Jea-Young Lee

Types and density of calretinin-containing retinal ganglion cells in mouse.

Calcium-binding proteins are present in a number of retinal cell types. Types and density of parvalbumin-immunoreactive (IR) retinal ganglion cells (RGCs) in the mouse retina were previously reported using a newly developed single-cell injection technique following immunocytochemistry [Kim, T.J., Jeon, C.J., 2006. Morphological classification of parvalbumin-containing retinal ganglion cells in mouse: single-cell injection after immunocytochemistry. Invest. Ophthalmol. Vis. Sci. 47, 2757-2764]. The present study was aimed at describing the types and density of calretinin-containing RGCs in the mouse. Calretinin-containing RGCs were first identified by immunocytochemistry and were then iontophoretically injected with a lipophilic dye, DiI. Subsequently, confocal microscopy was used to characterize the morphologic classification of the calretinin-IR ganglion cells on the basis of the dendritic field size, branching pattern, and stratification within the inner plexiform layer (IPL). The results indicated that at least 10 morphologically different types of RGCs express calretinin in the mouse retina. They were heterogeneous in morphology: monostratified to bistratfied, small-to-large dendritic field size, and sparse-to-dense dendritic arbors. The present study showed that 86.59% (38,842/44,857) of RGCs contained calretinin. The density of calretinin-IR ganglion cell in the mouse retina was 2795cells/mm(2). The combined approach of cell morphology and the selective expression of a particular protein would provide valuable data for further knowledge on functional features of the RGCs.

AII amacrine cells in the inner nuclear layer of bat retina: identification by parvalbumin immunoreactivity.

The purpose of this investigation is to characterize parvalbumin-immunoreactive (PV-IR) amacrine cells in bat retina through immunocytochemistry, quantitative analysis, and confocal microscopy. PV immunoreactivity was present in ganglion cell and inner nuclear layers. The regular distribution of PV-IR neurons, the inner marginal locations of their cell bodies in the inner nuclear layers, and the distinctive bilaminar morphologies of their dendritic arbors in the inner plexiform layers suggested that these PV-IR cells were AII amacrine cells. PV-IR neurons were double labeled forcalretinin, a marker for AII cells. These results indicate that PV antibodies can be used to label AII cells selectively in bats. The existence of AII cells suggests that bats have retinas involved in both rod-driven and cone-driven signals.

Calcium-binding Protein Calretinin Immunoreactivity in the Dog Superior Colliculus

We studied calretinin-immunoreactive (IR) fibers and cells in the canine superior colliculus (SC) and studied the distribution and effect of enucleation on the distribution of this protein. Localization of calretinin was immunocytochemically observed. A dense plexus of anti-calretinin-IR fibers was found within the upper part of the superficial gray layer (SGL). Almost all of the labeled fibers were small in diameter with few varicosities. The intermediate and deep layers contained many calretinin-IR neurons. Labeled neurons within the intermediate gray layer (IGL) formed clusters in many sections. By contrast, labeled neurons in the deep gray layer (DGL) did not form clusters. Calretinin-IR neurons in the IGL and DGL varied in morphology and included round/oval, vertical fusiform, stellate, and horizontal neurons. Neurons with varicose dendrites were also labeled in the IGL. Most of the labeled neurons were small to medium in size. Monocular enucleation produced an almost complete reduction of calretinin-IR fibers in the SC contralateral to the enucleation. However, many calretinin-IR cells appeared in the contralateral superficial SC. Enucleation appeared to have no effect on the distribution of calretinin-IR neurons in the contralateral intermediate and deep layers of the SC. The calretinin-IR neurons in the superficial dog SC were heterogeneous small- to medium-sized neurons including round/oval, vertical fusiform, stellate, pyriform, and horizontal in shape. Two-color immunofluorescence revealed that no cells in the dog SC expressed both calretinin and GABA. Many horseradish peroxidase (HRP)-labeled retinal ganglion cells were seen after injections into the superficial layers. The vast majority of the double-labeled cells (HRP and calretinin) were small cells. The present results indicate that antibody to calretinin labels subpopulations of neurons in the dog SC, which do not express GABA. The results also suggest that the calretinin-IR afferents in the superficial layers of the dog SC originate from small class retinal ganglion cells. The expression of calretinin might be changed by the cellular activity of selective superficial collicular neurons. These results are valuable in delineating the basic neurochemical architecture of the dog visual system.

Synaptic pattern of AMPA receptor subtypes upon direction-selective retinal ganglion cells

In the search for anisotropies that might contribute to a directional preference of direction-selective (DS) retinal ganglion cells (RGCs), we studied the distributions of AMPA receptor subtypes GluR1, GluR2/3, and GluR4 upon the dendritic arbors of DS RGCs of the rabbit with antibody immunocytochemistry. DS RGCs were injected with Lucifer yellow and the cells were identified by their characteristic morphology. The double-labeled images of dendrites and receptors were visualized by confocal microscopy and were reconstructed from high-resolution confocal images. We found no evidence of asymmetry in any of the AMPA receptor subunits examined upon the dendritic arbors of both On and Off layers of DS RGCs. The present results indicate that direction selectivity appears to lie in presynaptic pattern.

Organization of Calbindin D28K-Immunoreactive Neurons in the Dog Superior Colliculus

Abstract We localized calbindin D28K-immunoreactive (IR) neurons in the superior colliculus (SC) of the dog and studied the distribution and effect of enucleation on the distribution of this protein. We also compared this labeling to that of GABA. Calbindin D28K was localized with antibody immunocytochemistry. Calbindin D28K-IR neurons formed three laminar tiers in the SC, one within the lower superficial gray layer (SGL), the second within the upper intermediate gray layers (IGL), and the third within the deep gray layer (DGL). The third tier was not very distinctive when compared with the other two tiers. Calbindin D28K-IR neurons in the SC varied dramatically in morphology and size, and included round/oval, vertical fusiform, stellate, pyriform, and horizontal neurons. Neurons with varicose dendrite were also labeled in the IGL. Enucleation appeared to have no effect on the distribution of calbindin D28K-IR neurons in the contralateral SC. Two-color immunofluorescence revealed that a small percentage (11.20%) of calbindin D28K-IR neurons co-localized with GABA. The current results demonstrate that the patterned distribution of calbindin D28K-IR neurons in the intermediate and deep SC is comparable with other animals, but that the distribution of this protein in the superficial SC is strikingly different from that in previously studied animals. The results also suggest that retinal projection may not control the activity of the expression of calbindin D28K in the dog SC. These results will not only provide valuable knowledge of the basic neurochemical architecture of the dog visual system, but also provide clues for the understanding of the similarities and differences among species.

Immunocytochemical Localization of Calcium-binding Proteins, Calbindin D28K-, Calretinin-, and Parvalbumin-containing Neurons in the Dog Visual Cortex

Although the dog is widely used to analyze the function of the brain, it is not known whether the distribution of calcium-binding proteins reflects a specific pattern in the visual cortex. The distribution of neurons containing calcium-binding proteins, calbindin D28K, calretinin, and parvalbumin in adult dog visual cortex were studied using immunocytochemistry. We also compared this labeling to that of gamma-aminobutyric acid (GABA). Calbindin D28K-immunoreactive (IR) neurons were predominantly located in layer II/III. Calretinin- and parvalbumin-IR neurons were located throughout the layers with the highest density in layers II/III and IV. The large majority of calbindin D28K-IR neurons were multipolar stellate cells. The majority of the calretinin-IR neurons were vertical fusiform cells with long processes traveling perpendicular to the pial surface. And the large majority of parvalbumin-IR neurons were multipolar stellate and round/oval cells. More than 90% of the calretinin- and parvalbumin-IR neurons were double-labeled with GABA, while approximately 66% of the calbindin D28K-IR neurons contained GABA. This study elucidates the neurochemical structure of calcium-binding proteins. These data will be informative in appreciating the functional significance of different laminar distributions of calcium-binding proteins between species and the differential vulnerability of calcium-binding proteins-containing neurons, with regard to calcium-dependent excitotoxic procedures.

Glutamate Receptors GluR1 and GluR4 in the Hamster Superior Colliculus: Distribution and Co-localization with Calcium-Binding Proteins and GABA

We investigated the distributions of AMPA glutamate receptor subtypes GluR1 and GluR4 in the hamster superior colliculus (SC) with antibody immunocytochemistry and the effect of enucleation on these distributions. We compared these labelings to those of GluR2/3 in our previous report (Park et al., 2004, Neurosci Res., 49:139–155) and calcium-binding proteins calbindin D28K, calretinin, parvalbumin, and GABA. Anti-GluR1-immunoreactive (IR) cells were scattered throughout the SC. By contrast, anti-GluR4-IR cells formed distinct clusters within the lower lateral stratum griseum intermediale (SGI) and lateral stratum album intermediale (SAI). The GluR1- and GluR4-IR neurons varied in size and morphology. The average diameter of the GluR1-IR cells was 13.00 µm, while the GluR4-IR cells was 20.00 µm. The large majority of IR neurons were round or oval cells, but they also included stellate, vertical fusiform and horizontal cells. Monocular enucleation appeared to have no effect on the GluR1 and GluR4 immunoreactivity. Some GluR1-IR cells expressed calbindin D28K (9.50%), calretinin (6.59%), parvalbumin (2.53%), and GABA (20.54%). By contrast, no GluR4-IR cells expressed calcium-binding proteins or GABA. Although the function of the AMPA receptor subunits in SC is not yet clear, the distinct segregation of the GluR subunits, its differential colocalization with calcium-binding proteins and GABA, and differential responses to enucleation suggest the functional diversity of the receptor subunits in visuo-motor integration in the SC.

Parvalbumin-Immunoreactive Cells in the Superior Colliculus in Dog: Distribution, Colocalization with GABA, and Effect of Monocular Enucleation

Parvalbumin (PV) is thought to play a major role in buffering intracellular calcium. We studied the distribution, morphology of PV-immunoreactive (IR) cells, and the effect of enucleation on the PV distribution in the superior colliculus (SC) in dog (Canis familiaris) and compared PV labeling to that of calbindin D28K (CB) and GABA. These cells formed three laminar tiers in the dog SC; 1) the upper superficial gray layer (SGL), 2) the lower optic layer (OL) and the upper intermediate gray layer, and 3) the deep layer. The third tier was not very distinct when compared with the other two tiers. The distribution of PV-IR cells is thus complementary to that of CB-IR tiers. Our present data on the distribution of PV-IR cells within the superficial layers are strikingly different from those in previously studied mammals, which show PV-IR cells within the lower SGL and upper OL. However, there were no distinct differences in distribution within the deep layers compared with that of previously studied mammals. PV-IR cells in the SC varied dramatically in morphology and size, and included round/oval, vertical fusiform, stellate, horizontal and pyriform cells. Two-color immunofluorescence revealed quantitatively that 11.67% of the PV-IR cells colocalized with GABA. Monocular enucleation appeared to have no effect on the distribution of PV-IR cells in the contralateral SC. Similar to CB, these data suggest that retinal projection may not control the expression of PV in the dog SC. These results provide important information for delineating similarities and differences in the neurochemical architecture of the visual system.

Retrograde Tracer Studies of Tecto-Reticulospinal Pathway and Dorsal Lateral Geniculate Nucleus on GluR1- and GluR4-Immunoreactive Neurons in the Hamster Superior Colliculus

We recently reported the distributions of AMPA (α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate) receptor subtypes glutamate receptors (GluR) 1 and GluR4 in the superior colliculi (SC) of hamsters with antibody immunocytochemistry and the effect of enucleation on these distributions. We also compared these labelings to those of calcium-binding proteins calbindin D28K, calretinin, parvalbumin, and GABA. In the present study, we investigated whether the GluR1- and GluR4-immunoreactive (IR) neurons are interneurons or projection neurons by injection of the retrograde tracer horseradish peroxidase (HRP) into one of each major ascending and descending pathways of the SC. HRP injections were made into a tecto-reticulospinal pathway (TRS) and dorsal lateral geniculate nucleus (dLGN). Animals were then allowed to recover and to survive for 48 hr before perfusion. Sections containing retrograde-labeled neurons were then treated for GluR-immunoreactivity. HRP injections proved that only a small population of the GluR1-IR cells project into TRS (1.4%) and dLGN (2.6%). However, a large subpopulation of GluR4-IR cells project into TRS (32.7%). The differential compositions of inter/projection neurons, along with our previous studies on the separate distribution of the GluR subunits, its differential co-localization with calcium-binding proteins and GABA, and differential reactions to enucleations, strongly imply the functional variety of the receptor subunits in visual behavior responses.