It has not been verified whether allopurinol application is beneficial in decreasing the severity of radiation-induced oral mucositis and dermatitis. Rats were divided into 4 groups and received 15 Gy irradiation on the left whisker pad. Group 1 received only irradiation. Group 2 was maintained by applying allopurinol/carrageenan-mixed gel (allopurinol gel) continuously from 2 days before to 20 days after irradiation. Group 3 had allopurinol gel applied for 20 days after radiation. Group 4 was maintained by applying carrageenan gel continuously from 2 days before to 20 days after irradiation. The intra oral mucosal and acute skin reactions were assessed daily using mucositis and skin score systems. The escape thresholds for mechanical stimulation to the left whisker pad were measured daily. In addition, the irradiated tissues at the endpoint of this study were compared with naïve tissue. Escape threshold in group 2 was significantly higher than that in group 1, and mucositis and skin scores were much improved compared with those of group 1. Concerning escape threshold, mucositis and skin scores in group 3 began to improve 10 days after irradiation. Group 4 showed severe symptoms of mucositis and dermatitis to the same extent as that observed in group 1. In the histophathological study, the tissues of group 1 showed severe inflammatory reactions, compared with those of group 2. These results suggest that allopurinol gel application can mitigate inflammation reactions associated with radiation-induced oral mucositis and dermatitis.

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Summary:We histochemically investigated the radioprotection of organelle in acinus on the submandibular gland using amifostine. Mice were divided into those without amifostine administration or irradiation (group A), with amifostine administration and without irradiation (group B), without amifostine and with 5 Gy of irradiation (group C), and with amifostine and 5 Gy of irradiation (group D). In groups B and D were given 100 mg/kg of amifostine at 30 minutes prior to irradiation to the area equivalent to the submandibular gland. HE staining revealed that group D showed atrophy of the acinar cells, though the change was milder than that seen in group C. In AZAN-Mallory staining, fibrogenesis were found more often in group C as compared to the other groups. In Light Microscopic Autoradiography findings, the ratio of reduced silver particles in the acinar cells was lower in group C than in the other groups at 30 minutes after RI administration. Microstructure findings showed the findings were very similar to those of group A. In Electron microscopic Autoradiography, the ratio among the secretory granules was lower in group C at 120 minutes after RI administration. Our results indicate that amifostine can alleviate xerostomia caused by late effect from radiation.

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