Neonatal handling selectively alters the phosphorylation of a 47,000 mol. wt. protein in male rat hippocampus

Beginning on postnatal day 1, rat pups were handled for 7 min daily for 23-30 days. This treatment diminished the in vitro phosphorylation of phosphoprotein F-1 [mol. wt. approximately 47 K daltons, protein B-50] in the hippocampus of male rats. Other major phosphoproteins (D-1-2. mol. wt. 80-86 K daltons: E-2-3. mol. wt. 50-55 K daltons) were not influenced by handling. These findings confirm and extend the results of Holmes et al. who observed a decrease in ECS-induced protein kinase activity subsequent to handling.