Some Metabolic and Endocrine Changes due to Long Lasting Caloric Undernutrition

Abstract

The adaptation of rats to 6 weeks of intermittent starvation was studied. (1) The growth decrement of underfed rats can be compensated for during realimentation if somatotropic hormone is administered when the growth curve flattens out. The virtual (calculated) period of growth of adapted animals is significantly longer than that of control animals. (2) In animals adapted to intermittent starvation the weight of the seminal vesicles was larger than that of control animals even after 30 weeks of realimentation. (3) In rats underfed by daily restriction of caloric intake the amount of collagen in the liver decreases whereas in the lungs it increases in spite of undernutrition. Results are discussed with respect to the findings of McCay concerning the prolongation of life in underfed rats. All indicators studied and also results published elsewhere concerning the increased capacity for growth of tissues in vitro in underfed animals indicate that the biological age of underfed rats is decreased.