Dinitrophenol in Diet,on Growth and Duration of Life of the White Rat. ∗

Conclusions

Alpha dinitrophenol, added to the diet of white rats in up to maximum non-fatal concentrations, slowed down the rate of growth not more than about 19%, and did not significantly modify the body weight reached at the end of from 350 to 450 days, or in about 1/3 to 1/2 the span of life.

In connection with the present extensive clinical use of dinitrophenol (2–4 or alpha) in treating metabolic disorders or obesity, an important problem is the possible influence of the drug on the rate of growth and duration of life. Experiments on this problem have been in progress for 18 months in this laboratory and may be reported in a preliminary way now.

Three separate series of feeding experiments are being conducted, using white rats from the same strain. The rats are fed a standard adequate diet, to which are added the required amounts of alpha dinitrophenol with thorough mixing to ensure homogeneity. Food and water consumption and weights of rats are recorded at 3-day intervals. The rats are divided into groups of 5 or 6 and given the dinitrophenol in concentrations ranging from 0.0002 to 0.24%, starting shortly after weaning.

All the rats on 0.24% died before the 90th day, and 3 of those on 0.12% died by the 275th day. The lower concentrations were well tolerated as far as fatalities were concerned. Inspection of Table I shows that there was a small degree of slowing of rate of growth in the higher dosage groups. The greatest retardation at any time, with concentrations of 0.08% or less, was never more than 19%. The final weights of the surviving animals do not vary significantly from the weights of the controls.

The metabolic rates of these rats, their food and water intakes, duration of life, pathologic changes in tissues, etc., will be presented in detail at the conclusion of the study.

Conclusions. Alpha dinitrophenol, added to the diet of white rats in up to maximum non-fatal concentrations, slowed down the rate of growth not more than about 19%, and did not significantly modify the body weight reached at the end of from 350 to 450 days, or in about 1/3 to 1/2 the span of life.