Synaptic Vesicle Exocytosis at the Dendritic Lobules of an Inhibitory Interneuron in the Mammalian Retina

Veeramuthu Balakrishnan, Theresa Puthussery, Mean Hwan Kim, W. Rowland Taylor, Henrique Von Gersdorff

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

Ribbon synapses convey sustained and phasic excitatory drive within retinal microcircuits. However, the properties of retinal inhibitory synapses are less well known. AII-amacrine cells are interneurons in the retina that exhibit large glycinergic synapses at their dendritic lobular appendages. Using membrane capacitance measurements, we observe robust exocytosis elicited by the opening of L-type Ca2+ channels located on the lobular appendages. Two pools of synaptic vesicles were detected: a small, rapidly releasable pool and a larger and more slowly releasable pool. Depending on the stimulus, either paired-pulse depression or facilitation could be elicited. During early postnatal maturation, the coupling of the exocytosis Ca2+-sensor to Ca2+ channel becomes tighter. Light-evoked depolarizations of the AII-amacrine cell elicited exocytosis that was graded to light intensity. Our results suggest that AII-amacrine cell synapses are capable of providing both phasic and sustained inhibitory input to their postsynaptic partners without the benefit of synaptic ribbons.

Original languageEnglish (US)
Pages (from-to)563-575
Number of pages13
JournalNeuron
Volume87
Issue number3
DOIs
StatePublished - Aug 5 2015

ASJC Scopus subject areas

  • Neuroscience(all)

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