Studies of Common Baldness in the Stumptailed Macaque IV. In Vitro Metabolism of Testosterone in the Hair Follicles

Abstract

The uptake and catabolism of tritiated testosterone by hair follicles from both the bald and hairy regions of the scalp and back of stumptailed macaques were studied in vitro. Testosterone was incorporated into the anagen and telogen stages of both terminal and vellus hair follicles, and its major metabolite appeared to be androstenedione. As a rule, the follicles from the scalp had higher metabolic rates than those of the back. Metabolic activity was higher in the bulb than in the outer root sheath. The total rates of testosterone incorporation and catabolism by the vellus hair follicles from the bald scalp and the terminal hair follicles from the hairy scalp were not markedly different. However, testosterone was catabolized much faster and was retained less by the vellus follicles than by the terminal follicles. The ratio of the metabolites/testosterone was greater than 1 in both the anagen and telogen hair follicles of the frontal bald region. This is the first biochemical finding that gives some characterization to hair follicles from the bald scalp. The physiological significance of the accumulation of biologically rather inactive androstenedione in vellus hair follicles remains unexplained.