Pancreatic islet cell tumors found in rats given alloxan and nicotinamide.

Morphological and biochemical studies were performed in pancreatic islet cell tumors found in rats given alloxan (40 mg/kg) and nicotinamide (305 mg/kg). Complete serial sections of the whole pancreas, combined with planimetric analysis, uncovered islet cell tumors in 5 of 7 rats which were killed 10 to 14 months after treatment. Hypoglycemia associated with hyperinsulinemia was found in a rat which developed a tumor which consisted of cells which reacted lightly with aldehyde fuchsin. Another rat developed a gross tumor which was composed of cells stained deeply with aldehyde fuchsin. However, flat insulin response to glucose associated with glucose intolerance was found in this rat. In addition to B cells, a few A and D cells were found within the two tumors. The present study suggests that pancreatic islet cell tumors found in rats given alloxan and nicotinamide are composed of at least three endocrine cell populations, although the majority of tumor cells are insulin-producing B cells.