Related Experiment Video
Updated: May 18, 2026

A New Technique for Quantitative Analysis of Hair Loss in Mice Using Grayscale Analysis
Published on: March 9, 2015
Androgen actions on the human hair follicle: perspectives
1Department of Regenerative Dermatology, Graduate School of Medicine, Osaka University, Osaka, Japan. inui@r-derma.med.osaka-u.ac.jp
Abstract:
Androgens stimulate beard growth but suppress hair growth in androgenetic alopecia (AGA). This condition is known as 'androgen paradox'. Human pilosebaceous units possess enough enzymes to form the active androgens testosterone and dihydrotestosterone. In hair follicles, 5α-reductase type 1 and 2, androgen receptors (AR) and AR coactivators can regulate androgen sensitivity of dermal papillae (DP). To regulate hair growth, androgens stimulate production of IGF-1 as positive mediators from beard DP cells and of TGF-β1, TGF-β2, dickkopf1 and IL-6 as negative mediators from balding DP cells. In addition, androgens enhance inducible nitric oxide synthase from occipital DP cells and stem cell factor for positive regulation of hair growth in beard and negative regulation of balding DP cells. Moreover, AGA involves crosstalk between androgen and Wnt/β-catenin signalling. Finally, recent data on susceptibility genes have provided us with the impetus to investigate the molecular pathogenesis of AGA.
Related Concept Videos
Accessory Structures of the Skin: Hair Growth and Types
Accessory Structures of the Skin: Hair and Hair Follicles
Hair is a keratinous filament growing out of the epidermis. It is primarily made of dead, keratinized cells. Hair strands originate at the epidermal penetration called the hair follicle. The hair shaft is the part...
Multipotency and Niche of Bulge Stem Cell
Testosterone: Functions and Regulation
Folliculogenesis
Target Cell Response to Hormones
Notably, the cellular response can be regulated by altering the number of receptors expressed in the cell. For example, prolonged exposure to elevated hormone levels results in a gradual decline or down-regulation in the number of receptors for that specific hormone on the cell surface. Conversely, in response to low hormone levels, cells may use up-regulation, producing an...

