Inhibiting Effect of Nicotinamide and Diphosphopyridine Nucleotide on the Methylcholanthrene Sarcoma in Rats

RECENTLY, Oide 1 reported that when a pellet of nicotinamide was intrasplenically implanted in rats after partial removal of the liver, the numbers of mitoses in the liver were greatly reduced. Further, Fujii and Mizuno 2 demonstrated that this compound has a marked inhibitory effect on the epidermal hyperplasia induced by painting with methylcholanthrene. We attempted to study the influence of the subcutaneous injection of nicotinamide and diphosphopyridine nucleotide (DPN) on the incidence and growth of tumours induced by subcutaneous injection of methylcholanthrene. For this experiment 36 Wistar strain rats weighing about 125 gm. were used. These were divided into three groups, each of which consisted of 12 animals. Rats in each group received subcutaneous injection of 0.25 ml. of cold sterile distilled water (group 1), 1 per cent nicotinamide (supplied by Katayama Chemical Works, Japan) (group 2) or 0.1 per cent DPN (supplied by Nutritional Biochemicals Corp., U.S.A.) (group 3) respectively.