Postsynaptic IP3 receptor-mediated Ca2+ release modulates synaptic transmission in hippocampal neurons

Area of Science:

• Neuroscience
• Cellular Biology
• Molecular Biology

Background:

• Calcium (Ca2+) signaling is vital for synaptic transmission.
• Inositol 1,4,5-trisphosphate receptors (IP(3)Rs) are key mediators of intracellular Ca2+ release.

Purpose of the Study:

• To investigate the role of postsynaptic IP(3)R-mediated Ca2+ release in regulating synaptic transmission in hippocampal CA1 neurons.
• To explore the developmental regulation and molecular pathways involved in IP(3)R-mediated synaptic plasticity.

Main Methods:

• Whole-cell perfusion techniques in postsynaptic hippocampal CA1 neurons.
• Application of IP(3)R agonists and antagonists.
• Inhibition of Ca2+/calmodulin, protein kinase C (PKC), Ca2+/calmodulin-dependent protein kinase II (CaMKII), and smooth endoplasmic reticulum (SER) Ca2+-ATPases.
• Electrophysiological recordings of excitatory postsynaptic currents (EPSCs) and spontaneous EPSCs.

Main Results:

• IP(3)R agonists significantly enhanced excitatory postsynaptic current (EPSC) amplitudes.
• These enhancements were developmentally regulated and correlated with type-1 IP(3)R expression.
• Inhibitors of Ca2+/calmodulin, PKC, CaMKII, and SER Ca2+-ATPases modulated IP(3)R agonist effects.
• IP(3)R activation converted silent to active synapses and increased spontaneous EPSC frequency.

Conclusions:

• Postsynaptic Ca2+ release from intracellular stores, mediated by IP(3)Rs, plays a critical role in regulating postsynaptic AMPA receptor (AMPAR) function.
• This mechanism contributes to synaptic plasticity and function in the hippocampus.