Objective: 

The glutamate NMDA (N-methyl-D-aspartate) receptors are widely distributed in the central nervous system (CNS) where they are involved in many cognitive processes as memory and learning, in motor control etc. In retina, which may be regarded as a biological model of CNS, glutamatergic neurotransmission mediated by NMDA receptors is extensively studied. However, data mainly concerns mammalian retinas, while the lower vertebrate ones are poorly studied. To the largest extent it is true for NMDA receptor subunits NR2C and NR2D which possess special features different from the features of other subunits. That's why the aim of the present study was to investigate their possible distribution in the mixed retina of frog Rana ridibunda and the cone retina of turtle Emis orbicularis.

Methods: 

The indirect immunofluorescent method was used.

Results: 

The NR2C and NR2D immunoreactivities had similar patterns of staining, both to each other and in the two types of retinas. Bright immunofluorescence was present in all retinal layers. In the inner nuclear layer the cell bodies of Müller cells, the main gial cells in retina, were evident. Their processes directed to both plexiform layers could also be followed. The inner and the outer limiting membranes were stained as well. No synaptic staining for these subunits was revealed.

Conclusions: 

The pattern of staining, which is indicative for the Müller cells, shows that retinal glia possesses NMDA receptors containing NR2C and NR2D subunits. A conclusion could be drawn that the retinal glial NMDA receptors differ in their subunits composition from the neuronal NMDA receptors which may be important for the neuron-glia interactions.