In the hippocampus Wnts in conjunction with cell electrical activity promote synapse formation. Wnt7b is expressed in maturing dendrites, and the expression of the Wnt receptor Frizzled (Fz), increases highly with synapse formation in the hippocampus. NMDA glutamate receptor activation increases Wnt2 expression. Long term potentiation (LTP) due to NMDA activation and subsequent Wnt expression leads to Fz-5 localization at the postsynaptic active zone. Furthermore, Wnt7a and Wnt2 signaling after NMDA receptor mediated LTP leads to increased dendritic arborization and regulates activity induced synaptic plasticity. Blocking Wnt expression in the hippocampus mitigates these activity dependent effects by reducing dendritic arborization and subsequently, synaptic complexity.
