Effects of poly (ADP-ribose) synthetase inhibitor on b-cells of a canine pancreas after massive pancreatectomy

Nicotinamide, a poly (ADP-ribose) synthetase inhibitor, was administered intravenously to massive pancreatectomized dogs (NA group), whereas saline was administered intravenously to massive pancreatectomized dogs (saline group). Stathmokinetic studies were done to clarify the regenerating activities of B-cells. Nicotinamide significantly increased mitotic indices of B-cells after pancreatectomy (p<0.01). On the second day after pancreatectomy, mitotic index of B-cells in the NA group (2.00 ±0.20%) was higher than that in the saline group (0.25 ±0.10%). Though insulin content of pancreatic tissue decreased 2 d after pancreatectomy in the both groups, recovery of insulin content was significantly more immediate and more sufficient in the NA group. Intravenous glucose tolerance tests showed a significantly greater increase of insulin release on the 31st and 62nd day after pancreatectomy, and better glucose tolerance on the 62nd day in the NA group compared with the saline group. These results are considered to be attributed to the regenerating and protecting effects of nicotinamide on B-cells after pancreatectomy, and suggest a clinical value of nicotinamide also in man, especially for Sandmeyer's diabetes.