The effect of ionizing radiation on the primate pancreas: an endocrine and morphologic study.

In this study we evaluated the endocrine, biochemical, and haematological derangements as well as pancreatic and histological changes of the bonemarrow in the primate following external fractionated subtotal marrow irradiation without bonemarrow reconstitution. The irradiation was administered in preparation for pancreatic transplantation. Two groups of animals (ten in each group) received 800 rad (8 Gy) and 1,000 rad (10 Gy) respectively over 4 to 5 weeks. A maximum of 200 rads (2 Gy) were administered weekly as photons from a 6 MV linear accelerator. During irradiation the animals remained normoglycaemic in the presence of transiently elevated liver enzymes and serum amylase values, which returned to normal on completion of the irradiation. Insulin release was significantly reduced in both groups during irradiation and was associated with minimally decreased K-values in the presence of mild glucose intolerance. Pancreatic light morphologic changes included structural changes of both exocrine and endocrine elements and included necrosis of the islet cells and acinar tissue. Islet histology demonstrated striking cytocavitary network changes of alpha and beta cells, including degranulation, vacuolization, mitochondrial destruction, and an increase in lysosomes. A hypoplastic bonemarrow ranging from moderate to severe was observed in all irradiated recipients. Near total fractionated body irradiation in the primate is therefore associated with elevated liver enzymes, pancytopenia, transient hyperamylasaemia, hypoinsulinaemia, a varying degree of pancreatitis, and bonemarrow hypoplasia.