Different forms of the neurotrophin receptor <i>Trk</i>B mRNA predominate in rat retina and optic nerve

Abstract

Abstract The expression of Trk B mRNAs was investigated in rat retina and optic nerve. A 11.5 kb transcript that encodes full‐length TRK B was found to predominate in Northern blots of retinal RNA. By in situ hybridization, this trk B expression was concentrated in the ganglion cell and inner nuclear layers. Furthermore, an antibody to the full‐length TRK B immunostained retinal ganglion cells and their axons. In contrast, Northern blots of optic nerve RNA showed a prominent 9.5 kb band that encoded a form of the TRK B receptor lacking the tyrosine kinase domain. This species was also detected in both the sciatic nerve and cultured astrocytes and C6 glioma cells. These results suggest that neurons express the full‐length TRK B containing the tyrosine kinase domain, while non‐neuronal cells express the truncated form of the receptor. These two classes of TRK B may mediate different neurotrophic actions in the retina and optic nerve. © 1993 John Wiley &amp; Sons, Inc.