Effect of cyclosporin on hair-existing area of nude mice.

We investigated the effect of cyclosporin, as well as minoxidil, testosterone, estradiol and corticosteroid on the hair growth on the hairy part of nude mice. Aliquots of solutions of cyclosporin and other agents were applied once per every day topically on the tails and the lower backs of 5 week-old BALB/c nude mice, for as long as 6 weeks. Cyclosporin prolonged the hair-existing phase of the hair cycle, but did not change the term of the hair cycle, i.e., the resting phase was not affected. Minoxidil, testosterone and estradiol did not influence the hair growth cycle. Combination of cyclosporin and other agents demonstrated that there was neither additive nor synergistic effect, but a high dose of corticosteroid inhibit the cyclosporin effect, as well as suppressing completely the reappearance of the growing phase.