Increase in SP-like immunoreactivity in nerve fibres of rabbit iris and ciliary body one to four months following sympathetic denervation.

Substance P (SP) levels in rabbit iris-ciliary body preparations were found to be significantly elevated 30 days after removal of the superior cervical ganglion when compared with the contralateral unoperated side. These elevated levels were still apparent after two and three months. Immunohistochemical studies, using a monoclonal antibody to SP, revealed an increase in the density of SP-immunoreactive nerve fibres in the region of the iris dilator muscle and in the ciliary processes one to four months after sympathectomy, although the density of these fibres in other regions of the iris was not altered.