Pituitary Influence of Pyridine Nucleotide Metabolism of Rat Liver.

When nicotinamide is injected into dogs, rats, or mice, there is a transient increase in the concentration of nicotinamide adenine dinucleotide in the liver (l-5). This phenomenon has been studied in great detail by Kaplan and his colleagues and has been the subject of a number of reviews (e.g. References 6 and 7). We have observed that the maximum level of NAD reached in response to nicotinamide administration is greater, and that the level remains elevated for a longer period of time, in hypophysectomized than in normal rats (89). In the present study, this phenomenon has been explored in greater detail. The effect of hypophysectomy on liver NAD when nicotinic acid or tryptophan is used in place of nicotinamide as the precursor of the pyridine moiety of NAD has also been investigated.