Brain Slice Protein Degradation and Development

Abstract

Protein degradation rates were measured in brain slices prepared from rats of various ages. This was done by adding the protein synthesis rate, determined by incorporation of a labeled precursor, and the net protein degradation rate, determined by measuring the changes with time of total free amino acids. These rates were 30% higher than rates previously calculated from protein synthesis rates and protein accumulation rates in vivo. The protein degradation rates in brain slices diminished with age; i.e., 2 day cerebellum > 2 day cerebral hemisphere < 12 day cerebral hemisphere > young adult cerebral hemisphere. Protein degradation rates in slices from young brain were initially slightly higher than protein synthesis rates, resulting in a small net degradation with time. Unlike slices from adult brain, the protein degradation rates in slices from young brain declined only modestly with time for up to 100 min of incubation. The characteristics of protein degradation in brain slices from young animals were roughly similar to protein degradation in vivo. This system may prove useful for studying factors which control or affect brain protein degradation.