Immunohistochemical localization of the tyrosine kinase receptor TRKB in monkey photoreceptors

Purpose. Given that brain-derived neurotrophic factor (BDNF) is known to rescue photoreceptors in animal models of retinal degeneration, we searched for the expression of the tyrosine kinase receptor trkB in monkey photoreceptors. Methods. Retinas from both eyes of two adult monkeys (N=4) were examined. Sections including the foveas of each eye were mildly fixed in 4% paraformaldehyde for four hours and processed into paraffin. Serial longitudinal sections measuring seven microns in thickness were collected onto slides and stained by the streptavidin-biotin peroxidase technique using an antibody to the gp!45 (full length) trkB receptor (Santa Cruz Biotech, Santa Cruz, CA). Resists, Staining for trkB was localized to cone axons, and was more intense at the pedicles. In the foveal regions, most cone axons and pedicles stained positively for trkB. Peripherally, the staining pattern for trkB was more uniform. No staining of the photoreceplor outer segments was seen. Further characterization with conespecific antibodies will determine whether there are differences in trkB expression between different cone subtypes. Conclusions. TrkB receptor is expressed by photoreceptors in monkey retinas, and is noted primarily in the axons and pedicles of cones. This may aid in understanding the mechanism of neurotrophin rescue of photoreceptors damaged in experimental retinal degenerations.

Duke Scholars

Author Stuart James McKinnon Ophthalmology, Glaucoma