Developmental changes of protein-bound radioactivity distribution in rat brain slices incubated with labelled leucine

Abstract

The distribution of protein-bound labelled leucine in cortical slices prepared from young rats was investigated by autoradiography and complemented with measurements of the rate of protein synthesis in slices. During the second and third postnatal weeks the rate of protein synthesis in cortical slices from rat brain declined rapidly. The distribution of protein-bound radioactivity was fairly homogenous within the neuronal cell population of cortical slices from 7-day-old rats and was not influenced by the level of labelled leucine in the incubation medium (0.01 and 1 mM). On the contrary, the gradient-like distribution of incorporated radioactivity appeared in slices from 14-day-old rats, at both trace and 1 mM levels of the precursor. The laminar analysis of neuronal cell labelling confirmed the preponderance of incorporation into the neurones localized near the slice surface and the considerable inhibition of neuronal protein synthesis in the slice centre. Therefore, these limitations on the use of cortical slices for the study of brain protein synthesis in the rat should be respected from the beginning of the second postnatal week.