Biology subjects

Dufor, T.

Publications and source records attributed to Dufor, T..

3 recordsLinked to original sources

bioRxiv2026

Age-related cerebellar genetic, neuronal and functional impairments are reversed by specific magnetic stimulation protocols

Age-related cognitive decline reflects progressive atrophic changes that advance through broad neural networks. There is no effective treatment. However, brain ageing is not homogenous, so treating the earliest-affected circuits may be successful in reversing and/or preventing ongoing neuronal atrophy and therefore cognitive decline. Repetitive transcranial magnetic stimulation (rTMS), a non-invasive technique that modulates cortical excitability, induces activity-dependent neuronal plasticity. Here we investigate short- and long-term effects of low intensity rTMS (LI-rTMS) on the cerebellum, which is adversely affected early during ageing. With age, cerebellar genes related to inflammation are strongly upregulated, whereas processes of synaptic-maintenance are reduced. Both abnormalities are rapidly corrected by LI-rTMS in a protocol-dependent manner. In parallel, LI-rTMS increases neuronal spine density and dendritic complexity, in association with improved spatial memory in both young adult and aged mice. These responses of the ageing cerebellum to low-intensity magnetic stimulation are extremely encouraging for treating age-related cognitive decline, but reinforce that appropriate stimulation parameters must be identified for effective treatment.

neuroscience↗

bioRxiv2022

A genetic variant of the Wnt receptor LRP6 accelerates synapse degeneration during ageing and in Alzheimer's disease

Synapse loss strongly correlates with cognitive decline in Alzheimers Disease (AD), but the underlying mechanisms are poorly understood. Studies suggest that deficient Wnt signalling, a pathway required for neuronal connectivity, contributes to synapse dysfunction and loss in AD. Consistent with this idea, a variant of Lrp6, (Lrp6-val), which confers reduced Wnt signalling, has been linked to late onset AD. However, the impact of Lrp6-val on synapses in the healthy and AD brain has not been examined. Using CRISPR/Cas9 genome editing, we generated a novel knock-in mouse model carrying this Lrp6 variant to study its role in synaptic integrity. Lrp6-val mice develop normally and do not exhibit morphological brain abnormalities. Hippocampal neurons from Lrp6-val mice do not respond to Wnt7a, a Wnt ligand that promotes synaptic assembly through the Frizzled-5 (Fz5) receptor. Activation of the Wnt pathway by Wnt ligands leads to the formation of a complex between LRP6 and Fz5. In contrast, LRP6-Val impairs the formation of the LRP6-Fz5 complex elicited by Wnt7a, as detected by proximity ligation assay (PLA). We demonstrate that Lrp6-val mice exhibit structural and functional synaptic defects that become more pronounced with age, consistent with decreased canonical Wnt signalling during ageing. To investigate the contribution of this variant to AD, Lrp6-val mice were crossed to hAPPNL-G-F/NL-G-F (NL-G-F), a knock-in AD mouse model. The presence of the Lrp6-val variant significantly exacerbates synapse loss around amyloid-{beta} plaques in NL-G-F mice. Our findings uncover a novel role for the Lrp6-val variant in synapse vulnerability during ageing and its contribution to synapse degeneration in AD.

neuroscience↗

bioRxiv2018

Neural circuit repair by low-intensity magnetic stimulation requires cryptochrome

Magnetic brain stimulation is a promising treatment in neurology and psychiatry, but clinical outcomes are variable. Unfortunately, mechanisms underlying magnetic stimulation effects are ill-defined, which impedes the development of stimulation protocols appropriate for different neurological conditions. Here we show, in vivo and ex vivo, that repetitive transcranial magnetic stimulation at low-intensity (LI-rTMS) induces axon outgrowth and synaptogenesis to repair a neural circuit. This repair depends on stimulation pattern, with complex patterns being particularly effective, and its mechanism requires the presence of cryptochrome (Cry), a putative magneto-receptor. Effective LI-rTMS patterns altered expression of Cry target genes known to promote neuronal repair. Because LI-rTMS generates electric fields too weak to depolarise neurons, these findings indicate that the magnetic field itself induces the repair. Our data open a new framework for magnetic stimulation - cryptochrome-mediated molecular and structural neuroplasticity. This information suggests new routes to treatments specific for each neurological disease.

neuroscience↗