Increased Brown Adipose Tissue Mediates Healthful Aging as Reflected by Enhanced Exercise Performance and Protection Against Glucose Intolerance

Abstract

Increased brown adipose tissue results in improved metabolism and protection against cold exposure in humans. The goal of this investigation was to determine if increased brown adipose tissue can improve exercise performance and protect against glucose intolerance. This was accomplished by surgical removal of interscapular brown adipose tissue from c57 wild type mice and transplanting it to other c57 wild type mice. Following transplantation it was necessary to determine how long it would take for any changes to develop. 3 days following transplantation both recipients and donors were exercise tested using a treadmill. No differences were observed between recipients and donors in terms of both running distance (372 ± 14m vs. 377 ± 12m) and work to exhaustion (17.7 ± 1.0 J vs. 16.5 ± 1.4 J). However, at 8 weeks following brown adipose tissue transplantation, the recipient mice demonstrated enhanced exercise performance, p<0.05, in terms of running distance (507 ± 16m) and work to exhaustion (24.3 ± 1.4J), whereas exercise capacity did not change in brown adipose tissue donors. Indirect calorimetry was measured during exercise, with recipients exhibiting improved metabolism, p<0.05, resulting in 7% higher levels of peak oxygen consumption (VO2), 15% higher levels of peak carbon dioxide production (VCO2), and 9% higher levels of peak energy expenditure (EE). The improved exercise metabolism observed in the c57 recipients was accompanied by improved glucose tolerance. Following 8 weeks after brown adipose tissue transplantation, c57 recipients exhibited improved glucose tolerance as demonstrated by glucose tolerance test. Glucose (1g/kg), was administered IP and measurements of blood glucose were made at 30 minute intervals until blood glucose returned to baseline. Glucose tolerance was measured as the area under the curve, which was lower, p<0.05, in brown adipose tissue recipients (7515 ± 676 A.U.) as compared to c57 donors (11051 ± 1035 A.U.). Therefore, increased brown adipose tissue induces healthful aging, both in terms of enhanced exercise performance and improved metabolism resulting in protection against diabetes.