Post-ganglionic chemical sympathectomy of the cat nictitating membrane following systemic epinephrine: degeneration of nerve terminals followed by regeneration.

The present study was designed to provide further evidence that high doses of systemically administered epinephrine can result in a post-ganglionic chemical sympathectomy and to look for evidence of regeneration of nerve terminals. Three days following the systemic administration of a high dose of epinephrine a prolapse of the cat nictitating membrane was observed. Examination of the inferior smooth muscle associated with the membrane revealed ultrastructural evidence of nerve terminal destruction which was associated with a marked depletion of endogenous norepinephrine as measured with a catecholamine radioenzyme assay. Three weeks following treatment, appearance of nerve terminals and endogenous norepinephrine levels in the contralateral nictitating membrane were indistinguishable from untreated controls. High doses of epinephrine appear to result in nerve terminal degeneration, followed by regeneration, similar to that reported following 6-hydroxydopamine.