Immunocytochemistry of mouse and human retina with antisera to insulin and S-100 protein

Immunocytochemistry using peroxidase antiperoxidase (PAP) techniques showed insulin-like immunoreactivity in the human retina, and in the mouse retina and optic nerve. The immunoreaction product was seen in the inner nuclear, ganglion cell, outer and inner plexiform layers of the retinas, and in glial cell bodies of the optic nerve. A similar staining pattern using antiserum to S-100 protein, a marker for glial elements, was also seen in these tissues. This demonstrates that insulin or insulin-like immunoreactivity appears to be limited to glial cells of the retina and optic nerve. Our study suggests that the presence of insulin or a similar peptide in retina and optic nerve may be important for their normal function and metabolism.