Funktionelle Entwicklung der Signalübertragung an den Zapfenphotorezeptor-Bandsynapsen in der Mausretina
Molekulare Biologie und Physiologie von Nerven- und Gliazellen
Zusammenfassung der Projektergebnisse
In our study, using various electrophysiological techniques and electron microscopy and highresolution light microscopy, we set out to examine the development of key physiological properties of cone photoreceptor ribbon synapses in the mouse retina during postnatal development (P6 – P90). The key findings of our study were: Spontaneous release of synaptic vesicles occurred independently from the development of cone photoreceptor synapses. - The concomitant release of more than one synaptic vesicle was occurring throughout the postnatal development of cone photoreceptor synapses. - AZs and synaptic ribbons increased in number during postnatal development of cone photoreceptor terminals. - We found a pool size of 200 SVs in P8–9 and P12–13, which rose to more than 900 SVs at >P30 in cone photoreceptors. The relation between structural and physiological properties of the synapse suggests that the presence of a synaptic ribbon at the AZ increases the readily releasable pool. - The replenishment rate was significantly faster at >P30 than in younger age groups. - Release probability showed no significant difference between all age groups measured and both mature and immature cone photoreceptors had a release probability close to one. - The recovery from synaptic depression was not significantly different among the examined age groups. - The slope of Ca2+ cooperativity was 2 at P8-9 which suggests a microdomain organization of the Ca2+ channels at the AZ. From the eye-opening period, the slope of Ca2+ cooperativity was 1 which indicates a nanodomain organization of Ca2+ channels. Postnatally developing mouse HCs consist of a variety of ion channels such as T-type calcium, TTX-sensitive sodium, and high voltage-activated Ca2+ channels. - T-type Ca2+ channels extend adult cone photoreceptor light-responsive membrane potential range, amplify dark responses, generate spikes, increase intracellular Ca2+ levels, and boost synaptic transmission.
Projektbezogene Publikationen (Auswahl)
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Analysis of tetrodotoxin-sensitive sodium and low voltage-activated calcium channels in developing mouse retinal horizontal cells. Experimental Eye Research, 195, 108028.
Feigenspan, Andreas; Ohs, Alexandra; von Wittgenstein, Julia; Brandstätter, Johann Helmut & Babai, Norbert
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Functional and Structural Development of Mouse Cone Photoreceptor Ribbon Synapses. Investigative Opthalmology & Visual Science, 63(3), 21.
Davison, Adam; Gierke, Kaspar; Brandstätter, Johann Helmut & Babai, Norbert
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Synaptic vesicle release during ribbon synapse formation of cone photoreceptors. Frontiers in Cellular Neuroscience, 16.
Davison, Adam; Gierke, Kaspar; Brandstätter, Johann Helmut & Babai, Norbert
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T-Type Ca2+ Channels Boost Neurotransmission in Mammalian Cone Photoreceptors. The Journal of Neuroscience, 42(33), 6325-6343.
Davison, Adam; Lux, Uwe Thorsten; Brandstätter, Johann Helmut & Babai, Norbert
