Changes in Corneal RNA levels after Denervation of the Trigeminal Nerve.

Abstract

Abstract: : Purpose: To study the change in RNA levels of the cornea after stereotactic denervation of the trigeminal nerve. Methods: Stereotactic surgery with a ventral approach through the soft tissues of the mandible results in excellent localization and precise destruction of the V1/V2 branch(es) of the trigeminal nerve as it exits the trigeminal ganglion. Using radiofrequency thermocautery in 34 rats, the reliability of a destructive lesion of V1/V2 was found to be greater than 87%. Five days later the rats were sacrificed and the corneas were removed, placed in RNAlater, and frozen at –70º C. RNA was extracted from individual corneas and quantitated. The untreated contralateral eye served as the control. Comparisons were made between the treated eye and the untreated eye in the same animal. Results: Of the 34 rats studied, 79% had an increase of RNA greater than the controls when comparing the treated eye vs. the control eye in the same animal. The average increase of RNA was 7–fold higher in the corneas after destruction of the trigeminal nerve compared to the control eye. A student t–test demonstrated p < 0.0003. Conclusions: Stereotactic radiofrequency thermocautery can reliably denervate the trigeminal nerve at the V1/V2 region. This reproducible animal model for denervation of the cornea will result in a significant increase in RNA levels in the cornea seven–fold higher than in the control cornea. RNA levels corroborate the accuracy of the localization of the stereotactic approach for denervation of the cornea. Moreover, the increase in RNA levels in the cornea may be a physiological response to nerve injury or denervation. This observation is being studied in greater detail by this laboratory.

Keywords: cornea: basic science • keratitis