Subcutaneous or topical administration of 16,16 dimethyl prostaglandin E2 protects from radiation-induced alopecia in mice.

Alopecia, a common sequel of radiation treatment of brain tumors, increases patient stress to the extent that refusal of treatment may occur. The expectation that loss of hair will be prevented, or that regrowth will occur, is extremely important to patients. To investigate prostaglandin-induced radiation protection against alopecia, the hair of B6D2F1 male mice was plucked from the right thigh and surrounding area to induce anagen. Fourteen days later, mice were injected subcutaneously in the neck with 10 micrograms 16,16 dm PGE2 in 0.2 ml of vehicle, or with the vehicle alone. In another group of previously plucked mice, 16,16 dm PGE2 in the same concentration, or the vehicle was applied topically. One hour later, graded single doses from 6.5 to 12.5 Gy 137Cs gamma irradiation were given to groups of six animals. On day 21 post-plucking, all animals were killed and a portion of the irradiated site was excised. The average hair counts per field in irradiated animals were 85 +/- 4 (6.5 Gy), 25 +/- 5 (8.5 Gy), and 5.5 +/- 0.7 (10 Gy). Animals receiving the prostaglandin systemically had values of 60 +/- 10 (6.5 Gy), 54 +/- 3 (8.5 Gy), 66 +/- 6 (10 Gy), and 30.1 +/- 8 (12.5 Gy). Topical application of the prostaglandin resulted in protection that yielded 52 +/- 3 (8.5 Gy), 34 +/- 4 (10 Gy), and 3.2 +/- 0.9 (12.5 Gy) hairs per field. Both systemic and topical application of 16,16 dm PGE2 protected from some degree of radiation-induced alopecia, which supports the conclusion that prostaglandins may be useful in the protection of hair follicles in patients treated with radiation for brain tumors.