الفهرس 
Chemistry of steroid hormonesOnly 14 pages are availabe for public view
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Abstract
The Skin is under the control of many steroid hormones, namely estrogen, progesterone, androgens and glucocorticoids. The parent compound from which all steroids are derived is cholesterol. The major circulating androgens dehydroepia-ndrosterone sulfate and androstenedione, are predominantly produced in the adrenal glands, and testosterone and 5α-dihydrotestosterone are mainly synthesized in the gonads. Testosterone in women and 5 α -dihydrotestosterone in both genders are also synthesized in the skin.
Androgens affect several functions of the human skin, such as sebaceous gland growth and differentiation, hair growth, epidermal barrier homeostasis and wound healing. Their effects are mediated by binding to nuclear androgen receptors .Androgen activation and deactivation are mainly intracellular events. They differ from cell type to cell type and between cells at different locations.
Skin cells express all androgen metabolizing enzymes required for the independent cutaneous synthesis of androgens and the development of hyperandrogenism-associated conditions and diseases, such as acne, hirsutism and androgenetic alopecia. The major thrust of drug design for the treatment of androgen- associated disorders has been directed against several levels of androgen function and metabolism. Partial effectiveness has only been achieved either by androgen depletion, inhibition of androgen metabolism or blockade of the androgen receptor.
Although it has been recognized for some time that estrogens have significant effects on many aspects of skin physiology and pathophysiology, studies on estrogen action in skin have been limited. However, estrogens clearly have an important function in many components of human skin including the epidermis, dermis, vasculature, hair follicle and the sebaceous, eccrine and apocrine glands, having significant roles in skin aging, pigmentation, hair growth. It prevents or reverses skin atrophy, dryness and wrinkles associated with chronological or photo-aging. Estrogen maintains skin moisture by increasing acid mucopolysaccharide or hyaluronic acid levels in the dermis .It is now time to readdress many of the outstanding questions regarding the role of estrogens in skin and improve physiology and interaction of steroid hormones and their receptors in human skin. Not only will this lead to a better understanding of estrogen action, but may also provide a basis for further interventions in pathological processes that involve dysregulation of estrogen action.
The major naturally occurring glucocorticoid is cortisol which is synthesized from cholesterol by adrenal cortex. In normal state less than 5% of circulating cortisol is un-bound and is the active form. The remainder 95% is inactive as it bounds to cortisol – binding globulin.Cortisol is metabolized by the liver and exerts hormonal effects on virtually every tissue in the body.
Skin atrophy is the most frequent and important side effect of topical GC therapy, with major consequences because it is irreversible and the thinned skin is fragile and has a diminished barrier function. For over 30 years, the effects of GCs on skin have been investigated showing reduced proliferation of GC target cells, keratinocytes and fibroblasts, disturbed metabolism of ECM proteins.
In addition progesterone is a female hormone which metabolized in liver and exert their action through progesterone receptors , there are two isoforms (PR-A) and (PR-B) . It has a little effect on skin but it induce a condition which called autoimmune progesterone dermatitis (APD) which is a condition in which the menstrual cycle is associated with a number of skin findings such as urticaria, eczema, angioedema, and others. In affected women, it occurs 3–10 days prior to the onset of menstrual flow, and resolves 2 days into menses. The use of systemic glucocorticoids, usually in high doses, has been reported to control the cutaneous lesions of APD is some studies.