Shc-binding site in the TrkB receptor is not required for hippocampal long-term potentiation.

Recent evidence shows that neurotrophins are not only involved in neuronal survival and differentiation but also in modulating synaptic strength in the developing and adult nervous system. To understand how neurotrophins induce changes in synaptic strength, we have investigated signaling pathways downstream of the TrkB receptor, which binds brain-derived neurotrophic factor (BDNF) or NT-4/5. To test whether the Shc-site activated signaling pathway, which has been shown to be important for neuronal survival in vivo, also plays a role in processes like long-term potentiation (LTP), we have generated a mouse strain carrying a mutation in the Shc-binding site of the TrkB receptor. In hippocampal slices from these mice we investigated whether basal synaptic transmission, early-LTP (E-LTP) or late-LTP (L-LTP) were affected by this mutation. We found that homo- and heterozygous mutant mice show no difference in the induction-rate or magnitude of E-LTP and L-LTP induced by theta-burst or tetanus stimulation, suggesting that the Shc-binding site in the TrkB receptor and its downstream activated signaling cascade is not involved in hippocampal synaptic plasticity.