Untitled Document

Research

Joseph W. Kemnitz

Ph.D., University of Wisconsin-Madison
Professor, Department of Physiology, Interdepartmental Graduate Program in Nutritional Sciences
Director, Primate Research Center
kemnitz@primate.wisc.edu

Regulation of Energy Balance and the Processes of Aging

My laboratory studies the mechanisms that regulate food intake and energy expenditure and the consequences of caloric imbalances for health and risk of disease. Most of our projects utilize nonhuman primates, especially rhesus monkeys, because these animals share so many important characteristics with our own species.

Recent efforts have focused on changes that occur in middle and late life. Rhesus monkeys achieve adult body size by approximately eight years of age and can live as long as 40 years. Males are, on average, 25% heavier than females during adulthood. During middle age, monkeys of both sexes tend to add body fat and lose lean body mass, and some middle-aged monkeys develop marked obesity. Obese monkeys provide a good model for studying certain complications of human obesity. For example, there are similar abnormalities in glucose and lipid metabolism, blood pressure and hormone levels in the obese animals. Obese monkeys have elevated insulin levels and often impaired glucose tolerance. Their ability to maintain normal blood glucose levels declines as they get older, and some obese monkeys become diabetic in later life.

The effect of restricted food intake on aging is being assessed prospectively in a multidisciplinary study of rhesus monkeys. Half of the animals are being fed a moderately reduced amount of a nutritious diet, while the control monkeys are allowed to eat ad libitum. It is hypothesized that the food-restricted group will exhibit slower rates of change in certain characteristics of aging, including blood glucose regulation. Indeed, after ten years of study the restricted monkeys have greater insulin sensitivity, lower glucose concentrations and improved glucose tolerance. Their metabolism of energy is also affected. Such effects of reduced food intake in these restricted primates are consistent with the retardation of disease and extension of lifespan that has been demonstrated for food restricted non-primate species. If the phenomenon can be confirmed in primates, there would be a clearer potential for manipulating the course of aging by nutritional intervention in humans.

This work is conducted at the Wisconsin Primate Research Center, one of only eight such centers in the nation. Our center is home to approximately 1500 monkeys. Research on the biology of aging is one of the major themes of our overall program, which involves nearly 250 investigators.

Representative Publications
Colman, R.J., Anderson, R.M., Johnson, S.C., Kastman, E.K., Kosmatka, K.J., T. Beasley, T.M., Allison, D.B., Cruzen, C., Simmons, H.A., Kemnitz, J.W., & Weindruch, R. (2009). Caloric restriction delays disease onset and mortality in rhesus monkeys. Science, 325, 201-204.

Fowler, C.G., Chiasson, K.B., Hart, D.B., Beasley, T.M., Kemnitz, J., & Weindruch, R. (2008). Tympanometry in rhesus monkeys: effects of aging and caloric restriction. Int. J. Audiol., 47(4), 209-14.

Zhou, R., Bruns, C.M., Bird, I.M., Kemnitz, J.W., Goodfriend, T.L., Dumesic, D.A., & Abbott, D.H. (2007). Pioglitazone improves insulin action and normalizes menstrual cycles in a majority of prenatally androgenized female rhesus monkeys. Reprod. Toxicol., 23(3), 438-48.

Raman, A., Ramsey, J.J., Kemnitz, J.W., Baum, S.T., Newton, W., Coleman, R.J., Weindruch, R., Beasley, M.T., & Schoeller, D.A. (2007). Influences of calorie restriction and age on energy expenditure in the rhesus monkeys. Am. J. Physiol., 292, E101-6.

Raman, A., Baum, S.T., Colman, R.J., Kemnitz, J.W., Weindruch, R., & Schoeller, D.A. (2007). Metabolizable energy intake during long-term calorie restriction in rhesus monkeys. Exp. Gerontol., 42(10), 988-94.

Blanc, S., Colman, R., Kemnitz, J., Weindruch, R., Baum, S., Ramsey, J., & Schoeller, D. (2005). Assessment of nutritional status in rhesus monkeys: comparison of dual-energy X-ray absorptiometry and stable isotope dilution. J. Med. Primatol., 34(3), 130-8.

Raman, A., Colman, R.J., Cheng, Y., Kemnitz, J.W., Baum, S.T., Weindruch, R., & Schoeller, D.A. (2005). Reference body composition in adult rhesus monkeys: glucoregulatory and anthropometric indices. J. Gerontol. A. Biol. Sci. Med. Sci., 60(12), 1518-24.

Ramsey, J.J., Kemnitz, J.W., Newton, W., Hagopian, K., Patterson, T.A., & Swick, A.G. (2005). Food intake in rhesus monkeys following central administration of orexins. Regul. Pept., 124(1-3), 209-14.

Bruns, C.M., & Kemnitz, J.W. (2004). Sex hormones, insulin sensitivity, and diabetes mellitus. ILAR J., 45(2), 160-9.

Zondervan, K.T., Weeks, D.E., Colman, R.C., Cardon, L.R., Hadfield, R., Scheffler, J., Goudy, T.A, Coe, C.L., Kemnitz, J.W., & Kennedy, S.H. (2004). Familial aggregation of endometriosis in a large pedigree of rhesus macaques. Human Reproduction, 19, 448-455.

Bruns, C.M., Baum, S.T., Colman, R.J., Eisner, J.R., Kemnitz, J.W., Weindruch, R., & Abbott, D.H. (2004). Insulin resistance and impaired insulin secretion in prenatally androgenized male rhesus monkeys. J. Clin. Endocrinol. Metab., 89(12), 6218-23.

Blanc, S., Schoeller, D., Kemnitz, J., Weindruch, R., Colman, R., Newton, W., Wink, K., Baum, S., & Ramsey, J. (2003). Energy expenditure of rhesus monkeys subjected to 11 years of dietary restriction. J. Clin. Endocrinol. Metab., 88, 16-23.

Fowler, C.G., Torre, P., & Kemnitz, J.W. (2002). Effects of dietary restriction and aging on the auditory function of rhesus monkeys (Macaca mulatta): The University of Wisconsin Study. Hearing Research, 169, 24-35.

Gresl, T.A., Colman, R.J., Roecker, E.B., Havighurst, T.C., Huang, Z., Allison, D.B., Bergman R.N., & Kemnitz, J.W. (2002). Dietary restriction and glucose regulation in aging rhesus monkeys: A follow-up report at 8.5 years. American Journal of Physiology: Endocrinology and Metabolism, 281, E757-765.

Ramsey, J.J., Laatsch, J.L., & Kemnitz, J.W. (2000). Age and gender differences in body composition, energy expenditure, and glucoregulation of adult rhesus monkeys. Journal of Medical Primatology, 29(1), 11-19.

Kemnitz, J.W., Roecker, E.B., Haffa, A.L., Pinheiro, J., Kurzman I., Ramsey, J.J., & MacEwen, E.G. (2000). Serum dehydroepiandrosterone sulfate concentrations across the life span of laboratory-housed rhesus monkeys. J. Med. Primatol., 29(5), 330-337.

Ramsey, J.J., Colman, R.J., Binkley, N.C., Christensen, J.D., Gresl, T.A., Kemnitz, J.W., & Weindruch, R. (2000). Dietary restriction and aging in rhesus monkeys: The University of Wisconsin Study. Exp. Gerontol., 35, 1131-1149.

Schroederus, K.M, Gresl, T.A, & Kemnitz, J.W. (1999). Reduced water intake but normal response to acute water deprivation in elderly rhesus monkeys. Aging: Clinical and Experimental Research, 11, 101-108.

Colman, R., & Kemnitz, J.W. (1998). Aging experiments using nonhuman primates. In B.P. Yu (Ed.), Methods in aging research. Boca Raton: CRC.

Colman, R.J., Roecker, E.B., Ramsey, J.J.,& Kemnitz, J.W. (1998). The effect of dietary restriction on body composition in adult male and female rhesus macaques. Aging: Clinical and Experimental Research, 10, 83-92.

Kemnitz, J.W., Holston, K.A., & Colman, R.J. (1998). Nutrition, aging and reproduction in rhesus monkeys. In W. Hansel, G.A. Bray, & D.H. Ryan (Eds.), Pennington Center Nutrition Series. Part IV. Evolution of research methods in nutrition and reproduction. Baton Rouge: Louisiana State University Press.

Uno, H., Alsum, P., Zimbric, S.M.L., Houser, W.D., Thomson, J.A., & Kemnitz, J.W. (1998). Colon cancer in aged captive rhesus monkeys (Macaca mulatta). American Journal of Primatology, 44, 19-27.

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