Leptin of Dermal Adipose Tissue Is Differentially Expressed During the Hair Cycle and Contributes to Adipocyte-Mediated Growth Inhibition of Anagen-Phase Vibrissa Hair

The study explored the role of leptin in hair cycle progression, focusing on its expression in dermal white adipose tissue (DWAT) and its impact on hair growth. Leptin levels varied during the hair cycle, being lowest in early anagen, increasing in late anagen, and peaking in telogen. Leptin receptors were found in hair follicle epithelium in both anagen and telogen phases in mice and humans. The research showed that leptin contributed to adipocyte-mediated growth inhibition of anagen-phase vibrissa hair in vitro. The study suggested leptin as a key factor in hair cycle progression, though the inhibitory effect of pre-adipocytes on hair growth might involve other factors, as they expressed lower leptin levels. The findings contrasted with previous studies that identified leptin as an anagen inducer, possibly due to different experimental designs. The exact role of DWAT-derived leptin on pelage hair growth and cycling remained unclear.