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Brain-derived neurotrophic factor and basic fibroblast growth factor downregulate NMDA receptor function in
C Brandoli1, A Sanna, M A De Bernardi
1Department of Cell Biology, Division of Neurobiology, Georgetown University, School of Medicine, Washington, DC 20007, USA.
Summary
Brain-derived neurotrophic factor (BDNF) and basic fibroblast growth factor (FGF2) protect cerebellar granule cells from excitotoxicity by reducing NMDA receptor function. These neurotrophic factors decrease NMDA receptor subunit expression, thereby lowering intracellular calcium levels and preventing neuronal damage.
Area of Science:
- Neuroscience
- Molecular Biology
- Cell Biology
Background:
- N-methyl-D-aspartate (NMDA) receptors are implicated in neuronal degeneration following hypoxia, ischemia, or trauma.
- Cerebellar granule cells are susceptible to NMDA-induced excitotoxicity.
- Brain-derived neurotrophic factor (BDNF) and basic fibroblast growth factor (FGF2) exhibit protective effects against NMDA excitotoxicity, but their molecular mechanisms remain unclear.
Purpose of the Study:
- To investigate if BDNF and FGF2 protect cerebellar granule cells from NMDA excitotoxicity by downregulating NMDA receptor function.
- To elucidate the molecular mechanisms underlying the neuroprotective properties of BDNF and FGF2.
Main Methods:
- Primary cultures of rat cerebellar granule cells were treated with BDNF or FGF2.
- Western blot and RNase protection assays were used to analyze NMDA receptor subunit expression (NR1, NR2A, NR2B, NR2C).
- Single-cell fura-2 fluorescence ratio imaging assessed NMDA-evoked intracellular calcium ([Ca2+]i) increases.
Main Results:
- FGF2 and BDNF treatment led to a time-dependent decrease in the expression of NR2A and NR2C NMDA receptor subunits.
- BDNF and FGF2 significantly reduced NMDA-mediated increases in intracellular calcium ([Ca2+]i).
- The reduction in NMDA-evoked [Ca2+]i responses correlated with the downregulation of NR2A and NR2C subunit expression.
Conclusions:
- BDNF and FGF2 protect cerebellar granule cells against NMDA-induced excitotoxicity.
- These neurotrophic factors exert their protective effects by downregulating the expression of specific NMDA receptor subunits (NR2A and NR2C).
- This downregulation leads to reduced NMDA receptor function and decreased intracellular calcium influx, thereby preventing excitotoxic neuronal injury.