistically significant differences among the groups, whereas there is not any statistically significant change among groups in NAcc.ConclusionOur study demonstrated for the first time that sucrose ingestion affects BDNF levels in PFC but not in NAcc in the brain when adolescent rats are pre‐exposed to sucrose intake.Support or Funding InformationOklahoma State University Vice President office of research 2019