Protective Effect of Prostaglandin E[sub.1] on Radiation-Induced Proliferative Inhibition and Apoptosis in Keratinocytes and Healing of Radiation-Induced Skin Injury in Rats

We examined the effects of prostaglandin E[sub.1] (PGE[sub.1]) on radiation-induced proliferation inhibition and apoptosis in keratinocytes and healing of radiation-induced skin injury in a rat model. PGE[sub.1] had a protective effect on radiation-induced growth inhibition in keratinocytes in vitro, but not in fibroblasts. Varying concentrations of PGE[sub.1] were subcutaneously administered into the posterior neck region. X-irradiation at a dose of 20 Gy was administrated to the lower part of the back using a lead sheet with two holes 30 min to 1 h before or after the administration of PGE[sub.1]. Although X-irradiation induced epilation, minor erosions, or skin ulcers in almost all rats, PGE[sub.1] administration prior to irradiation reduced these irradiation injuries. Staining with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling showed that proportions of apoptotic keratinocytes in the X-irradiated skin of PGE[sub.1]-administered rats were significantly lower than for those in the skin of rats which did not receive PGE[sub.1]. Cutaneous full-thickness defective wounds were then formed in X-irradiated areas to examine the time course of wound healing. Wound healing was significantly delayed because of X-irradiation, but PGE[sub.1] administration prior to irradiation led to a significantly shorter delay in wound healing compared with controls. Decreasing delay in wound healing was correlated with concentration of PGE[sub.1] administrated. Thus, PGE[sub.1]-administration may potentially alleviate the radiation-induced skin injury. Keywords: Radioprotection, Prostaglandin E[sub.1], Apoptosis, Keratinocytes, Healing-impaired wound