Immunohistochemical localization of dopamine-beta-hydroxylase in human andmonkey eyes

Purpose. To investigate the pattern of dopamine-P-hydroxylase (DBH)-contain ing fibers in human and monkey eyes. Methods. DBH-containing fibers were detected by immunohistochemistry. The p rimary antibody used recognized DBH, the key enzyme in the conversion of do pamine to noradrenaline. Results. In the anterior segment, DBH immunoreaction product was found in t he peripheral corneal endothelium layer, in both the dilator and sphincter muscles of the iris, as well as in the anterior border layer of the iris. T he ciliary muscle and the stroma of the ciliary processes were also zones o f concentration. In the posterior segment, staining was seen around blood v essels in the choroid, in the vascular walls of the short posterior ciliary arteries and in the ciliary nerves. The retina was also immunopositive, wi th specific labeling in cones and rods of photoreceptors, inner and outer p lexiform layers and ganglion cell layer. There was no significant differenc e in the distribution of DBH-related immunoreactivity in human and monkey e yes. Conclusions. The localization of DBH-related immunoreactivity is generally consistent with the known physiological roles of noradrenaline. However, an apparently high concentration of the enzyme in the anterior border layer o f the iris and in retinal photoreceptors raises questions about the possibl e role of DBH-containing fibers in these structures.