Method: 9-week-old female C3H/HeN mice were irradiated with fractionated (6 Gy for 5 days or 7 Gy for 5 days). Mice were irradiated once per day. After final irradiation, PHP sheet was administered into tongue base once per day for 5 days. The extent of damage due to the ulcer formation and tissue erosion stained with toluidine blue were measured with Image J and performed histopathological examination of the midline of tongue. The oral moisture was measured with a moisture checker. The mice were divided into three groups as the non-irradiated group (control), PHP non-administered group (PHP (-)), and PHP administered (PHP (+)) with 10 mice in each groups.
Result: Damaged area in PHP (+) was small compared to PHP (-). Cell infiltration and epithelial hyperplasia were observed in 6 Gy irradiated groups by histopathological examination. Inflammatory response of PHP (+) was weak compared to PHP (-). The ulceration was observed in PHP (-), but not observed in PHP (+) with a dose of 7 Gy. The oral moisture of the tongue was decreased to 27% of control in irradiated groups 7 days after first irradiation, increased to 50% of control in PHP (+) and decreased to 20% of control in PHP (-) at 10 days after first irradiation with doses of 6 Gy and 7 Gy.
Conclusion: These results suggest that PHP have cytoprotective effect on epithelia in radiation disorder and restore the oral moisture. PHP is useful for radiation mucositis and oral disorder.