Effects of chronic sympathetic stimulation on corneal wound healing

To explore the possibility that adrenergic fibers influence epithelial wound healing in the rabbit cornea, chronic electrodes were implanted in the left cervical sympathetic nerve, and symmetrical wounds were produced on the corneal epithelium of both eyes by means of n-heptanol. Continuous sympathetic stimulation was applied to awake, unrestrained animals during the wound-healing process (2-3 days) by use of a portable stimulator that delivered 1 ms, 3-Hz electric pulses at an amplitude necessary to evoke mydriasis. Migration rates of epithelial cells surrounding the wound and estimated wound closure times were calculated by measuring the reduction in wound size. In stimulated corneas, the epithelial migration rate was smaller (36.9 +/- 6.2 microns/hr) than in control corneas (49.4 +/- 5.4 microns/hr), the differences being significant (P < 0.05). Significant differences in wound closure times between stimulated (53.2 +/- 6.8 hr) and control (41.3 +/- 5.5 hr) corneas were also observed. These results suggest a modulatory influence of corneal adrenergic fibers on the processes that follow epithelial injury of the cornea.