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Two Potassium Channels in the Presynaptic and Postsynaptic Components of a Synapse
Başlık:
Two Potassium Channels in the Presynaptic and Postsynaptic Components of a Synapse
Yazar:
Zhang, Yihui, author.
ISBN:
9780438073890
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (131 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 79-10(E), Section: B.
Advisors: Hai Huang Committee members: Andrei Derbenev; Ricardo Mostany; Jeffrey Tasker.
Özet:
Reliable and precise signal transmission is essential in circuits of the auditory brainstem to encode timing with sub-millisecond accuracy. Globular bushy cells reliably and faithfully transfer spike signals to the principal neurons of the medial nucleus of the trapezoid body (MNTB) through calyx of Held, a giant glutamatergic synapse. Therefore, the MNTB works as a relay nucleus that preserves the temporal pattern of firing at high frequency. Using whole-cell patch-clamp recordings, we investigated the K+ channels that shape the reliability of signal transfer across the rat calyx-MNTB synapse.
We observed that small-conductance calcium-activated potassium (SK) channels are expressed in the postsynaptic MNTB neurons. SK channels were activated by intracellular Ca2+ sparks and mediated spontaneous transient outward currents in developing MNTB neurons. SK channels were also activated by Ca2+ influx through voltage-gated Ca2+ channels and synaptically activated by NMDA receptors. Blocking SK channels with apamin depolarized the resting membrane potential, reduced resting conductance, and affected the responsiveness of MNTB neurons to signal inputs. Moreover, SK channels were activated by action potentials and affected the spike afterhyperpolarization. Blocking SK channels disrupted the one-to-one signal transmission from presynaptic calyces to postsynaptic MNTB neurons and induced extra postsynaptic action potentials in response to presynaptic firing.
KCNQ channels are slow-activating and non-inactivating, voltage-gated K+ channels. In addition to controlling the resting properties of the presynaptic calyceal terminal, we found that KCNQ channels were cumulatively activated during high-frequency firing and contributed to maintaining the normal presynaptic action potential waveform. Blocking KCNQ channels led to the cumulative inactivation of presynaptic Na+ and Kv1 channels, and disrupted the reliable action potential waveform and calcium influx required for reliable synaptic transmission.
These data reveal that both postsynaptic SK channels and presynaptic KCNQ channels play important roles in regulating electrical activity and are crucial for reliable high-frequency signal transmission across the calyx-MNTB synapse.
Notlar:
School code: 0494
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(679064.1) | 679064-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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