Synapse-to-synapse variation of calcium channel subtype contributions in large mossy fiber terminals of mouse hippocampus

K. Miyazaki, T. Ishizuka, H. Yawo

    Research output: Contribution to journalArticlepeer-review

    14 Citations (Scopus)

    Abstract

    Both N- and P/Q-type voltage-dependent calcium channels are involved in fast transmitter release in the hippocampus, but are differentially regulated. Although variable contributions of voltage-dependent calcium channel subtypes to presynaptic Ca2+ influx have been suggested to give a neural network of great diversity, their presence has only been demonstrated in a culture system and has remained unclear in the brain. Here, the individual large mossy fiber presynaptic terminal was labeled with Ca2+/Sr 2+-sensitive fluorescent dextrans in the hippocampal slice of the mouse. The fractional contribution of voltage-dependent calcium channel subtypes to presynaptic Ca2+/Sr2+ influx was directly measured by the sensitivity of Ca2+/Sr2+-dependent fluorescent increment to subtype-selective neurotoxins, ω-conotoxin GVIA (an N-type selective blocker), ω-agatoxin IVA (a P/Q-type selective blocker) and SNX-482 (an R-type selective blocker). Synapse-to-synapse comparison of large mossy fiber terminals revealed that the contributions of N- and R-type voltage-dependent calcium channels varied more widely than that of P/Q-type. Even two large mossy fiber presynaptic terminals neighboring on the same axon differed in the fractional contributions of N- and R-type voltage-dependent calcium channels. On the other hand, these terminals were similar in the fractional contributions of P/Q-type voltage-dependent calcium channels. These results provide direct evidence that individual large mossy fiber synapses are differential in the contribution of N- and R-type voltage-dependent calcium channel subtypes to presynaptic Ca2+/Sr2+ influx. We suggest that the synapse-to-synapse variation of presynaptic voltage-dependent calcium channel subtype contributions may be one of the mechanisms amplifying diversity of the hippocampal network.

    Original languageEnglish
    Pages (from-to)1003-1014
    Number of pages12
    JournalNeuroscience
    Volume136
    Issue number4
    DOIs
    Publication statusPublished - 2005

    Keywords

    • Brain slice
    • Calcium imaging
    • Dentate gyrus
    • Learning and memory
    • Network
    • Presynaptic

    ASJC Scopus subject areas

    • Neuroscience(all)

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