Effect of protein deprivation and a reduced diet on the regenerating rat liver.

In rats fed a protein-free, calorie rich diet DNA synthesis is reduced, the mitotic index diminished and the proliferative response imparied. Nevertheless protein deficient hepatocytes retain a remarkable ability to hypertrophy and proliferate after partial hepatectomy. In pair-fed rats on a reduced semi-stravation diet deficient in calories these same parameters are not only diminished but their onset is also delayed. Electron microscopy revealed that the glycogen in the liver cells of these rats was severely depleted. This depletion was considered to be a critical factor in the delayed response to partial hepatectomy. Both groups showed a marked reduction of organelles, especially ribosomes and rough endoplasmic reticulum (RER). Golgi complexes persisted and were conspicuous. Rough endoplasmic reticulum was promptly reformed following partial hepatectomy.