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Testosterone Replacement, Low T, HCG, & Beyond
Testosterone Side Effect Management
Losing hair on head while on TRT plus anastrozole: Causes?
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<blockquote data-quote="madman" data-source="post: 196338" data-attributes="member: 13851"><p>[URL unfurl="true"]https://www.excelmale.com/forum/threads/androgens-and-hair-a-biological-paradox.15225/[/URL]</p><p></p><p>[ATTACH=full]13022[/ATTACH]</p><p>[ATTACH=full]13023[/ATTACH]</p><p></p><p>-------------------------------------------------------------------------------------------------</p><p></p><p></p><p></p><p></p><p><strong>Androgens and hair growth (2008)</strong></p><p><strong></strong></p><p><strong></strong></p><p><strong>ABSTRACT:</strong> Hair’s importance in human communication means that abnormalities like excess hair in hirsutism or hair loss in alopecia cause psychological distress. Androgens are the main regulator of human hair follicles, changing small vellus follicles producing tiny, virtually invisible hairs into larger intermediate and terminal follicles making bigger, pigmented hairs. The response to androgens varies with the body site as it is specific to the hair follicle itself. Normally around puberty, androgens stimulate axillary and pubic hair in both sexes, plus the beard, etc. in men, while later they may also inhibit scalp hair growth causing androgenetic alopecia. Androgens act within the follicle to alter the mesenchyme–epithelial cell interactions, changing the length of time the hair is growing, the dermal papilla size and dermal papilla cell, keratinocyte, and melanocyte activity. A greater understanding of the mechanisms of androgen action in follicles should improve therapies for poorly controlled hair disorders like hirsutism and alopecia.</p><p></p><p></p><p></p><p></p><p><strong>Androgens have paradoxically different effects on human hair follicles</strong></p><p><strong></strong></p><p><strong><em>The importance of androgens is shown when pubertal pubic and axillary hair develops (8–10) in girls before boys (73,74), paralleling increasing circulating androgens. Testosterone also stimulates beard growth in eunuchs and elderly men (75), while castration inhibits beard (19) and balding (76). </em></strong>The roles of androgens and androgen receptors in adult hair is emphasized in XY individuals with complete androgen insufficiency, i.e., unable to respond to androgens due to dysfunctional androgen receptors (77); they develop a female-type phenotype, but lack pubic and axillary hair or androgenetic alopecia (FIG. 1). Sexual hair development is inhibited in growth hormone deficiency (78), suggesting that growth hormone is also essential.</p><p></p><p><strong><em>When androgens stimulate the tiny vellus follicles to produce longer, thicker, more pigmented hairs (FIG. 2), the follicles must pass through the hair cycle, regenerating the lower follicle to carry out such changes (see “The hair follicle growth cycle”). <u>Although androgens stimulate hair growth in many areas, causing greater hair on the face, upper pubic diamond, chest, etc. in men (19), they can also have the opposite effect on specific scalp areas, often in the same individual, causing balding (20)</u>. <u>This involves a reverse transformation via hair follicle cycles, changing large, terminal follicles producing long, often heavily pigmented scalp hairs to miniaturized vellus follicles forming tiny, almost invisible hairs (FIG. 2)</u>. <u>This balding usually occurs in men in a precise pattern starting with regression on the forehead and thinning in the center of the vertex and may continue exposing large areas of the scalp (20,79); the lower sides and back normally retain terminal hair</u>.</em></strong> A different pattern of androgen-dependent alopecia may present in women; the frontal hairline usually remains unaffected while generalized thinning occurs on the central scalp and vertex (80) (FIG. 1). Androgenetic alopecia is reviewed elsewhere (14). <strong><em>At the same time, androgens have no apparent effect in other areas such as the eyelashes (FIG. 2). <u>How does this paradoxical effect occur of one hormone frequently stimulating hair follicles, but also having no effect or inhibiting the same organ in the same person</u>?</em></strong></p><p></p><p>There are also significant differences between androgen-stimulated follicles. Female androgen levels affect axillary and lower pubic follicles, while other follicles require male levels (72,73). Follicle sensitivity also varies; facial follicles enlarge first above the mouth (mustache) and on the chin in boys and hirsute women, spreading gradually over the face and neck (10). Similar gradual progression occurs elsewhere taking many years to show the full response like on a man’s chest (19) or balding (20,79); terminal hairs may only appear on the ear canal in the fifties (49). <strong><em>Interestingly, these slow changes resemble the late androgen-dependent responses in the prostate-causing prostatic benign hypertrophy and carcinoma (81). Beard and axillary hair growth show another paradox; after their pubertal growth spurt, beard growth remains high, while axillary hair growth decreases rapidly in both sexes (19).</em></strong></p><p><strong></strong></p><p><strong></strong></p><p><strong></strong></p><p><strong></strong></p><p><strong>Why do follicles respond so differently?</strong></p><p><strong></strong></p><p><strong><em>These contrasts must be due to intrinsic differences in gene expression within follicles at different sites, since all receive the same circulating hormones and use the same receptors. </em></strong>A follicle’s retention of it's original androgen response when transplanted, the basis of cosmetic hair transplants, confirms this (82).<strong><em> Presumably, this genetic programming occurs during embryonic patterning processes. The molecular mechanisms involved in the development of different follicle types are not clear, but secreted signaling factors (such as Eda, sonic hedgehog, Wnt) and various growth factor families (like the BMPs), nuclear factors (including various homeobox genes), and others such as Hairless and Tabby, plus transmembrane and extracellular matrix molecules are all implicated (83,84).</em></strong></p><p><strong><em></em></strong></p><p><strong><em>Human follicles require androgens to initiate these marked changes.</em></strong> <strong><em>However, if adult men are castrated, although beard growth falls (19) and balding halts (85), neither returns to prepubertal levels, indicating that androgens have altered some gene expression permanently or that the lower androgen levels provided by the adrenals can maintain a partial effect.</em></strong> Increased summer beard growth (3), probably due to raised androgens (Seasonal changes in human hair growth), and inhibition of hirsutism (86) or regrowth stimulation in androgenetic alopecia (87,88) by drugs interfering with androgen action confirms that androgens are also needed to maintain follicular responses.</p><p></p><p><strong><em>Genetics also appears important (reviewed in 1).</em></strong> Heavy beard growth (19) and balding (75) run in families and Caucasians generally exhibit more hair than Japanese (19) and more baldness than Africans (89). Several genes have been investigated for association with androgen-sensitive hair disorders with some links with those involved with androgen metabolism or receptors (reviewed (1)). Interestingly, women with polycystic ovaries and their brothers with early balding show a link to the steroid metabolism gene, CYP17 (90). A recent study of androgenetic alopecia families suggests a new susceptibility gene on chromosome locus 3q26 (91).</p><p></p><p></p><p></p><p>[ATTACH=full]13024[/ATTACH]</p><p>[ATTACH=full]13025[/ATTACH]</p><p><strong>FIG. 1. Human hair patterns under differing endocrine conditions. Visible (i.e. terminal) hair with protective functions normally develops in children on the scalp, eyelashes, and eyebrows. Once puberty occurs, more terminal hair develops on the axilla and pubis in both sexes and on the face, chest, limbs, and often on the back in men. <u>Androgens also stimulate hair loss from the scalp in men with the appropriate genes in a patterned manner causing androgenetic alopecia</u>. People with various androgen insufficiency syndromes (lower panel) demonstrate that none of these occurs without functional androgen receptors and that only axillary and female patterns of lower pubic triangle hairs are formed in the absence of 5α-reductase type 2. Male pattern hair growth (hirsutism) occurs in women with abnormalities of plasma androgens or from idiopathic causes and women may also develop a different form of hair loss, female androgenetic alopecia. Reproduced from Randall 2000 (132).</strong></p><p></p><p></p><p></p><p></p><p>[ATTACH=full]13026[/ATTACH]</p><p>[ATTACH=full]13027[/ATTACH]</p><p>[ATTACH=full]13028[/ATTACH]</p><p><strong>FIG. 2.<u> Androgens have paradoxically different effects on human hair follicles depending on their body site</u>. During, and after, puberty androgens stimulate the gradual transformation of small follicles producing tiny, virtually colorless, vellus hairs to terminal follicles producing longer, thicker, and more pigmented hairs (upper panel) (19). These changes involve passing through the hair cycle (see FIG. 3). At the same time, many follicles on the scalp and eyelashes continue to produce the same type of hair, apparently unaffected by androgens (middle panel). <u>In complete contrast, androgens may inhibit follicles on specific areas of the scalp in genetically susceptible individuals causing the reverse transformation of terminal follicles to vellus ones and androgenetic alopecia</u> (20). Diagram reproduced from Randall 2000 (132).</strong></p><p></p><p></p><p></p><p></p><p></p><p>[ATTACH=full]13029[/ATTACH]</p><p><strong>FIG. 3. The hair follicle growth cycle. Hair follicles go through well-established repeated cycles of development and growth (anagen), regression (catagen), and rest (telogen) (1,2) to enable the replacement of hairs, often by another of differing color or size. An additional phase, exogen, has been reported where the resting club hair is released (42–44).</strong></p></blockquote><p></p>
[QUOTE="madman, post: 196338, member: 13851"] [URL unfurl="true"]https://www.excelmale.com/forum/threads/androgens-and-hair-a-biological-paradox.15225/[/URL] [ATTACH type="full" alt="Screenshot (3587).png"]13022[/ATTACH] [ATTACH type="full" alt="Screenshot (3588).png"]13023[/ATTACH] ------------------------------------------------------------------------------------------------- [B]Androgens and hair growth (2008) ABSTRACT:[/B] Hair’s importance in human communication means that abnormalities like excess hair in hirsutism or hair loss in alopecia cause psychological distress. Androgens are the main regulator of human hair follicles, changing small vellus follicles producing tiny, virtually invisible hairs into larger intermediate and terminal follicles making bigger, pigmented hairs. The response to androgens varies with the body site as it is specific to the hair follicle itself. Normally around puberty, androgens stimulate axillary and pubic hair in both sexes, plus the beard, etc. in men, while later they may also inhibit scalp hair growth causing androgenetic alopecia. Androgens act within the follicle to alter the mesenchyme–epithelial cell interactions, changing the length of time the hair is growing, the dermal papilla size and dermal papilla cell, keratinocyte, and melanocyte activity. A greater understanding of the mechanisms of androgen action in follicles should improve therapies for poorly controlled hair disorders like hirsutism and alopecia. [B]Androgens have paradoxically different effects on human hair follicles [I]The importance of androgens is shown when pubertal pubic and axillary hair develops (8–10) in girls before boys (73,74), paralleling increasing circulating androgens. Testosterone also stimulates beard growth in eunuchs and elderly men (75), while castration inhibits beard (19) and balding (76). [/I][/B]The roles of androgens and androgen receptors in adult hair is emphasized in XY individuals with complete androgen insufficiency, i.e., unable to respond to androgens due to dysfunctional androgen receptors (77); they develop a female-type phenotype, but lack pubic and axillary hair or androgenetic alopecia (FIG. 1). Sexual hair development is inhibited in growth hormone deficiency (78), suggesting that growth hormone is also essential. [B][I]When androgens stimulate the tiny vellus follicles to produce longer, thicker, more pigmented hairs (FIG. 2), the follicles must pass through the hair cycle, regenerating the lower follicle to carry out such changes (see “The hair follicle growth cycle”). [U]Although androgens stimulate hair growth in many areas, causing greater hair on the face, upper pubic diamond, chest, etc. in men (19), they can also have the opposite effect on specific scalp areas, often in the same individual, causing balding (20)[/U]. [U]This involves a reverse transformation via hair follicle cycles, changing large, terminal follicles producing long, often heavily pigmented scalp hairs to miniaturized vellus follicles forming tiny, almost invisible hairs (FIG. 2)[/U]. [U]This balding usually occurs in men in a precise pattern starting with regression on the forehead and thinning in the center of the vertex and may continue exposing large areas of the scalp (20,79); the lower sides and back normally retain terminal hair[/U].[/I][/B] A different pattern of androgen-dependent alopecia may present in women; the frontal hairline usually remains unaffected while generalized thinning occurs on the central scalp and vertex (80) (FIG. 1). Androgenetic alopecia is reviewed elsewhere (14). [B][I]At the same time, androgens have no apparent effect in other areas such as the eyelashes (FIG. 2). [U]How does this paradoxical effect occur of one hormone frequently stimulating hair follicles, but also having no effect or inhibiting the same organ in the same person[/U]?[/I][/B] There are also significant differences between androgen-stimulated follicles. Female androgen levels affect axillary and lower pubic follicles, while other follicles require male levels (72,73). Follicle sensitivity also varies; facial follicles enlarge first above the mouth (mustache) and on the chin in boys and hirsute women, spreading gradually over the face and neck (10). Similar gradual progression occurs elsewhere taking many years to show the full response like on a man’s chest (19) or balding (20,79); terminal hairs may only appear on the ear canal in the fifties (49). [B][I]Interestingly, these slow changes resemble the late androgen-dependent responses in the prostate-causing prostatic benign hypertrophy and carcinoma (81). Beard and axillary hair growth show another paradox; after their pubertal growth spurt, beard growth remains high, while axillary hair growth decreases rapidly in both sexes (19).[/I] Why do follicles respond so differently? [I]These contrasts must be due to intrinsic differences in gene expression within follicles at different sites, since all receive the same circulating hormones and use the same receptors. [/I][/B]A follicle’s retention of it's original androgen response when transplanted, the basis of cosmetic hair transplants, confirms this (82).[B][I] Presumably, this genetic programming occurs during embryonic patterning processes. The molecular mechanisms involved in the development of different follicle types are not clear, but secreted signaling factors (such as Eda, sonic hedgehog, Wnt) and various growth factor families (like the BMPs), nuclear factors (including various homeobox genes), and others such as Hairless and Tabby, plus transmembrane and extracellular matrix molecules are all implicated (83,84). Human follicles require androgens to initiate these marked changes.[/I][/B] [B][I]However, if adult men are castrated, although beard growth falls (19) and balding halts (85), neither returns to prepubertal levels, indicating that androgens have altered some gene expression permanently or that the lower androgen levels provided by the adrenals can maintain a partial effect.[/I][/B] Increased summer beard growth (3), probably due to raised androgens (Seasonal changes in human hair growth), and inhibition of hirsutism (86) or regrowth stimulation in androgenetic alopecia (87,88) by drugs interfering with androgen action confirms that androgens are also needed to maintain follicular responses. [B][I]Genetics also appears important (reviewed in 1).[/I][/B] Heavy beard growth (19) and balding (75) run in families and Caucasians generally exhibit more hair than Japanese (19) and more baldness than Africans (89). Several genes have been investigated for association with androgen-sensitive hair disorders with some links with those involved with androgen metabolism or receptors (reviewed (1)). Interestingly, women with polycystic ovaries and their brothers with early balding show a link to the steroid metabolism gene, CYP17 (90). A recent study of androgenetic alopecia families suggests a new susceptibility gene on chromosome locus 3q26 (91). [ATTACH type="full" alt="Screenshot (3589).png"]13024[/ATTACH] [ATTACH type="full" alt="Screenshot (3590).png"]13025[/ATTACH] [B]FIG. 1. Human hair patterns under differing endocrine conditions. Visible (i.e. terminal) hair with protective functions normally develops in children on the scalp, eyelashes, and eyebrows. Once puberty occurs, more terminal hair develops on the axilla and pubis in both sexes and on the face, chest, limbs, and often on the back in men. [U]Androgens also stimulate hair loss from the scalp in men with the appropriate genes in a patterned manner causing androgenetic alopecia[/U]. People with various androgen insufficiency syndromes (lower panel) demonstrate that none of these occurs without functional androgen receptors and that only axillary and female patterns of lower pubic triangle hairs are formed in the absence of 5α-reductase type 2. Male pattern hair growth (hirsutism) occurs in women with abnormalities of plasma androgens or from idiopathic causes and women may also develop a different form of hair loss, female androgenetic alopecia. Reproduced from Randall 2000 (132).[/B] [ATTACH type="full" alt="Screenshot (3591).png"]13026[/ATTACH] [ATTACH type="full" alt="Screenshot (3592).png"]13027[/ATTACH] [ATTACH type="full" alt="Screenshot (3593).png"]13028[/ATTACH] [B]FIG. 2.[U] Androgens have paradoxically different effects on human hair follicles depending on their body site[/U]. During, and after, puberty androgens stimulate the gradual transformation of small follicles producing tiny, virtually colorless, vellus hairs to terminal follicles producing longer, thicker, and more pigmented hairs (upper panel) (19). These changes involve passing through the hair cycle (see FIG. 3). At the same time, many follicles on the scalp and eyelashes continue to produce the same type of hair, apparently unaffected by androgens (middle panel). [U]In complete contrast, androgens may inhibit follicles on specific areas of the scalp in genetically susceptible individuals causing the reverse transformation of terminal follicles to vellus ones and androgenetic alopecia[/U] (20). Diagram reproduced from Randall 2000 (132).[/B] [ATTACH type="full" alt="Screenshot (3594).png"]13029[/ATTACH] [B]FIG. 3. The hair follicle growth cycle. Hair follicles go through well-established repeated cycles of development and growth (anagen), regression (catagen), and rest (telogen) (1,2) to enable the replacement of hairs, often by another of differing color or size. An additional phase, exogen, has been reported where the resting club hair is released (42–44).[/B] [/QUOTE]
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Testosterone Replacement, Low T, HCG, & Beyond
Testosterone Side Effect Management
Losing hair on head while on TRT plus anastrozole: Causes?
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