Genotype dependency of adaptation in adipose tissue metabolism after short-term overfeeding

The present study investigated the interaction of genotype and short-term overfeeding on adipose tissue metabolism of six pairs of male monozygotic twins. The sedentary nonobese twins were submitted to a 22-day overfeeding period in which their normal daily intake was supplemented by an additional 1,000 kcal/day. A fat tissue biopsy was performed in the suprailiac region before and after overfeeding to determine fat cell diameter and basal and maximal stimulated epinephrine, norepinephrine, and isoproterenol lipolysis from collagenase-isolated fat cells. Fat cell basal and maximal insulin-stimulated glucose conversion into triglycerides (basal and stimulated lipogenesis) were measured using [14C]glucose. Adipose tissue heparin-releasable lipoprotein lipase activity (LPL) was also determined. A repeated measures analysis of variance revealed overfeeding induced significant elevations in basal lipogenesis (P less than 0.05) and fat cell diameter (P less than 0.05). No significant group changes were noted in basal, epinephrine-, norepinephrine-, and isoproterenol-stimulated lipolysis, insulin-stimulated lipogenesis, and LPL activity due to large individual variation in the response to overfeeding. However, significant intrapair resemblance was noted in the changes of the aforementioned variables, suggesting a coherent within-twin pair response, despite large between-pair variation in response. Less within-pair similarity was noted in changes in basal lipogenesis and fat cell diameter. The results of the present study suggest that overfeeding induced a large range of adipose tissue metabolic responses and that the genotype plays a role in determining the sensitivity of adipose tissue adaptation to caloric affluence.