Metabolic Consequences of the Early Onset of Obesity in Common Marmoset Monkeys
1Nutrition Laboratory, Conservation Ecology Center, Smithsonian Conservation Biology Institute, National Zoological Park, Washington, DC, USA; 2Research Department, American College of Obstetricians and Gynecologists, Washington, DC, USA; 3Barshop Institute for Longevity & Aging Studies, University of Texas Health Science Center, San Antonio, TX, USA; 4Department of Neuroscience, Georgetown University, Washington DC, USA; 5Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI, USA
Abstract
We examined the patterns of fat mass gain from birth to 12 mo in common marmosets (Callithrix jacchus), and tested the hypotheses that juvenile marmosets with excess adipose tissue will display higher fasting glucose, decreased insulin sensitivity, and decreased ability to clear glucose from the blood stream. Lean and fat mass was measured by quantitative magnetic resonance at 1, 2, 6, and 12 mo for 39 marmoset infants. Circulating glucose was measured by glucometer; insulin and adiponenctin by commercial assays. The QUICKI (a measure of insulin sensitivity) was calculated for subjects with fasting glucose and insulin measures. Oral glucose tolerance tests (OGTT) were conducted at 12 mo on 35 subjects.
Results: Subjects classified as Fat (>14% body fat) at 12 mo already had higher percent body fat by 1 mo and had both greater lean mass (198.4±6.2 g vs. 174.0±6.8 g, p=0.013) and fat mass (45.5±5.0 g vs. 24.9±3.4 g, p=0.002) by 6 mo. Percent body fat decreased between 1 and 12 mo in Normal subjects; in Fat subjects it increased.1 At 6 mo Fat subjects already had significantly lower insulin sensitivity (mean QUICKI = 0.378±0.029 vs. 0.525±.019, N=11, p=0.003). At 12 mo Fat subjects had lower QICKI, higher fasting glucose (129.3±9.1 mg/dL versus 106.1±6.5 mg/dL, p=0.042) and circulating adiponectin tended to be lower (p=0.057). The OGTT results demonstrated that Fat animals had a decreased ability to clear glucose.2
Conclusions: Excess adiposity in captive marmosets develops by 1 mo. Early onset obesity in marmosets results in impaired glucose homeostasis by 1 yr.
Literature Cited
1. Power M.L., C.N. Ross, J. Schulkin, and S.D. Tardif. 2012. The development of obesity begins at an early age in captive common marmosets (Callithrix jacchus). Am J Primatol 74:261–269.
2. Power M.L., C.N. Ross, J. Schulkin, T.Z. Ziegler, and S.D. Tardif. Metabolic consequences of the early onset of obesity in common marmoset monkeys. Obesity (in press).