Change in Hair Cycle and Hair Length in Nude Mice by Administration of Deuterium Oxide

The study investigated the effects of deuterium oxide (D2O) on hair length and the hair cycle in Balb/c nu/nu (nude) mice. It was found that administering 20% or 30% D2O did not alter the hair's gross structure or the proliferative activity of hair matrix cells but did extend the hair cycle duration in a dose-dependent manner. This extension was reversible upon discontinuation of D2O. The increase in hair length was linked to a prolonged hair-existing phase, and an increase in mast cell density in the skin during the anagen VI stage was observed, which may be related to the extended hair cycle. The study suggested that D2O could slow down long-term cycles like the hair cycle, in addition to short-term cycles.