Differential distribution of hyperpolarization-activated and cyclic nucleotide-gated channels in cone bipolar cells of the rat retina.

The hyperpolarization-activated and cyclic nucleotide-gated (HCN) channel isoforms HCN1, HCN2, and HCN4 were localized by immunofluorescence in the rat retina. Double labeling with the vesicular glutamate transporter (VGLUT1) was used to identify bipolar cell axon terminals in the inner retina. The HCN1 channel was localized to two cell types with differing intracellular distributions, insofar as staining was seen in the dendrites of a putative OFF-type cone bipolar cell and in the axon terminals of an ON-type bipolar that ramifies in stratum 3 (s3) of the inner plexiform layer (IPL).

Differential cellular and subcellular distribution of glutamate transporters in the cat retina.

Retrieval of glutamate from extracellular sites in the retina involves at least five excitatory amino acid transporters. Immunocytochemical analysis of the cat retina indicates that each of these transporters exhibits a selective distribution which may reflect its specific function. The uptake of glutamate into Muller cells or astrocytes appears to depend upon GLAST and EAAT4, respectively.

Immunocytochemical localization of three vesicular glutamate transporters in the cat retina.

Vesicular transporters play an essential role in the packaging of glutamate for synaptic release and so are of particular importance in the retina, where glutamate serves as the neurotransmitter for photoreceptors, bipolar cells, and ganglion cells. In the present study, we have examined the distribution of the three known isoforms of vesicular glutamate transporter (VGLUT) in the cat retina. VGLUT1 was localized to all photoreceptor and bipolar cells, whereas VGLUT2 was found in ganglion cells.

Metabolic mapping in mammalian retina: a biochemical and 3H-2-deoxyglucose autoradiographic study.

It has long been known that mammalian retinas metabolize glucose aerobically to lactic acid and carbon dioxide. The classical view holds that glucose is the primary substrate for energy metabolism in all retinal cells, and that photoreceptor cells have the highest rates of glycolysis and respiration. A different and more recent view is that the Müller cells are the principal, if not sole aerobic producers of lactate, which then serves as the primary fuel for the mitochondria in photoreceptor cells and other retinal neurons.

Identification of a cone bipolar cell in cat retina which has input from both rod and cone photoreceptors.

It has been generally accepted that rod photoreceptor cells in the mammalian retina make synaptic contact with only a single population of rod bipolar cells, whereas cone photoreceptors contact a variety of cone bipolar cells. This assumption has been challenged in rodents by reports of a type of cone bipolar cell which receives input from both rods and cones. Questions remained as to whether similar pathways are present in other mammals.

Distribution of protein kinase C isoforms in the cat retina.

Immunocytochemical localization was carried out for five isoforms of protein kinase C (PKC) in the cat retina. In common with other mammalian species, PKCalpha was found in rod bipolar cells. Staining was also seen in a small population of cone bipolar cells with axon terminals ramifying near the middle of the inner plexiform layer (IPL).

Agonist-stimulated cobalt uptake provides selective visualization of neurons expressing AMPA- or kainate-type glutamate receptors in the retina.

Fast-acting excitatory neurotransmission in the retina is mediated primarily by glutamate, acting at alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) -selective and kainate-selective receptors. To localize these sites of action, cat retinas were stimulated with either AMPA or kainate and processed for histochemical visualization of cobalt uptake through calcium-permeable channels. Treatment with both agonists resulted in staining of A- and B-type horizontal cells and several types of OFF cone bipolar cells; there was no evidence for staining of ON cone bipolar cells or rod bipolar cells.

Cellular and subcellular distribution of NMDA receptor subunit NR2B in the retina.

Immunocytochemical studies showed the presence of staining for the N-methyl-D-aspartate (NMDA)-R2B glutamate receptor subunit at multiple sites in the cat retina. Reaction product in photoreceptor cells was localized at the inner/outer segment junction and in the axon terminals. Staining within the inner retina was limited to ganglion cells and their dendrites ramifying throughout the inner plexiform layer.

Immunocytochemical localization of kainate-selective glutamate receptor subunits GluR5, GluR6, and GluR7 in the cat retina.

Localizations of the kainate-selective glutamate receptor subunits GluR5, 6, and 7 were studied in the cat retina by light and electron microscopic immunocytochemistry. GluR5 immunoreactivity was observed in the cell bodies and dendrites of numerous cone bipolar cells and ganglion cells. The labeled cone bipolar cells make basal or flat contacts with cone pedicles in the outer plexiform layer, leading to their identification as OFF-center bipolar cells.

AMPA-selective glutamate receptor subunits GluR2 and GluR4 in the cat retina: an immunocytochemical study.

AMPA-selective glutamate receptors play a major role in glutamatergic neurotransmission in the retina and are expressed in a variety of neuronal subpopulations. In the present study, immunocytochemical techniques were used to visualize the distribution of GluR2 and GluR4 subunits in the cat retina. Results were compared with previous localizations of GluR1 and GluR2/3.

Transmitter-specific input to OFF-alpha ganglion cells in the cat retina.

The synaptic input to OFF-center alpha ganglion cells in the cat retina was analyzed by electron microscopic reconstruction to quantify the bipolar and amacrine cell input and to determine the neurotransmitter content of the presynaptic cells. Cone bipolar cells were found to comprise 11% of the total input with their dyad synapses distributed across the dendritic tree. The remaining contacts were conventional synapses indicative of amacrine cells; postembedding immunogold labeling was used to characterize these cells as either GABA- or glycine-immunoreactive.

Localization of metabotropic glutamate receptors mGluR1alpha and mGluR2/3 in the cat retina.

The distribution of metabotropic glutamate receptors 1alpha (mGluR1alpha) and mGluR2/3 in the cat retina was studied through the use of preembedding immunocytochemistry for light and electron microscopy. Staining for mGluR1alpha in the outer plexiform layer was seen in numerous punctate structures that were identified as rod spherules. Cone pedicles remained unlabeled.

Localization of AMPA-selective glutamate receptor subunits in the cat retina: a light- and electron-microscopic study.

The distribution of AMPA-selective glutamate receptor subunits was studied in the cat retina using antisera against GluR1 and GluR2/3. Both antisera were localized in postsynaptic sites in the outer plexiform layer (OPL) as well as the inner plexiform layer (IPL). Immunoreactivity for GluR1 was seen in a subpopulation of OFF cone bipolar cells and a number of amacrine and ganglion cells.

Calretinin in the cat retina: colocalizations with other calcium-binding proteins, GABA and glycine.

Immunocytochemical techniques were used to determine the distribution of the calcium-binding protein calretinin in the cat retina. Comparisons were made with parvalbumin and calbindin as well as with the inhibitory neurotransmitters GABA and glycine. Calretinin immunoreactivity was seen in horizontal cells and multiple subpopulations of amacrine and ganglion cells.

Plasma membrane calcium ATPase in synaptic terminals of chick Edinger-Westphal neurons.

The plasma membrane calcium ATPase pump (PMCA) is one of two major mechanisms known to be involved in extruding calcium from cells. The monoclonal antibody 5F10 was used to examine the distribution of PMCA in chick Edinger-Westphal neurons, a population of cholinergic preganglionic neurons whose cells bodies reside in the Edinger-Westphal nucleus in the brainstem and whose axons form synaptic terminals on parasympathetic neurons in the ciliary ganglion. Definitive PMCA immunoreactivity was undetectable in Edinger-Westphal cell bodies in the brainstem.

Neurotransmitters in the retina.

Processing of visual information within the retina depends in large measure upon a complement of chemical neurotransmitters which are released at synaptic contacts between individual neurons. Numerous investigators have participated in the identification of many of these transmitters and their assignment to specific neuronal subpopulations. However, it is now clear that the action of each transmitter depends upon the receptor molecules to which it binds.

Morphological diversity in terminals of W-type retinal ganglion cells at projection sites in cat brain.

The morphological features of retinal terminals in cat brain were examined at sites where projections of W-type ganglion cells predominate. These included the parvicellular C laminae of the dorsal lateral geniculate nucleus, the ventral lateral geniculate nucleus, stratum griseum superficiale of the superior colliculus, and the suprachiasmatic nucleus. Positive identification of retinal terminals was achieved following anterograde transport of intravitreally injected native or wheat germ agglutinin-conjugated horseradish peroxidase.

Distribution of AMPA-selective glutamate receptor subunits in the cat retina.

Immunocytochemical techniques were used to localize AMPA-selective glutamate receptor subunits in the cat retina. The antisera employed recognize GluR1, GluR2/3 or GluR4 subunits. Each antiserum produced a distinctive staining pattern which included horizontal cells, cone bipolar cells, and amacrine and ganglion cells.

Glutamate immunoreactivity in the cat retina: a quantitative study.

Immunocytochemical methods were used to visualize glutamate immunoreactivity in the cat retina and to compare its localization with that of aspartate, GABA, and glycine. The cellular and subcellular distribution of glutamate was analyzed at the light-microscopic level by optical densitometry and at the electron-microscopic level by immunogold quantification. The findings were consistent with the proposed role for glutamate as the neurotransmitter of photoreceptors and bipolar cells as particularly high concentrations of staining were found in synaptic terminals of these cells.

Morphological diversity and glutamate immunoreactivity of retinal terminals in the suprachiasmatic nucleus of the cat.

Although the cat visual system has been the subject of intensive investigation, little attention has been given to the morphological features of ganglion cell projections to the suprachiasmatic nucleus. The present study has utilized anterograde transport of horseradish peroxidase and wheat germ agglutinin-conjugated horseradish peroxidase to label ganglion cell terminals in the cat suprachiasmatic nucleus. Visualization of the reaction product was facilitated through the use of gold-substituted silver intensification.

Kainate elicits elevated nuclear calcium signals in retinal neurons via calcium-induced calcium release.

Intracellular Ca2+ was imaged in cultured neonatal rat retinal neurons using the Ca(2+)-sensitive dye fluo-3 and confocal scanning laser microscopy. Depolarization via elevation of bath K+ concentration resulted in large cytoplasmic and nuclear Ca2+ signals; responses in the nucleus exceeded those of the cytoplasm. Glutamate or kainate application elicited the same intracellular pattern of elevated Ca2+ signals.

Immunocytochemical evidence for the involvement of glycine in sensory centers of the rat brain.

Glycine-like immunoreactivity was localized to a number of sites in the rat brain which are involved in processing sensory information. In the auditory and vestibular systems, glycine immunoreactivity was seen in dorsal and ventral cochlear nuclei, superior olive, trapezoid body, medial and lateral vestibular nuclei, and inferior colliculus. Staining in the visual system was seen in retina, dorsal lateral geniculate nucleus, and superior colliculus.

Hydrolysis of substance P in the rabbit retina: II. The role of a membrane-associated acetylcholine-sensitive metalloendopeptidase. An in vitro study.

Studies in the rabbit retina have shown that infusion of exogenous acetylcholine (ACh) into the vitreal chamber leads to an increase in the amount of substance P (SP) immunoreactivity (Goebel and Pourcho, submitted). This increase was determined to be independent of new peptide synthesis, suggesting that the elevated level of SP is the result of ACh inhibition of an SP-degrading protease. This phenomenon has now been confirmed in vitro in both tissue slice and retinal homogenate assays.

Hydrolysis of substance P in the rabbit retina: I. Involvement of acetylcholine and acetylcholinesterase. An in vivo study.

The laminar patterns of acetylcholinesterase (AChE) activity and substance P (SP) immunoreactivity within the inner plexiform layer (IPL) of the rabbit retina show striking similarities. Discrete bands of SP-immunoreactivity were seen at 1-7%, 40-48% and 85-95% depth of IPL. AChE activity was present throughout the entire thickness of the IPL with moderately stained bands in each sublamina (3-24% in sublamina a and 62-89% in sublamina b depth IPL).

The peptide VIP is a neurotransmitter in rat adrenal medulla: physiological role in controlling catecholamine secretion.

1. The perfused adrenal gland of the rat was used to establish the identity of a non-cholinergic substance involved in splanchnic nerve-mediated secretion of catecholamines. 2.