الفهرس 
Estrogen BiologyOnly 14 pages are availabe for public view
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Abstract
The skin is an important estrogen-responsive endocrine tissue. It can respond to estrogens via specific receptors, and also has the capacity to synthesize active steroids from adrenal precursors. The discovery of estrogen receptor β that appears to have different cell-specific roles to the classic estrogen receptor α, and its presence in the skin indicate the potential for enhanced diversity in the mechanisms of estrogen action in the skin.
Changes in skin function and quality with various stages of life accompany changes in estrogen production. Estrogens improve skin in many ways; they increase the skin water-holding capacity, by increasing sphingolipids and glycol-saminoglycans, preventing its dryness. They increase skin thickness by promoting the expression of cyclin D2, suppression of oxidative stress induced apoptosis in keratinocytes, and increasing collagen I and III content in the dermis. Estrogens also improve the mechanical properties of the skin and prevent laxity and facial wrinkling as they increase the number and improve the orientation of elastic fibers, and increase collagen III and hyalouronic acid in the dermis. Estrogens have a major role in the regulation of skin perfusion and temperature homeostasis; they enhance the postischemic skin blood flow and improve vascular reactivity in the cutaneous microcirculation. Estrogens have been shown to prolong the anagen phase of the hair growth cycle in human frontotemporal scalp and inhibit the hair shaft elongation in human occipital scalp hair follicles in both males and females. They also influence the skin pigmentation and decrease the sebaceous gland secretion, and most importantly enhance cutaneous wound healing, particularly chronic wounds such as venous ulcers and pressure ulcers, by modulating the inflammatory response, cytokine expression and matrix deposition, accelerating re-epithelization, stimulating angiogenesis and wound contraction, and regulating proteolysis.
Menopause and the accompanying relative estrogen loss are known to have a profound impact on skin. Estrogen replacement treatment in postmenopausal women has been shown to prevent and reduce the symptoms of skin aging. However, the use of systemic HRT has been reported to be associated with increased risk of coronary heart diseases and breast cancer. For this reason HRT can not be recommended to treat skin aging and it is better to use topical estrogen preparations. Phytoestrogens, non-steroidal plant compounds with estrogen-like biological activity, seem to be a promising alternative for skin aging treatment.
Estrogens were also found to have immunoregulatory roles in skin pathological conditions. At physiological levels, estrogen has the ability to boost immunity and to attenuate production of pro-inflammatory cytokines, thus serving as a systemic anti-inflammatory agent. Also it can serve as a therapeutic agent in androgenetic alopecia and hirsutism as it has the ability to modify androgen metabolism in dermal papillae of the hair follicle. It also opposes the effects of androgens on the sebaceous gland reducing the sebum production and leading to an improvement in acne, thus oral contraceptive pills are an important option in treatment of acne in women that are not responsive to traditional treatment. In psoriasis, changes in estrogen levels affect the natural course of the disease, and exogenous estrogen may have anti-psoriatic effects and also a synergistic effect to corticosteroids in the treatment of psoriasis.
On the other hand, estrogen may promote the development of other diseases such as pyogenic granuloma, and it has been suggested to be involved in the depigmentation process and oxidative stress in vitiligo leading to initiation or rapid progression of the disease. Alteration of estrogen metabolism has been observed in patients with autoimmune disorders and anti-estrogen medications cause improvement in dermatomyositis rash. Estrogen receptor positivity has been demonstrated in most skin tumors such as malignant melanoma, sweat gland tumors, basal cell carcinoma, and some vascular tumors. However, SERMs have only been successfully used in treatment of primary mucinous carcinoma and few cases of metastatizing eccrine adenocarcinoma.