Target Cell Type-Dependent Differences in Ca2+ Channel Function Underlie Distinct Release Probabilities at Hippocampal Glutamatergic Terminals

2017. december 8.

Target cell type-dependent variability in presynaptic properties is an intriguing feature of cortical synapses.When a single cortical pyramidal cell establishes a synapse onto a somatostatin-expressing interneuron (IN), the synapse releases glutamate with low probability, whereas the next bouton of the same axon has high release probability when its postsynaptic target is a parvalbumin-expressing IN. Here, we used combined molecular, imaging, and anatomical approaches to investigate the mechanisms underlying these differences. Our functional experiments implied an approximately twofold larger Ca2+channel density in high release probability boutons, whereas freeze–fracture immunolocalization demonstrated only a 15% difference in Ca2+ channel subunit densities. Our results point toward a postsynaptic target cell type-dependent regulation of Ca2+ channel function or different subunit composition as the underlying mechanism.

Larger [Ca 2+] transients in PV+ than in mGluR1α+ dendrite-contacting boutons

Reference

Tímea Éltes, Tekla Kirizs, Zoltán Nusser, and Noémi Holderith
Target Cell Type-Dependent Differences in Ca2+ Channel Function Underlie Distinct Release Probabilities at Hippocampal Glutamatergic Terminals
The Journal of Neuroscience, February 15, 2017 • 37(7):1910 –1924