The synthesis of myo-inositol in the rat.

In 1924, Needham (1) observed the steady excretion of myo-inositol’ by polyuric rats subsisting on a high salt, purified diet. He took this finding as evidence that the rat can synthesize inositol, but it now seems likely that his diet contained appreciable amounts of the compound.2 A number of years later, Woolley (4) found that myo-inositol was the factor required for the prevention of an alopecia which developed in mice fed a purified ration. Since that time, the compound has been routinely added to most synthetic diets on the assumption that an exogenous source may be generally required by animals. Further attempts at the direct demonstration of this requirement have not been uniformly successful (for recent work with rats, see McCormick et al. (3)). However, it has been supposed, following Woolley (5), that many animals obtain their inositol from their intestinal flora. Until recently, there has not been available any direct evidence for the ability of animals to synthesize myo-inositol in their own tissues. During the course of a general study of the metabolism of inositol in the rat, it was observed that the output of inositol in germ-free rats over a period of 4 months was greater than the input (6,7), indicating that there had been synthesis of inositol. In the experiments reported in this paper, a new method for the isolation of the total inositol of animal tissues was developed, and the synthesis of inositol in the adult rat was confirmed by the isolation of radioactive inositol from animals which had received glucosel-CY4. While these studies were in progress, Daughaday, Larner, and