The effects of hypersecretion of growth hormone and prolactin on islet endocrine cells have been studied by radioimmunoassays, immunocytochemistry, and morphometry in randomized samples of pancreata from MtTW15 mammosomatotropic tumor-bearing and control rats. The randomized sampling procedure, validated by immunoassays, allowed evaluation of both hormone content (immunoassay) and endocrine cell population (immunocytochemistry) on samples derived from the same origin. Hyperinsulinemia (2×) and non-fasting hypoglycemia in 10-wk-tumor rats were normalized 3 wk after tumor removal. Pancreatic weight was doubled, but proportional to body weight increases. Islet/pancreas ratio was constant (1.29 ± 0.05%) and the same in tumor, tumor-removed, and control animals, but average islet dimensions were increased by 30% and average area doubled in tumor animals. Frequency analysis showed fewer small (< 70 μm) and more large (> 140 μm) islets in tumor animals, but no change in average islet shape shown by average axis ratios of 1.4 in all groups. Pancreatic content of insulin and glucagon was doubled, while that of somatostatin was constant. These changes were not completely reversed in tumor-removed animals. Similarly, a significant doubling in islet-derived mass was mainly due to a doubling of the B-cell mass as the average proportion of endocrine cells per islet shifted from 66%, 26%, and 18% to 81%, 18%, and 3% for B-, A-, and D-cells of control and tumor-bearing rats, respectively. Immunocytochemically detectable insulin was found in duct cells of tumor animals, but not controls. Whether such cells represent a functional reserve remains to be determined.
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Original Articles|
January 01 1983
Effect of MtTW15 Mammosomatotropic Tumors on Pancreatic Islet Hormones
Jonathan A Parsons;
Jonathan A Parsons
Department of Anatomy, University of Minnesota, School of Medicine
Minneapolis, Minnesota
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Margaret A Hartfel;
Margaret A Hartfel
Department of Anatomy, University of Minnesota, School of Medicine
Minneapolis, Minnesota
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Orion D Hegre;
Orion D Hegre
Department of Anatomy, University of Minnesota, School of Medicine
Minneapolis, Minnesota
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Robert C McEvoy
Robert C McEvoy
Department of Anatomy, Mount Sinai School of Medicine, The Mount Sinai Hospital
New York, New York
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Address reprint requests to Jonathan A. Parsons, Ph.D., Department of Anatomy, 4-135 Jackson Hall, University of Minnesota, 321 Church Street S.E., Minneapolis, Minnesota 55455.
Citation
Jonathan A Parsons, Margaret A Hartfel, Orion D Hegre, Robert C McEvoy; Effect of MtTW15 Mammosomatotropic Tumors on Pancreatic Islet Hormones. Diabetes 1 January 1983; 32 (1): 67–74. https://doi.org/10.2337/diab.32.1.67
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