Anatomical and neurochemical characterization of dopaminergic interplexiform processes in mouse and rat retinas

Paul Witkovsky, R. Gábriel, David Križaj

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

Dopaminergic (DA) neurons of mouse and rat retinas are of the interplexiform subtype (DA-IPC), i.e., they send processes distally toward the outer retina, exhibiting numerous varicosities along their course. The primary question we addressed was whether distally located DA-IPC varicosities, identified by tyrosine hydroxylase (TH) immunoreactivity, had the characteristic presynaptic proteins associated with calcium-dependent vesicular release of neurotransmitter. We found that TH immunoreactive varicosities in the outer retina possessed vesicular monoamine transporter 2 and vesicular GABA transporter, but they lacked immunostaining for any of nine subtypes of voltage-dependent calcium channel. Immunoreactivity for other channels that may permit calcium influx such as certain ionotropic glutamate receptors and canonical transient receptor potential channels (TRPCs) was similarly absent, although DA-IPC varicosities did show ryanodine receptor immunoreactivity, indicating the presence of intracellular calcium stores. The synaptic vesicle proteins sv2a and sv2b and certain other proteins associated with the presynaptic membrane were absent from DA-IPC varicosities, but the vesicular SNARE protein, vamp2, was present in a fraction of those varicosities. We identified a presumed second class of IPC that is GABAergic but not dopaminergic. Outer retinal varicosities of this putative GABAergic IPC did colocalize synaptic vesicle protein 2a, suggesting they possessed a conventional vesicular release mechanism.

Original languageEnglish
Pages (from-to)158-174
Number of pages17
JournalJournal of Comparative Neurology
Volume510
Issue number2
DOIs
Publication statusPublished - Sep 10 2008

Fingerprint

Retina
Synaptic Vesicles
Tyrosine 3-Monooxygenase
Calcium
Proteins
Vesicular Monoamine Transport Proteins
Transient Receptor Potential Channels
Ionotropic Glutamate Receptors
SNARE Proteins
Ryanodine Receptor Calcium Release Channel
Dopaminergic Neurons
Calcium Channels
Neurotransmitter Agents
Membranes

Keywords

  • Calcium channel
  • Dopamine
  • GABA
  • Immunocytochemistry
  • Presynaptic protein

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Anatomical and neurochemical characterization of dopaminergic interplexiform processes in mouse and rat retinas. / Witkovsky, Paul; Gábriel, R.; Križaj, David.

In: Journal of Comparative Neurology, Vol. 510, No. 2, 10.09.2008, p. 158-174.

Research output: Contribution to journalArticle

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