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I came across this new study which found that 5 alpha reductase type 1 may play an important role in hair loss too, rather than it just being 5 alpha reductase type 2 that is involved. The superiority of dutasteride over finasteride as a hair loss treatment is likely due to both its more complete inhibition of the type 2 enzyme as well as its additional partial inhibition of the type 1 enzyme.
For your interest, finasteride taken at 1mg a day removes 85-90% of the DHT from the type 2 enzyme, and none of the DHT from the type 1 enzyme. Dutasteride taken at 0.5mg a day removes 98-99% of the DHT from the type 2 enzyme and about half of the DHT from the type 1 enzyme.
Here is the link to the full-text study:
Change in Hair Growth-related Gene Expression Profile in Human Isolated Hair Follicles Induced by 5-alpha Reductase Inhibitors, Dutasteride and Finasteride, in the Presence of Testosterone:
https://www.longdom.org/open-access...licles-induced-by-5alpha-reductase-inhibi.pdf
And I've pasted the abstract below:
Abstract:
Objective:
5-α reductase (5AR) subtypes I and II are suggested to be involved in the development of androgenetic alopecia (Androgenetic Alopecia); however, the involvement of type I 5AR in the pathogenesis of Androgenetic Alopecia and downstream molecular events following androgen receptor inhibition are still poorly understood. We investigated the changes in gene expression levels of growth factors and related molecules responsible for hair growth, such as enzymes and transcription factors, using the bulbar portions of plucked human hair follicles, and evaluated the involvement of type I 5AR in human hair growth.
Methods:
Anagen hairs were plucked from male donors with Androgenetic Alopecia and cultured in medium containing dihydrotestosterone (DHT) or testosterone in the presence or absence of the 5AR inhibitors, dutasteride or finasteride. Total RNA extracted from the bulbar portions of hair follicles was subjected to quantitative reverse transcriptase polymerase chain reaction analysis to assess gene expression levels of growth factors and other related molecules.
Results:
DHT stimulation resulted in a trend to decrease the expression of genes encoding fibroblast growth factor 7 (FGF7; p=0.52), insulin-like growth factor 1 (IGF1; p=0.85) and WNT family member 5A (WNT5a; p=0.08). Subsequently, testosterone stimulation led to decreased expression of genes encoding FGF7 (p=0.53), IGF1 (p=0.93) and WNT5a (p=0.51), which was reversed by dutasteride or finasteride treatment.
Conclusion:
Among the assessed growth factors and other molecules related to hair growth, the expression levels of FGF7, IGF1 and WNT5a were reversed by 5AR inhibitors under testosterone stimulation. Our data suggest this assay may be useful to deeper dissect the effect of 5AR on human hair follicles and supports the previously unreported involvement of type I 5AR in hair growth.
For your interest, finasteride taken at 1mg a day removes 85-90% of the DHT from the type 2 enzyme, and none of the DHT from the type 1 enzyme. Dutasteride taken at 0.5mg a day removes 98-99% of the DHT from the type 2 enzyme and about half of the DHT from the type 1 enzyme.
Here is the link to the full-text study:
Change in Hair Growth-related Gene Expression Profile in Human Isolated Hair Follicles Induced by 5-alpha Reductase Inhibitors, Dutasteride and Finasteride, in the Presence of Testosterone:
https://www.longdom.org/open-access...licles-induced-by-5alpha-reductase-inhibi.pdf
And I've pasted the abstract below:
Abstract:
Objective:
5-α reductase (5AR) subtypes I and II are suggested to be involved in the development of androgenetic alopecia (Androgenetic Alopecia); however, the involvement of type I 5AR in the pathogenesis of Androgenetic Alopecia and downstream molecular events following androgen receptor inhibition are still poorly understood. We investigated the changes in gene expression levels of growth factors and related molecules responsible for hair growth, such as enzymes and transcription factors, using the bulbar portions of plucked human hair follicles, and evaluated the involvement of type I 5AR in human hair growth.
Methods:
Anagen hairs were plucked from male donors with Androgenetic Alopecia and cultured in medium containing dihydrotestosterone (DHT) or testosterone in the presence or absence of the 5AR inhibitors, dutasteride or finasteride. Total RNA extracted from the bulbar portions of hair follicles was subjected to quantitative reverse transcriptase polymerase chain reaction analysis to assess gene expression levels of growth factors and other related molecules.
Results:
DHT stimulation resulted in a trend to decrease the expression of genes encoding fibroblast growth factor 7 (FGF7; p=0.52), insulin-like growth factor 1 (IGF1; p=0.85) and WNT family member 5A (WNT5a; p=0.08). Subsequently, testosterone stimulation led to decreased expression of genes encoding FGF7 (p=0.53), IGF1 (p=0.93) and WNT5a (p=0.51), which was reversed by dutasteride or finasteride treatment.
Conclusion:
Among the assessed growth factors and other molecules related to hair growth, the expression levels of FGF7, IGF1 and WNT5a were reversed by 5AR inhibitors under testosterone stimulation. Our data suggest this assay may be useful to deeper dissect the effect of 5AR on human hair follicles and supports the previously unreported involvement of type I 5AR in hair growth.
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