Changes in the rate of epithelial proliferation of rat oral mucosa in response to acute inflammation induced by turpentine

Abstract

Inflammatory lesions were produced in the buccal mucosa by a subepithelial injection of turpentine; animals were killed 24 h later, 1 h after an intravenous injection of tritiated thymidine ([ 3H]-Tdr). Control rats were given [ 3H]-Tdr but no turpentine. Lesions comprised a turpentine pool surrounded by a dense layer of inflammatory cells, beyond which the tissues were more diffusely inflamed. The labelling index (L.I.) for mitotic activity in overlying epithelium was determined in a region (C) close to the layer of dense infiltration and in a region (D) more distant. The L.I. in region D was over four times greater than in region C, and nearly four times greater than that of the contralateral, uninjected cheek. The L.I. in the uninjected cheek was significantly lower than that in controls, which may indicate a systemic depression of proliferative activity in the experimental animals, probably due to stress. Thus mild inflammatory injury stimulates epithelial proliferation, whereas more severe inflammation depresses it, perhaps due to more extensive progenitor-cell damage.