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. 1981 Jul;68(1):75–84. doi: 10.1172/JCI110256

Structure and function changes in the endocrine pancreas of aging rats with reference to the modulating effects of exercise and caloric restriction.

E P Reaven, G M Reaven
PMCID: PMC370774  PMID: 7019247

Abstract

The current study was conducted to determine if physical activity and/or weight control could influence the age-related decrease in beta cell insulin response noted in earlier studies. As such, virgin, male Sprague-Dawley rats were maintained in our facility for 1 yr on three differential experimental programs; in the first group, control rats lived under standard laboratory conditions; the second group of rats ran several miles a day in exercise wheels, and the third group was given a calorie-restricted diet designed to keep the rats weight-matched with the exercising rats. The results showed that the 12-mo-old sedentary control rats weighed an average of 800g. From the time these rats were 4 mo old, they were significantly hyperinsulinemic, with mean (+/- SEM) serum insulin levels of 55 +/- 6 microU/ml. Morphological studies on the pancreas of these rats at the end of the year revealed enlarged, multilobulated, fibrotic islets. After collagenase digestion, the most normal-appearing islets from the 12-mo-old controls were used for insulin secretion studies, these islets showed significantly reduced glucose-induced insulin release (0.83 microU insulin/min per volume islet) compared with islets from young rats (1.80 microU insulin/min per volume islet). In contrast, 12-mo-old exercised or calorie-restricted rats weighed approximately 500 g and did not show the changes in serum insulin levels or pancreas pathology exhibited by the sedentary control animals. However, islets from the calorie-restricted group functioned in vitro no better than islets from he sedentary control group. Islets from the exercised rats were somewhat improved in this regard. In summary, we believe exercise and weight control diminishes the animals' need for insulin-resulting in youthful-appearing islets after a year's time. However, these regimes do not appear able to correct the beta cell decline in function previously described.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Björntorp P., Fahlén M., Grimby G., Gustafson A., Holm J., Renström P., Scherstén T. Carbohydrate and lipid metabolism in middle-aged, physically well-trained men. Metabolism. 1972 Nov;21(11):1037–1044. doi: 10.1016/0026-0495(72)90034-0. [DOI] [PubMed] [Google Scholar]
  2. Desbuquois B., Aurbach G. D. Use of polyethylene glycol to separate free and antibody-bound peptide hormones in radioimmunoassays. J Clin Endocrinol Metab. 1971 Nov;33(5):732–738. doi: 10.1210/jcem-33-5-732. [DOI] [PubMed] [Google Scholar]
  3. Goulder T. J., Alberti K. G., Jenkins D. A. Effect of added fiber on the glucose and metabolic response to a mixed meal in normal and diabetic subjects. Diabetes Care. 1978 Nov-Dec;1(6):351–355. doi: 10.2337/diacare.1.6.351. [DOI] [PubMed] [Google Scholar]
  4. Hadden D. R., Montgomery D. A., Skelly R. J., Trimble E. R., Weaver J. A., Wilson E. A., Buchanan K. D. Maturity onset diabetes mellitus: response to intensive dietary management. Br Med J. 1975 Aug 2;3(5978):276–278. doi: 10.1136/bmj.3.5978.276. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Hajdu A., Herr F., Rona G. The functional significance of a spontaneous pancreatic islet change in aged rats. Diabetologia. 1968 Jan;4(1):44–47. doi: 10.1007/BF01241032. [DOI] [PubMed] [Google Scholar]
  6. Hajdu A., Rona G. Morphological observations on spontaneous pancreatic islet changes in rats. Diabetes. 1967 Feb;16(2):108–110. doi: 10.2337/diab.16.2.108. [DOI] [PubMed] [Google Scholar]
  7. Kolterman O. G., Reaven G. M., Olefsky J. M. Relationship between in vivo insulin resistance and decreased insulin receptors in obese man. J Clin Endocrinol Metab. 1979 Mar;48(3):487–494. doi: 10.1210/jcem-48-3-487. [DOI] [PubMed] [Google Scholar]
  8. Mondon C. E., Dolkas C. B., Reaven G. M. Site of enhanced insulin sensitivity in exercise-trained rats at rest. Am J Physiol. 1980 Sep;239(3):E169–E177. doi: 10.1152/ajpendo.1980.239.3.E169. [DOI] [PubMed] [Google Scholar]
  9. Reaven E. P., Gold G., Reaven G. M. Effect of age on glucose-stimulated insulin release by the beta-cell of the rat. J Clin Invest. 1979 Aug;64(2):591–599. doi: 10.1172/JCI109498. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Reaven E., Gold G., Reaven G. Effect of age on leucine-induced insulin secretion by the beta-cell. J Gerontol. 1980 May;35(3):324–328. doi: 10.1093/geronj/35.3.324. [DOI] [PubMed] [Google Scholar]
  11. Savage P. J., Bennion L. J., Flock E. V., Nagulesparan M., Mott D., Roth J., Unger R. H., Bennett P. H. Diet-induced improvement of abnormalities in insulin and glucagon secretion and in insulin receptor binding in diabetes mellitus. J Clin Endocrinol Metab. 1979 Jun;48(6):999–1007. doi: 10.1210/jcem-48-6-999. [DOI] [PubMed] [Google Scholar]
  12. Shino A., Matsuo T., Iwatsuka H., Suzuoki Z. Structural changes of pancreatic islets in genetically obese rats. Diabetologia. 1973 Oct;9(5):413–421. doi: 10.1007/BF01239438. [DOI] [PubMed] [Google Scholar]
  13. Stanik S., Marcus R. Insulin secretion improves following dietary control of plasma glucose in severely hyperglycemic obese patients. Metabolism. 1980 Apr;29(4):346–350. doi: 10.1016/0026-0495(80)90008-6. [DOI] [PubMed] [Google Scholar]
  14. WEXLER B. C., FISCHER C. T. ABNORMAL GLUCOSE TOLERANCE IN REPEATEDLY BRED RATS WITH ARTERIOSCLEROSIS. Nature. 1963 Oct 12;200:133–136. doi: 10.1038/200133a0. [DOI] [PubMed] [Google Scholar]
  15. WEXLER B. C., FISCHER C. T. HYPERPLASIA OF THE ISLETS OF LANGERHANS IN BREEDER RATS WITH ARTERIOSCLEROSIS. Nature. 1963 Oct 5;200:33–37. doi: 10.1038/200033a0. [DOI] [PubMed] [Google Scholar]

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