Changes of hippocampal signaling protein levels during postnatal brain development in the rat

Developmental regulation of individual signaling proteins in the brain has been reported, although no systematic approach to study postnatal signaling protein expression in the rat has been described. This formed the rationale to compare hippocampal protein levels in rat hippocampus at different developmental time points. Sprague-Dawley rats at 3 days, 3 weeks, and 3 months of age were used, hippocampi were extirpated, proteins extracted and run on two-dimensional gel electrophoresis with subsequent identification of protein spots by mass spectrometry. Identified signaling proteins were quantified by specific software and for between group comparison Fisher's exact or Mann-Whitney U tests were applied. Annexin A3, GTP-binding nuclear protein RAN, phosphatidylethanolamine-binding protein, adenylyl cyclase associated protein 1, Rho-associated protein kinase 1, nucleoside diphosphate kinase A, LIM, and SH3 domain protein 1 were developmentally regulated. High-abundance hippocampal signaling proteins from several cascades in three different postnatal stages are presented, showing temporal regulation of signaling protein levels that have not been described in literature so far. Results are relevant for design and interpretation of further studies at the protein level and, moreover, an analytical tool concomitantly determining regulation of a large series of signaling proteins in the hippocampus is provided. These data contribute to the understanding that different time points may use different signaling cascades.