Effect of sensory and sympathetic denervation on substance P immunoreactivity in nerve fibres of the rabbit eye

Substance P (SP) immunoreactivity was demonstrated in ocular tissues of rabbit. SP was found in nerve fibres of cornea iris, ciliary body, choroid and in the inner plexiform layer of the retina.In order to verify the origin of these nerves the animals were subjected to two different denervation procedures: intracranial combined maxillary and ophthalmic neurotomy or superior cervical ganglionectomy. The former operation destroyed all SP immunoreactive nerves of the ipsilateral eye except for the retina, whereas the latter had no effect. It is concluded that the ocular SP immunoreactive nerves are sensory trigeminal fibres. SP immunoreactivity in the retina is not due to sensory nerves but probably to amacrine cells.