2016 Theses Doctoral

Early intervention in a mouse model of childhood obesity: effects on brown adipose tissue function

Lerea, Jaclyn Sadie

Due to the high childhood obesity rates within the United States, it is necessary to develop efficacious strategies to combat childhood obesity. To explore whether early intervention can produce lasting metabolic improvements, we used a mouse model of genetically-induced hypothalamic leptin resistance (LeprNkx2.1knockout, hereby known as KO) that exhibits early-onset hyperphagia and obesity. We found that KO mice exhibit reduced capacity of the brown adipose tissue (as seen by disorganized mitochondrial structure). Brown adipose tissue capacity can be restored by paired-feeding in the peri-weaning period, leading to persistent improvements in later adiposity even after restriction ends. These studies lead us to investigate the maturation process of brown adipose tissue in the peri-weaning period. We found that brown adipose tissue expansion between 2 to 3 weeks of age is accompanied by a reduced thermogenic capacity in control mice, as determined by protein levels of uncoupling protein 1 and disorganization of the mitochondrial cristae. Thermogenic function was restored by 5 weeks of age, as demonstrated by a peak of uncoupling protein 1, in control mice but not KO mice. Paired-feeding of KO mice in the peri-weaning period rescued this peak at 5 weeks of age. These studies elucidate a critical period when brown adipose tissue expansion is followed by activation. The magnitude of brown adipose tissue activation at this time might be predictive of future obesity and metabolic rate, highlighting a potential therapeutic time window in which to intervene in pediatric obesity.