Synthesis of specific brain proteins is influenced by testosterone at mRNA level in the neonatal rat

Sex differences in brain protein synthesis were investigated by analyzing the in vitro translation products of poly (A)+ mRNA isolated from the hypothalamus-preoptic area of male, female and androgenized female (injected with testosterone propionate at day 4) rats at different stages of development. Poly (A)+-enriched mRNA, prepared by oligo (dT)-chromatography of total RNA extracted by guanidine thiocyanate, was translated in either a rabbit reticulocyte lysate or cell-free wheat germ system supplemented with either [35S]methionine or a [3H]amino acid mix. The translation products were analyzed by one- and two-dimensional SDS-PAGE. Several developmental and androgen-induced changes were found in the translation products of specific mRNA species, the most important of which was a sex difference (higher in the male) in the apparent amount of mRNA coding for proteins with the electrophoretic characteristics of actin and tubulin. These developmental and sex differences in the apparent amounts of specific mRNA species in brain may be the cause or result of functional and structural changes such as neurite growth and synapse formation.