Activity of Type 1 5α-Reductase Is Greater in the Follicular Infrainfundibulum Compared with the Epidermis

February 1997 in “ British Journal of Dermatology ”

Diane Thiboutot, Helen Knaggs, Kathyrn Gilliland, S. Hagari

TLDR The enzyme type 1 5α-reductase is more active in the hair follicle's lower part than in the skin's outer layer.

The study, conducted on 82 normal subjects, found that type 1 5α-reductase enzyme activity is significantly higher in the follicular infrainfundibulum than in the epidermis. This was observed by measuring enzyme activity in isolated infrainfundibular segments, homogenized epidermis, and microdissected segments of the pilosebaceous unit. The enzyme activity was notably greater at pH 7, indicating the presence of type 1 5α-reductase isozyme. Additionally, the lower follicle showed higher activity at pH 5, suggesting the activity of type 2 isozyme. These results imply that androgens may play a role in follicular keratinization and could be important in understanding conditions like acne vulgaris, hirsutism, and male-pattern hair loss, highlighting the pilosebaceous unit as a key site for sex steroid hormone metabolism in the skin.

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research Role of 5α-Reductase in Health and Disease

101 citations , April 1994 in “Baillière's clinical endocrinology and metabolism”

5α-reductase is essential for male sexual development and its inhibitors have potential in treating various conditions related to hormone action.

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research Activity of Type 1 5α-Reductase Is Greater in the Follicular Infrainfundibulum Compared with the Epidermis

12 citations , February 1997 in “British Journal of Dermatology”

The enzyme type 1 5α-reductase is more active in the hair follicle's lower part than in the skin's outer layer.