An investigation of apoptosis in androgenetic alopecia.

While the androgens, including dihydrotestosterone (DHT), have been implicated in the development of androgenetic alopecia (AGA), the exact mechanism by which they exert their effects is unknown. As apoptosis is an integral component of the normal cycling of human hair, we investigated individuals clinically affected by AGA to assess whether objective differences in the expression of apoptosis related immunohistochemical markers could be observed in scalp biopsies. Specimens from 13 alopecic male cadavers were stained with bcl-2 and terminal deoxynucleotidetransferase dUTP fluorescein nick end-labeling (TUNEL) methods to assess apoptotic activity in affected and unaffected areas of the scalp. Immunoreactivity was analyzed by quantifying nuclear staining differences within the same individual. Sections from two living human volunteers were obtained to establish the method validity. Significant differences in bcl-2 expression were observed between areas of the scalp clinically affected and unaffected by AGA. The Gaussian distribution of bcl-2 staining suggests that a relatively uniform population of follicles exists at the frontal hairline and/or synchrony of follicular cycling occurs in AGA. The apoptosis "hot spot" described by TUNEL staining in the bulge-isthmus region of the murine follicle is also identifiable in the human follicle.