Immunocytochemical localization of neurons containing the AMPA GluR2/3 subunit in the hamster visual cortex.

AMPA glutamate receptors play a crucial role in brain functions such as synaptic plasticity and development. We have studied the chemo-architecture of the AMPA glutamate receptor subtype GluR2/3 in the hamster visual cortex by immunocytochemistry and compared it with the distribution of the calcium-binding proteins, calbindin D28K and calretinin. Anti-GluR2/3-immunoreactive (IR) neurons were predominantly located in layers II/III, V, and VI, and the majority of the labeled neurons were round or oval. However, many pyramidal cells in layer V were also labeled. Two-color immunofluorescence revealed that none of the GluR2/3-IR neurons contained calbindin D28 K or calretinin. Thus specific layers of neurons express the GluR2/3 subunit and these do not correlate with expression of calbindin D28K and calretinin.

The distribution and morphology of calbindin D28K- and calretinin-immunoreactive neurons in the visual cortex of mouse.

We studied the distribution and morphology of calbindin D28K- and calretinin-immunoreactive (IR) neurons in the mouse visual cortex with immunocytochemistry. Most of the calbindin D28K-IR neurons were located in layers II/III and V, while calretinin-IR neurons were predominantly located in layers II/III. The labeled neurons showed variations in morphology. The majority of the calbindin D28K-IR neurons were stellate and round or oval cells with multipolar dendrites. The majority of calretinin-IR neurons were vertical fusiform cells with long processes traveling perpendicular to the pial surface. In the mouse visual cortex, 20.2% of calbindin D28K-IR neurons contained calretinin and 27.2% of calretinin-IR neurons contained calbindin D28K. These results indicate that the calcium-binding proteins, calbindin D28K and calretinin are distributed in specific layers and in selective cell types of the mouse visual cortex.

Changes of calretinin, calbindin D28K and parvalbumin-immunoreactive neurons in the superficial layers of the hamster superior colliculus following monocular enucleation.

We studied the effects of monocular enucleation on the patterned distribution of calretinin-, calbindin D28K- and parvalbumin-immunoreactive (IR) neurons in the superficial layers of the hamster superior colliculus (SC). The calcium-binding proteins were localized using antibody immunocytochemistry. Almost complete depletion of the calretinin-IR fibers in the superficial layers of the contralateral SC was found following unilateral enucleation. Quantitative analysis showed that on the experimental side of the SC, an enormous number of calretinin-IR cells newly appeared (716%). On the experimental side of the SC, the number of parvalbumin-IR cells also increased (32%). By contrast, on the experimental side of the SC, the number of calbindin D28K-IR cells exhibited a reduction (43%). Two-color immunofluorescence revealed that none of the newly appeared calretinin-IR cells were labeled with antibodies to calbindin D28K or parvalbumin. The present results demonstrate that retinal projection may control the activity of the expression of these calcium-binding proteins in the hamster SC but in different manners. The results also show that the patterned change of calretinin and parvalbumin in the hamster SC is comparable with other animals, but the change of calbindin D28K is not identical.

Morphology of calretinin-immunoreactive neurons in the superficial layers of hamster superior colliculus after enucleation: lack of co-localization with GABA.

We recently reported on the distribution and effects of eye enucleation on the immunoreactivity of calretinin in the superficial layers of the hamster superior colliculus (SC). In the present study, we describe the types of labeled cells and compare this labeling to that of GABA, the major inhibitory neurotransmitter in the central nervous system. An almost complete depletion of calretinin-immunoreactive (IR) fibers in the superficial layers of the contralateral SC was found following unilateral enucleation. On the contralateral SC, many calretinin-IR cells were newly appeared. The majority of the newly-appeared cells had small- to medium-sized round, oval, or vertical fusiform cell bodies. Two-color immunofluorescence revealed that none of these newly-appeared cells were labeled with an antibody to GABA. The present results show that the calretinin-IR cells are unique in the superficial hamster SC when compared to most of the other brain areas, where many calretinin-IR cells are GABAergic interneurons.