Aim: To examine the distribution of melatonin 1a (MT1) receptors in the human eye.
Methods: Seven normal human eyes were examined by immunohistochemical staining of paraffin sections, using an anti-MT1 primary antibody and an ABC detection system.
Results: MT1 receptor immunoreactivity (MT1-IR) was detected primarily in the inner segments of rods and cones and in retinal ganglion cells. In addition, MT1-IR was present in the adventitia of retinal arteries and veins, including the papillary region, but absent in ciliary and choroidal vessels. Mild staining of corneal endothelial cells and keratocytes was observed in all but two eyes.
Conclusion: MT1-IR is present in various ocular tissues with the highest density in photoreceptor cells and ganglion cells. The physiological function of these receptors deserves further investigation.