Suppression of corneal epithelial choline acetyltransferase activity by lid closure

Unilateral lid closure lowered corneal epithelial choline acetyltransferase activity in eyes that grossly and histologically appeared normal. This effect on choline acetyltransferase activity was relatively specific and not the result of a generalized depression of metabolism since thymidine, uridine, leucine, and alanine incorporation rates into corneal epithelium were not significantly altered. Lactic dehydrogenase activity was not depressed. Decreased choline acetyltransferase activity was present 24 hr after lid closure and was maximum by the eighth day of lid closure. Recovery of enzyme activity after re-opening the lids required more than four weeks.