Sustained intracellular Ca2+ elevation induced by a brief BDNF application in rat visual cortex neurons.

Area of Science:

• Neuroscience
• Cellular Biology
• Molecular Biology

Background:

• Brain-derived neurotrophic factor (BDNF) is crucial for neuronal survival, growth, and synaptic plasticity.
• Intracellular calcium (Ca2+) signaling plays a vital role in various neuronal functions, including synaptic transmission and gene expression.

Purpose of the Study:

• To investigate the effect of BDNF on intracellular Ca2+ dynamics in rat visual cortical pyramidal neurons.
• To elucidate the signaling pathways involved in BDNF-induced sustained Ca2+ elevation.

Main Methods:

• Primary cortical neurons were isolated from rats.
• Fura-2 imaging was used to measure intracellular Ca2+ mobilization.
• Application of BDNF (20 ng/ml) for 1-2 minutes.
• Inhibition studies using K252a (TrkB inhibitor) and U73122 (PLC inhibitor).

Main Results:

• A brief BDNF application induced a sustained increase in intracellular Ca2+ lasting over 90 minutes.
• BDNF-mediated Ca2+ elevation involved TrkB receptor tyrosine kinase activation and subsequent PLC-gamma phosphorylation.
• Both K252a and U73122 suppressed intracellular Ca2+ levels even in the absence of BDNF, indicating basal pathway activity.
• Sustained activation of TrkB and PLC-gamma contributes to the short-term maintenance (<30 min) of elevated intracellular Ca2+.

Conclusions:

• BDNF triggers a prolonged intracellular Ca2+ signaling cascade in visual cortical pyramidal neurons.
• The TrkB-PLC-gamma pathway is essential for mediating BDNF's effects on Ca2+ homeostasis.
• These findings highlight the role of BDNF in regulating neuronal excitability and plasticity through sustained Ca2+ signaling.