Cytologic and metabolic effects of prostaglandins on rat skin

The cellular and metabolic effects of exogenous prostaglandins E1, E2, and F2alpha (PGE1, PGE2, and PGF2alpha) were studied in the skin of rats by using scintillation counting, autoradiography, electron microscopy, and scanning electron microscopy. Radioactivity measurements demonstrated that prostaglandins of the E series induced a marked increase in the incorporation of [3H]leucine, [3H]thymidine, [3H]uridine, and [3H]proline in the rat skin, mostly at 1 hr, whereas PGF2alpha inhibited this phenomenon. Light microscopic autoradiography revealed an increased incorporation of [3H]leucine in the cytoplasm of hyperplastic epidermis of PGE-treated rats; also, the incorporation of [3H]thymidine, [3H]uridine, and [3H]proline was significantly increased over the epidermal nuclei, nucleoli, and the collagen fibers of PGE-treated rats. Electron microscopy revealed ultrastructural changes of the epidermal cells and fibroblasts following PGE administration, including an increase in polyribosomes, endoplasmic reticulum, keratohyaline granules, and enlarged intercellular spaces; PGF2alpha induced advanced cytolysis and cell disintegration, with increased lysosome formation. Scanning electron microscopy showed hypertrophied collagen fibers in PGE-treated rats; however, a disruption and disintegration of collagen fibers occurred in PGF2alpha-treated rats. The level of PGE1 in the skin of treated rats was markedly elevated as compared to those of controls. These findings demonstrate that prostaglandins are potent regulators for the epidermal cell ultrastructure and metabolism as well as for collagen synthesis.