Insulin-like growth factor 1 (IGF1) and its active peptide (1-3)IGF1 enhance the expression of synaptic markers in neuronal circuits through different cellular mechanisms

► Both IGF1 and (1-3)IGF1 enhance the phosphorylation of the IGF1 receptor. ► Both IGF1 and (1-3)IGF1 enhance the expression of synapsin and PSD95. ► IGF1 and (1-3)IGF1 act through different signaling pathways. ► (1-3)IGF1 enhances the expression of endogenous IGF1.