Effect of Carbohydrate Type on Brain Composition and Senescence in Aging, Hyperinsulinemia-prone OBESE LA/Ntul//-cp Rats

To determine if phenotype and the carbohydrate type resulted in alterations in brain composition in the obese phenotype of the congenic LA/Ntul//-cp rat, groups (n= 8 rats/group) of male littermate lean and obese rats were fed standardized isocaloric diets containing 54% (w/w) cornstarch (ST diet) or 54% (w/w) sucrose (SUC diet) from 1 until 10.5 ± 0.5 months of age. The obese phenotype of his strain develops early onset chronic hyperinsulinemia without NIDDM associated with hypertrophic-hyperplastic obesity during early postweaning growth. Brain tissues were dissected, and representative aliquots subjected to total fat, protein, and DNA analysis. Body weights of obese >> lean and were greater when fed the SUC than the ST diet in both phenotypes. Brain mass of lean > obese, and diet was associated with modestly lower brain weights in rats fed the SUC than the ST diet. Brain total Protein and DNA content of lean rats were > obese rats and were modestly Lower in SUC than ST fed rats in both phenotypes, but the percent of lipid content was proportional to brain mass. Total body fat mass of obese was significantly greater than occurred in lean littermates and was only modestly greater in SUC than ST fed rats in both phenotypes. These results indicate that brain growth and cellular development is impaired in the aging, hyperinsulinemia-prone obese phenotype of this strain, were further impaired when fed SUC than ST diets, and the decreased brain parameters were likely associated with development of a chronic neuronal inflammatory syndrome common to excessive fat accretion and obesity, resulting in premature brain senescence.