Substance P immunoreactive sensory nerves supply the rat iris and cornea

The presence, distribution and origin of substance P immunoreactive axons in the rat iris and cornea were investigated in whole mount preparations. A dense network of substance P immunoreactive axons was found throughout the iris but not in the ciliary body. In the cornea, substance P immunoreactive axons were found in the substantia propria, in the subepithelial layer and in the corneal epithelium. Following electrocoagulation of the ophthalmic nerve, most of the substance P immunoreactive axons in the iris and cornea disappeared. No changes in the substance P immunoreactive axons occurred after removal of the superior cervical ganglion. It is concluded that the iris and the cornea are supplied by sensory nerves containing substance P immunoreactivity.