Rat retinal Müller cells express Thy-1 following neuronal cell death

In the normal rat retina the Thy-1 antigen is a specific marker of ganglion cells, but degeneration of ganglion cells in vivo does not remove completely the expression of Thy-1 in the retina. To reconcile these differences we have postulated that ganglion cell death could induce a glial response including the expression of Thy-1 in Müller cells, the main glial cell type in the retina. Using immunocytochemistry, we have shown that pure cultures of Müller cells were strongly labelled with antibodies against Thy-1. PCR amplification of cDNA reverse transcribed from Müller cell RNA indicated the presence of Thy-1 transcripts. Double labelling experiments with anti-Thy1 and anti-glutamine synthetase, a marker of Müller cells, indicated the presence of both antigens in the same cells. Although Müller cells expressed Thy-1 mRNA and protein when cultured in the absence of neuronal cells, when co-cultured with retinal neurons they were not labelled with antibodies against Thy-1. Our results suggest that Thy-1 is expressed by Müller cells following loss of retinal neurons. Thy-1 may have an important function during glial response to neuron death in retina.