Hair cycle control by leptin as a new anagen inducer

The 2013 study concluded that leptin, a hormone associated with energy regulation, also plays a crucial role in hair cycle regulation, specifically as an inducer of the anagen (growth) phase. Injections of leptin into wild-type mice induced hair growth, while leptin receptor-deficient db/db mice showed delayed hair cycles, indicating the importance of leptin receptor signaling. The study also found that leptin is produced by dermal papilla cells under hypoxic conditions and that it activates hair growth signaling pathways in human keratinocytes. The research suggests that leptin or its fragments could be potential treatments for hair loss conditions. The number of mice used in the experiments varied, with three per group for histomorphometry, up to nine for mock treatments, four for human leptin fragment injections, and five for mouse leptin injections.