guanosine-diphosphate and Starvation

The aim of the present work is to investigate the effect of starvation on brown adipose tissue thermogenic activity with aging. Interscapular brown adipose tissue from female Wistar rats of different ages was used; half of them were fed and the other half were starved for 24 hours. Mitochondria were isolated and mitochondrial protein content, GDP-binding, Cytochrome-c Oxidase activity and uncoupling protein levels were measured. Results show a decrease of all studied parameters, indicating a diminished thermogenic activity with age. The response to starvation is almost the same in all the parameters studied: a general reduction with starvation and a progressive disappearance of this response to starvation with aging. On the whole, these results would indicate a deficient regulation of brown adipose tissue thermogenic activity in old animals, as it happens in other animal models with an alterated thermogenesis.

Topics: Adipose Tissue; Adipose Tissue, Brown; Age Factors; Animals; Body Temperature Regulation; Body Weight; Electron Transport Complex IV; Female; Food Deprivation; Guanosine Diphosphate; Mitochondria; Organ Size; Proteins; Rats; Rats, Wistar; Starvation

In rats, 48-h starvation causes a decrease in the rate of protein synthesis in skeletal (e.g. gastrocnemius) muscle, due largely to impairment of peptide-chain initiation. In other cell types inhibition of initiation is associated with decreased activity and recycling of initiation factor eIF-2, and increased phosphorylation of its alpha-subunit. However, 48-h starvation has no effect on the activity or recycling of eIF-2 measured in extracts of gastrocnemius muscle, or on the level of alpha-subunit phosphorylation. The effects of starvation on peptide-chain initiation in skeletal muscle must therefore involve alterations in other components of the translational machinery.

Topics: Animals; Eukaryotic Initiation Factor-2; Guanosine Diphosphate; Guanosine Triphosphate; Kinetics; Male; Muscles; Peptide Initiation Factors; Phosphorylation; Polyribosomes; Proteins; Rats; Rats, Inbred Strains; Reference Values; Ribosomes; RNA, Transfer, Met; Starvation