American Journal of Clinical Nutrition, Vol 24, 770-776, Copyright © 1971 by The American Society for Clinical Nutrition, Inc.

Functional nature of the polysomes as indicated by the influences of insulin-glucose and adrenalectomycortisol on rat liver polysomes in vivo

¹ From the Department of Biochemical Nutrition, Hoffmann-La Roche, Inc. Nutley, New Jersey 07110

The disaggregated liver polysomes of the fasted rat can be restored by an intravenous injection of glucose and insulin. This treatment also causes an increase in amino acid incorporation in vivo. Adrenalectomized rats have disaggregated liver polysomes and decreased amino acid incorporation in vivo. Treatment with cortisol hemisuccinate restores the polysomes, but causes a further decrease in amino acid incorporation in vivo.

These results are interpreted to mean that insulin acts on some insulin-sensitive sites in the liver, permitting glucose to preferentially change the polysome steady-state condition by affecting the relative rates of polysome breakdown (protein synthesis) and ribosomal activation to polysomes. The functional nature of the polysome is described as being a reservoir of active ribosomes that can be, but are not necessarily, used for protein synthesis.