Estrogen target cells in the skin

Estrogen deficiency - a central paradigm in age-related impaired healing?

Wound healing is a dynamic biological process achieved through four sequential, overlapping phases; hemostasis, inflammation, tissue proliferation and remodeling. For effective wound healing, all four phases must occur in the appropriate order and time frame. It is well accepted that the wound healing process becomes disrupted in the elderly, increasing the propensity of non-healing wound states that can lead to substantial patient morbidity and an enormous financial burden on healthcare systems. Estrogen deprivation in the elderly has been identified as the key driver of age-related delayed wound healing in both genders, with topical and systemic estrogen replacement reversing the detrimental effects of aging on wound repair. Evidence suggests estrogen deprivation may contribute to the development of chronic wound healing states in the elderly but research in this area is somewhat limited, warranting further investigations. Moreover, although the beneficial effects of estrogen on cutaneous healing have been widely explored, the development of estrogen-based treatments to enhance wound repair in the elderly have yet to be widely exploited. This review explores the critical role of estrogen in reversing age-related impaired healing and evaluates the prospect of developing more focused novel therapeutic strategies that enhance wound repair in the elderly via activation of specific estrogen signaling pathways in regenerating tissues, whilst leaving non-target tissues largely unaffected.

Effect of bilateral oophorectomy on wound healing of the rabbit vagina

We aimed to assess the effect of bilateral oophorectomy on vaginal wound healing in three groups of New Zealand White rabbits (24 rabbits each). Group 1 underwent bilateral oophorectomy, group 2 underwent a sham surgery, and group 3 served as control. Standardized vaginal tissue specimens were harvested and assessed for wound and scar surface area and tensiometric analysis before wounding, and sequentially thereafter, showing that vaginal wound closure, scar contraction, and recovery of biomechanical properties are significantly slower in oophorectomized rabbits.

Sweat gland epithelial and myoepithelial cells are vitamin D targets

Nuclear receptor binding of 1,25(OH)(2)-vitamin D(3) (vitamin D) in skin keratinocytes of epidermis, hair sheaths and sebaceous glands was discovered through receptor microscopic autoradiography. Extended experiments with (3)H-1,25(OH)(2)-vitamin D(3) and its analog (3)H-oxacalcitriol (OCT) now demonstrate nuclear receptor binding in sweat gland epithelium of secretory coils and ducts as well as in myoepithelial cells, as studied in paws of nude mice after i.v. injection. The results suggest genomic regulation of cell proliferation and differentiation, as well as of secretory and excretory functions, indicating potential therapies for impaired secretion as in hypohidrosis of aged and diseased skin.

Effect of estrogens on skin aging and the potential role of SERMs

In humans, structural and functional changes attributable to aging are more visibly evident in the skin than in any other organ. Estrogens have significant effects on skin physiology and modulate epidermal keratinocytes, dermal fibroblasts and melanocytes, in addition to skin appendages including the hair follicle and the sebaceous gland. Importantly, skin aging can be significantly delayed by the administration of estrogen. This paper reviews the effects of estrogens on skin and the mechanisms by which estrogens can alleviate the changes due to aging that occur in human skin. The relevance of estrogen replacement therapy (HRT) in postmenopausal women and the potential value of selective estrogen receptor modulators (SERMs) as a therapy for diminishing skin aging are also highlighted.

The hair follicle as an estrogen target and source

For many decades, androgens have dominated endocrine research in hair growth control. Androgen metabolism and the androgen receptor currently are the key targets for systemic, pharmacological hair growth control in clinical medicine. However, it has long been known that estrogens also profoundly alter hair follicle growth and cycling by binding to locally expressed high-affinity estrogen receptors (ERs). Besides altering the transcription of genes with estrogen-responsive elements, 17beta-estradiol (E2) also modifies androgen metabolism within distinct subunits of the pilosebaceous unit (i.e., hair follicle and sebaceous gland). The latter displays prominent aromatase activity, the key enzyme for androgen conversion to E2, and is both an estrogen source and target. Here, we chart the recent renaissance of estrogen research in hair research; explain why the hair follicle offers an ideal, clinically relevant test system for studying the role of sex steroids, their receptors, and interactions in neuroectodermal-mesodermal interaction systems in general; and illustrate how it can be exploited to identify novel functions and signaling cross talks of ER-mediated signaling. Emphasizing the long-underestimated complexity and species-, gender-, and site-dependence of E2-induced biological effects on the hair follicle, we explore targets for pharmacological intervention in clinically relevant hair cycle manipulation, ranging from androgenetic alopecia and hirsutism via telogen effluvium to chemotherapy-induced alopecia. While defining major open questions, unsolved clinical challenges, and particularly promising research avenues in this area, we argue that the time has come to pay estrogen-mediated signaling the full attention it deserves in future endocrinological therapy of common hair growth disorders.

The modulation of aromatase and estrogen receptor alpha in cultured human dermal papilla cells by dexamethasone: a novel mechanism for selective action of estrogen via estrogen receptor beta?

Steroid hormones have important modulatory effects on the hair follicle, but the mechanisms by which they regulate human hair growth are still poorly understood. It is now clear that there are two distinct estrogen receptors (estrogen receptor alpha (ERalpha) and estrogen receptor beta (ERbeta)) that bind 17beta-estradiol. Since the follicular dermal papilla is known to control hair growth, and steroid hormones regulate receptor and aromatase expression in other tissues, we tested the hypothesis that steroid hormones would similarly modulate estrogen receptor and/or aromatase expression in cultured dermal papilla cells derived from human hair follicles. Primary cultures of non-balding occipital and frontal scalp and beard dermal papilla cells (n = 10) were established. Immunocytochemical studies showed the expression of ERalpha in both the cytoplasm and nucleus, whereas ERbeta was confined to the nuclei. The cells derived from occipital scalp were also incubated for 24 hours with 10 nM of either 17beta-estradiol, estrone, testosterone, 5alpha-dihydrotestosterone, 5alpha-androstane-3alpha, 17beta-diol, 5alpha-androstane-3beta, 17beta-diol, or 100 nM tamoxifen or dexamethasone in phenol red-free, serum-free medium to measure the steady-state levels of ERalpha, ERbeta, and aromatase mRNA by semiquantitative reverse transcriptase-PCR. Although androgens and estrogens did not alter ERalpha mRNA levels, treatment with dexamethasone significantly reduced ERalpha levels to 38% of the untreated control. By contrast, ERbeta mRNA levels were unaffected by any steroid treatment. Furthermore, dexamethasone significantly stimulated the expression of aromatase mRNA approximately 9-fold. Aromatase activity, assayed by the tritiated water method, was stimulated in both frontal scalp and beard dermal papilla cell cultures by dexamethasone. These observations provide evidence for a glucocorticoid-dependent mechanism whereby the selective action of estradiol via ERbeta may be promoted. Additionally, upregulation of aromatase combined with downregulation of ERalpha provides a basis for selective action of estradiol produced locally by autocrine or paracrine mechanisms.

Oestrogen functions in skin and skin appendages

Oestrogens have significant effects on different cell types important in skin physiology, including the epidermal keratinocytes, dermal fibroblasts and melanocytes. In addition, they can also modulate skin appendages such as the hair follicle, the sebaceous gland and the apocrine glands. Oestrogens may also have important modulatory roles in events such as skin ageing, pigmentation, hair growth, sebum production and skin cancer. It is now recognised that oestrogens can modulate their actions via two distinct intracellular receptors (ERalpha and ERbeta) or via cell surface receptors, which activate specific second messenger signalling pathways. This paper highlights the effects of oestrogens on different components of the skin and reviews some of the more recent developments in terms of receptor expression and cell signalling pathways.

Estrogens and the hair follicle. Ostrogene und der Haarfollikel

While it is undisputed that estrogens (1 beta-estradiol, E2) are mainly involved in skin physiology and operate as potent hair growth modulators, our knowledge about the estrogen target cells in skin and exact signaling pathways is still very limited. The current review provides an overview of estrogen effects on hair follicle cycling, cutaneous expression of estrogen receptors, and potential functions of estrogens in hair biology. We discuss potential target genes of estrogen receptor-mediated signaling in the skin, explore the interplay of estrogens with other hormones, growth factors and enzymes, and define major open questions in this intriguing and far too long neglected area of hair research.

Potential role of estrogens in wound healing

Estrogens play a vital role in the development of sexually dimorphic characteristics essential for reproduction. In recent years, insight has been gained into the role of estrogens in non-reproductive pathophysiological processes, including neoplasia, vascular disease and osteoporosis. Intriguingly, the skin appears to act as an end-organ target for estrogenic action; marked structural and functional skin changes occurring after the menopause can be related to altered hormonal profiles. One of the most important consequences of such hormonal changes is the age-related delay in cutaneous wound healing, leading to substantial morbidity and mortality, and increased costs to health services. Reduced estrogen levels have major downstream effects on cellular and tissue responses to injury; such downstream effects include impaired cytokine signal transduction, unchecked inflammation, and altered protein balance, and have a major impact on the rate of wound healing. Further understanding of the complex interaction between aging cells and the hormonal micro-environment is essential to develop focused therapeutic strategies to improve cutaneous wound healing in hypogonadal individuals, including the elderly.

Voice impairment and menopause

OBJECTIVE

Menopause rating scales still do not regard voice impairment as a genuine climacteric symptom, although voice changes are frequently reported. The purpose of this study was both to register and differentiate voice alterations and disorders in menopausal women.

DESIGN

A total of 107 women between 37 and 71 years of age who were rated as postmenopausal according to their hormonal status answered a questionnaire on voice changes and vocal discomfort.

RESULTS

Of this group, 49 women mentioned voices changes, and 35 of those women associated these changes with subjective discomfort, whereas 58 women mentioned neither voice changes nor discomfort. Sixteen of the women who mentioned voice changes and eight who did not participated in a comprehensive investigation, which included completion of the Klimax questionnaire, a head and neck examination, videostroboscopy, perceptual evaluation of voice sound, voice range profile measurements, and voice dysfunction index determination.

CONCLUSIONS

Voice changes during menopause might be a common problem seen in clinical practice. Therefore, an additional systematic registration of voice impairment in future menopause rating scales should be considered if further studies confirm our findings of a high prevalence of voice complaints associated with menopause. Severe menopausal voice impairments, even without other climacteric symptoms, should be regarded as an indication for phoniatric examination.

Analysis of type I collagen in the parametrium of women with and without uterine prolapse, according to hormonal status

The content and quality of type I collagen in the parametrium of women with and without uterine prolapse was evaluated. Forty-four consecutive patients were selected and divided into two groups: A, 21 women without uterine prolapse, and B, 23 with uterine prolapse. Patients in group A had uterine leiomyoma and were submitted to abdominal hysterectomy; in those from group B, vaginal hysterectomy was performed for correction of the uterine prolapse. During surgery, fragments of the parametrium were removed and processed for immunohistochemical analysis using polyclonal antibodies for type I collagen. A system of computerized digital imaging analysis was used for the quantification of collagen fibers. There was no difference between collagen content in patients either with or without prolapse, nor between pre- and postmenopausal women with prolapse. A modification of the quality of the collagen fiber was observed, it being longer and more compact in the group without uterine prolapse. In contrast, in the group with prolapse, the fibers were shorter and thinner and areas with large spaces between fibers were found at several points of the parametrium. The conclusion was that patients with uterine prolapse have the same type I collagen content as those without, but the quality of the fiber is modified. The hormonal status also did not affect collagen content.

The biological actions of estrogens on skin

There is still extensive disparity in our understanding of how estrogens exert their actions, particularly in non-reproductive tissues such as the skin. 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, sebum production and skin cancer. The recent discovery of a second intracellular estrogen receptor (ERbeta) with different cell-specific roles to the classic estrogen receptor (ERalpha), and the identification of cell surface estrogen receptors, has provided further challenges to understanding the mechanism of estrogen action. It is now time to readdress many of the outstanding questions regarding the role of estrogens in skin and improve our understanding of the 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.

Estrogen receptor alpha, but not estrogen receptor beta, is involved in the regulation of the hair follicle cycling as well as the thickness of epidermis in male mice

Estrogen is of importance for the regulation of hair growth and epidermal thickness. The effects of estrogen have predominantly been studied in females; however, recent studies demonstrate that estrogen also is critical for males. The aim of this study was to investigate the relative functional importance of estrogen receptor alpha and estrogen receptor beta in the regulation of the hair follicle cycling and epidermal thickness in male mice. Seven month old transgenic male mice, lacking estrogen receptor alpha (ERKO), estrogen receptor beta (BERKO), or both receptors (DERKO), were orchidectomized and treated for 3 week with 17beta-estradiol or vehicle. Orchidectomy induced a synchronized anagen phase of the hair follicles, which was inhibited by 17beta-estradiol treatment in wild-type and BERKO mice, but not in ERKO and DERKO mice. Furthermore, 17beta-estradiol treatment increased the thickness of epidermis in wild-type and BERKO mice, but not in ERKO and DERKO. This study demonstrates that estrogen is of importance for the regulation of hair follicle cycling and epidermal thickness in male mice. The effect on hair follicle cycling is caused by an estrogen receptor alpha mediated inhibition of telogen-anagen transition and the effect of estrogen to increase epidermal thickness is associated with an estrogen receptor alpha mediated increase in the proliferative rate of the keratinocytes in the basal cell layer of the epidermis.

Effects of leuprolide acetate on adhesion formation and wound healing in the rat model

STUDY OBJECTIVE

To assess the effects of a hypoestrogenic state on adhesion formation and reformation and on wound healing in the rat model.

DESIGN

Prospective, randomized study (Canadian Task Force classification I).

SUBJECTS

Forty-eight female Sprague-Dawley rats.

INTERVENTIONS

Rats were injected with gonadotropin-hormone releasing hormone (GnRH) agonist and control rats with normal saline. Two weeks later (day zero) laparotomy was performed to create adhesions and a full-thickness wound on the flank. On day 14 the adhesions were scored and liberated. The rats were sacrificed on day 28 and adhesion reformation was evaluated. The wound surface area was measured serially until complete closure.

MEASUREMENTS AND MAIN RESULTS

Mean adhesion scores on day 14 after adhesion formation were not significantly different between GnRH agonist and control groups. Preadhesiolysis and postadhesiolysis scores were not significantly different. There was no significant difference in size of wounds between groups on days zero, 7, or 14.

CONCLUSION

Administration of a GnRH agonist does not seem to influence postoperative adhesion formation or wound healing in the rat model. (J Am Assoc Gynecol Laparosc 8(1):124-128, 2001)

17beta-estradiol and ICI-182780 regulate the hair follicle cycle in mice through an estrogen receptor-alpha pathway

Estradiol (E(2)) applied topically twice weekly to mouse skin at doses as low as 1 nmol inhibited hair growth by blocking the transition of the hair follicle from the resting phase (telogen) to the growth phase (anagen). In contrast, application of </=10 nmol of other steroids produced limited inhibition. Topical treatment with the estrogen receptor (ER) antagonist ICI-182780 reversed the effects of E(2), and when applied alone, ICI-182780 caused a telogen-to-anagen transition. Both E(2) and ICI-182780 were highly effective at their site of application but not at distant sites, indicating the direct rather than secondary systemic nature of their effects. Western analysis detected a 65-kDa ER-alpha immunoreactive dermal protein, and Northern analysis revealed the presence of a 6.7-kb ER-alpha mRNA. A ribonuclease protection assay confirmed the presence of ER-alpha transcripts but failed to detect ER-beta transcripts. These findings implicate a skin-specific ER-alpha pathway in the regulation of the hair follicle cycle.

The effects of ovarian hormone deficiency on wound contraction in a rat model

OBJECTIVE

To demonstrate the effect of a deficiency of ovarian hormones on the process of wound contraction, using the oophorectomised rat model of the human menopause.

DESIGN

A randomised controlled trial.

POPULATION

Ninety-six adult Wistar rats were randomly allocated into either an oophorectomised group or a sham-oophorectomised control group.

METHODS

Having confirmed a significant reduction in plasma oestradiol levels in the oophorectomised rats, full-thickness excised lesions were made in the flank skin of the adult rats at either two weeks or four months after oophorectomy, so that the effects of two different durations of hormone deficiency could be assessed and compared with the sham-oophorectomised controls. Following wounding, the rats were left for 3, 5, 10 or 22 days; wound contraction was assessed from photographs of the wounds taken at these intervals after injury.

RESULTS

In the rats wounded four months after oophorectomy there was a slower rate of wound contraction, resulting in larger wounds at days 3, 5, 10 and 22, compared with control rats. No significant difference was observed in rats wounded two weeks after oophorectomy, indicating that the effects of ovarian hormone deficiency on this process are delayed.

CONCLUSION

Due to the pivotal role of wound contraction in the process of wound healing these findings may be of clinical relevance and could have an important impact on the administration of hormone replacement therapy.

Receptor localization of steroid hormones and drugs: discoveries through the use of thaw-mount and dry-mount autoradiography

The history of receptor autoradiography, its development and applications, testify to the utility of this histochemical technique for localizing radiolabeled hormones and drugs at cellular and subcellular sites of action in intact tissues. Localization of diffusible compounds has been a challenge that was met through the introduction of the "thaw-mount" and "dry-mount" autoradiographic techniques thirty years ago. With this cellular receptor autoradiography, used alone or combined with other histochemical techniques, sites of specific binding and deposition in vivo and in vitro have been characterized. Numerous discoveries, some reviewed in this article, provided information that led to new concepts and opened new areas of research. As an example, in recent years more than fifty target tissues for vitamin D have been specified, challenging the conventional view about the main biological role of vitamin D. The functions of most of these vitamin D target tissues are unrelated to the regulation of systemic calcium homeostasis, but pertain to the (seasonal) regulation of endo- and exocrine secretion, cell proliferation, reproduction, neural, immune and cardiovascular responses, and adaptation to stress. Receptor autoradiography with cellular resolution has become an indispensable tool in drug research and development, since information can be obtained that is difficult or impossible to gain otherwise.

An estrogen receptor pathway regulates the telogen-anagen hair follicle transition and influences epidermal cell proliferation

The hair follicle is a cyclic, self renewing epidermal structure which is thought to be controlled by signals from the dermal papilla, a specialized cluster of mesenchymal cells within the dermis. Topical treatments with 17-beta-estradiol to the clipped dorsal skin of mice arrested hair follicles in telogen and produced a profound and prolonged inhibition of hair growth while treatment with the biologically inactive stereoisomer, 17-alpha-estradiol, did not inhibit hair growth. Topical treatments with ICI 182,780, a pure estrogen receptor antagonist, caused the hair follicles to exit telogen and enter anagen, thereby initiating hair growth. Immunohistochemical staining for the estrogen receptor in skin revealed intense and specific staining of the nuclei of the cells of the dermal papilla. The expression of the estrogen receptor in the dermal papilla was hair cycle-dependent with the highest levels of expression associated with the telogen follicle. 17-beta-Estradiol-treated epidermis demonstrated a similar number of 5-bromo-2'-deoxyuridine (BrdUrd) S-phase cells as the control epidermis above telogen follicles; however, the number of BrdUrd S-phase basal cells in the control epidermis varied according to the phase of the cycle of the underlying hair follicles and ranged from 2.6% above telogen follicles to 7.0% above early anagen follicles. These findings indicate an estrogen receptor pathway within the dermal papilla regulates the telogen-anagen follicle transition and suggest that diffusible factors associated with the anagen follicle influence cell proliferation in the epidermis.

Distribution of 1,25-dihydroxyvitamin D3[22-oxa] in vivo receptor binding in adult and developing skin

Because of the therapeutic potential of oxacalcitriol (OCT, 22-oxa-dihydroxyvitamin D3), in vivo studies were conducted in adult and neonatal rats to identify the nuclear receptor sites of action in different tissues of the skin. Results were compared with those for 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and oestradiol from previous studies. Autoradiograms were prepared from the dorsal skin of adult rats and the skin of the leg and head regions of neonatal rats 1 or 2 h after the injection of 3H-OCT. Specific nuclear concentrations of radioactivity, eliminated by competition with unlabelled OCT or 1,25(OH)2D3, were found in cells of the epidermis, outer hair sheath, hair bulb and sebaceous glands, but were absent or low in most fibroblasts of the dermis and hypodermis. The strongest nuclear binding of OCT was conspicuous in outer hair sheaths, where it was 1.5 to 3.2 times higher than in keratinocytes of the epidermis. The distribution of nuclear receptors for OCT was similar to that for 1,25(OH)2D3 but in part dissimilar to that for oestradiol. Oestradiol binding was found in the epidermis and hair sheaths, and also predominantly in fibroblasts of the dermis and hair dermal papillae. The results suggest genomic regulatory effects of OCT, similar to the effects of vitamin D, on proliferation, differentiation and activity of keratinocytes, growth and maintenance of hair, and proliferation and secretion of sebaceous glands. This may be utilized therapeutically, since OCT has a lower calcaemic effect than 1,25(OH)2D3.

Vitamin D3 (soltriol) nuclear receptors in abdominal scent gland and skin of Siberian hamster (Phodopus sungorus) localized by autoradiography and immunohistochemistry

In vivo autoradiography with [3H]1,25-dihydroxycholecalciferol (vitamin D, soltriol) and immunostaining with antibodies to vitamin D receptor were applied to identify specific binding sites in the abdominal scent gland of male Siberian hamster (Phodopus sungorus). Nuclear concentration of radiolabeled hormone and receptor antibodies was observed in the corresponding cell types including basal cells of sebaceous glands, cells of the outer hair sheaths and hair bulbs, and also keratinocytes in the epidermis. Cells of the hair dermal papillae and fibroblasts of the dermis did not show nuclear labeling. There was good correspondence between the autoradiographic and immunohistochemical data. The results indicate the presence of receptors for vitamin D-soltriol and suggest a seasonal regulation of scent gland marking activities by this steroid hormone of sunlight in cooperation with the sex steroid testosterone.

Presence of an oestradiol receptor-related protein in the skin: changes during the normal menstrual cycle

OBJECTIVE

To investigate the presence of an oestradiol receptor-related protein (P29) in skin and skin organelles, and to assess changes in its content during the normal menstrual cycle.

DESIGN

An observational study.

SETTING

King's College School of Medicine and Dentistry, London.

SUBJECTS

Twenty-one premenopausal women with regular menstrual cycles undergoing gynaecological surgery. They were allocated to proliferative or secretory phases of the menstrual cycle on the basis of menstrual dating and histological examination of an endometrial sample.

INTERVENTIONS

Small full thickness sections of skin (about 5 mm in depth) taken from the anterior abdominal wall at hysterectomy or laparoscopic sterilization.

MAIN OUTCOME MEASURES

The concentration of the oestradiol receptor-related protein in skin and its organelles was assessed semi-quantitatively, using a monoclonal antibody technique. The intensity of staining was compared between the proliferative and secretory phases of the cycle.

RESULTS

The receptor-related protein was consistently observed in epidermis, sebaceous glands, hair follicles and sweat ducts; there was no significant difference in its concentration between the proliferative and secretory phases of the menstrual cycle. The protein was not present in dermis and sweat ducts.

CONCLUSIONS

Epidermis and some skin organelles contain an oestradiol receptor-related protein and must be considered as oestrogen target tissues. However, the content of this protein does not appear to change significantly during the normal menstrual cycle.

Estradiol distribution and penetration in rat skin after topical application, studied by high resolution autoradiography

Transdermal pathways and targets in the skin for estradiol were investigated using dry-mount autoradiography. 3H-estradiol-17 beta was applied at doses of 30.1 pmol, 120.4 pmol and 301 pmol/cm2 to shaved rat skin in the dorsal neck region. Vehicles were DMSO, ethylene glycol or sesame oil. After 2 h of topical treatment with 30.1 pmol 3H-estradiol x cm-2 dissolved in DMSO a distinct cellular distribution was apparent. Target cells with concentrations of radioactivity were found in epidermis, sebaceous glands, dermal papillae of hair and fibroblasts. After treatment with 120.4 and 301 pmol/cm2, a penetration gradient of radioactivity was recognizable however it masked specific cellular and subcellular uptake. The stratum corneum accumulated and retained radioactivity, apparently forming a depot for the hormone. Strong concentration and retention of the hormone was conspicuous in sebaceous glands for more than 24 h, suggesting that sebaceous glands serve as a second storage site for the hormone. In all autoradiograms two penetration pathways to the dermis were visible: one through the stratum corneum and epidermis, the other through the hair canals and hair sheaths.

Skin changes in menopause

Skin signs and symptoms were examined in 46 menopausal women prior to estrogen replacement therapy. Several symptoms such as pruritus, bruising, dryness and thinning were seen more frequently in sun-exposed skin emphasizing the contribution of photoaging. At the end of a 6-mth treatment period, no significant difference was observed in the prevalence or severity of the cutaneous signs and symptoms when patients receiving transdermal 17 beta-estradiol (Estraderm) were compared with controls (the only exception was cutaneous flushing). Elastic fibers from sun-protected (buttock) skin of menopausal women were studied by light and electron microscopy. In 3 women (ages 30-37) with a history of premature menopause, the elastic fibers had several degenerative changes including coalescence of cystic spaces into lacunae, peripheral fragmentation, granular degeneration and splitting of the fibers into strands. Similar age-related ultrastructural changes are normally found in individuals that are at least 20 yrs older than these patients. These findings are suggestive of a relationship between premature aging of the dermal elastic fibers and estrogen deprivation.

Distribution of an estrogen receptor-related protein (P29) in normal skin and in cultured human keratinocytes

A monoclonal antibody, ERD5, which recognizes a 29Kd phosphoprotein associated with human estrogen receptor of myometrium was used to study the expression of this protein in normal skin and in cultured human keratinocytes. By indirect immunofluorescence, both in vivo and in vitro keratinocytes showed a variable cytoplasmic staining which increased with cell differentiation. SDS gel electrophoresis of soluble extracts of cultured keratinocytes and normal epidermis showed that P29 was a minor protein. Immunoblot analysis demonstrated that ERD5 strongly reacted only with a 29Kd polypeptide band without any cross-reactivity. These data suggest that keratinocytes might be estrogen sensitive like other cells in which P29 has already been located. The exact role of this protein in the keratinocyte differentiation process and its relationship with estrogen receptors remain to be elucidated.

Determination of sex steroid receptor in human basal cell carcinoma

The role of estrogens in the development of skin cancer is controversial. Sex steroids have a profound effect on the epidermis and epidermal appendages. Estradiol in pharmacologic doses has been reported to stimulate basal cell carcinoma in an animal model. Sex hormones act by means of a specific protein receptor. In this study we used a specific, highly sensitive monoclonal antibody to evaluate sex steroid receptors in human basal cell carcinoma. No estrogen or progesterone receptor protein was detected in the basal cell tumor, despite clear positive control tissues. We conclude that these sex steroid receptors are not present in significant amounts to mediate a direct effect in basal carcinoma.

Vitamin D--soltriol the heliogenic steroid hormone: somatotrophic activator and modulator. Discoveries from histochemical studies lead to new concepts

Evidence from autoradiographic studies with 3H 1,25(OH)2 vitamin D3 (soltriol) about its many sites of nuclear binding and multiple actions suggests that the traditional view of "vitamin D and calcium" is too limited and requires modification. A new concept has been developed which proposes that the skin-derived hormone of sunshine, soltriol, is a somatotrophic activator and modulator that affects all vital systems. Regulation of calcium homeostasis is only one of its many actions. Target tissues for soltriol include not only bone, intestine and kidney, but also brain, spinal cord, pituitary, thyroid, endocrine pancreas, adrenal medulla, enteroendocrine cells, thymus, and male and female reproductive organs. Accordingly, actions of soltriol involve effects on autonomic and endocrine regulation with changes in tissue and blood hormone levels, innervation of skeletal muscle, immune and stress response, digestion, blood formation, fertility, pregnancy and lactation, general energy metabolism, mental processes and mood, and others. The skin-mediated transduction of short-wave sunlight induces a purposeful modulation of growth, reproduction and other biological activities in tune with the conditions of the sun cycle and season. Synthesis and actions of vitamin D3-soltriol are dependent not only on the amount of sunlight, but also on the availability of precursor in the skin and access of sunlight, the rate of hydroxylation in liver and kidney, and the modulation of these events by the endocrine status, in particular growth and reproduction. A concept of a five-level control of soltriol synthesis is proposed, in which the hydroxylation steps provide for a sensitive tuning. Relationships between the heliogenic skin-derived hormonal system and the helioprivic pineal-derived hormonal system are recognized and a comprehensive concept of the "endocrinology of sunlight and darkness" is pointed out.

The distribution of p29 protein in normal human skin

In order to identify specific oestrogen-sensitive structures, normal human skin was examined for the binding of the ER D5 antibody which is associated with p29, a 29 kilodalton protein found in the cytoplasm of normal oestrogen-sensitive cells. Strong and specific staining was seen in the epidermis, with a gradient showing the most intense staining in the granular layer. Similar positive staining was seen in the hair follicles and sebaceous glands. Variable staining was seen in the eccrine glands and vessels. These findings demonstrate p29 to be present in these structures, and hence that oestrogens may exert a specific effect on these tissues.

Oestrogen replacement therapy: physiological considerations and new applications

The total impact of the menopause on the health of women and the ultimate benefit/risk ratio of oestrogen replacement therapy are yet to be defined completely. Until these are accomplished, broad general guidelines for the use of oestrogen replacement therapy in all patients cannot be given. Treatment should be individualized to the patient's specific needs. Use of appropriate dosages of oestrogen in combination with progestin administration should reduce risk and enhance benefits for those subjects requiring its use. The development of new non-oral methods of administration should also help.

The ontogeny of the mouse estrogen receptor: the pelvic region

The appearance of estrogen receptors was examined during the course of fetal and neonatal development in the pelvic region of the mouse; 3H-diethylstilbestrol (DES) was administered via the maternal circulation to developing mice on days 4, 7, 10, 13, 14, 15, and 17 of gestation or to neonates on the day of birth. Localization of the ligand was monitored autoradiographically. The earliest appearance of estrogen receptors occurred in the mesenchyme around the genital ducts on day 13 of pregnancy. On subsequent days, estrogen-concentrating cells appeared in certain mammary-gland cells, connective-tissue strands, in perichondrium associated with specific developing bones, skin, interstitial tissue of the testis, in a sheath of cells surrounding the colon, and in the urethra. The significance of cells containing estrogen receptors in these locations is discussed in reference to a transplacental action of estrogens and the clinical ramifications of DES.

Demonstration of estrogen receptors in the skin

The occurence of high affinity and limited capacity estrogen receptors in skin specimens was investigated and the concentrations of cytoplasmic and nuclear receptors were studied in 14 normal and 22 castrated women. The skin estrogen receptor levels were low in all cases examined, although they usually exceeded the limit value used for estrogen receptor levels in breast cancer tissue. The cytoplasmic and nuclear receptor concentrations in normal women varied from 2.4 to 9.0 and from 1.5 to 7.0 fmol/mg cytosol protein, respectively. The receptor was present as a very high affinity binding component (KD = 0.2- 1.6 x 10(-9)M). The estrogen receptor concentrations in the skin during estriol succinate and estriol valerate therapy were at roughly the same level as during the normal menstrual cycle. The patients who received no replacement therapy after castration displayed the lowest skin estrogen receptor levels. The share of nuclear receptors seemed to be smaller on average during the normal menstrual cycle and in castrated patients not given estrogen therapy than in women treated with estriol succinate or estradiol valerate.

Hormone-induced enlargement of receptive fields in trigeminal mechanoreceptive neurons. I. Time course, hormone, sex and modality specificity

The phenomenon of hormone induced enlargement of receptive field area in mechanoreceptive neurons was investigated with respect to time course, hormone, sex and modality specificity. In acute recording experiments, threshold receptive field boundaries of single trigeminal ganglion neurons innervating the facial region of rats were determined for several different treatment groups. Among ovariectomized females injected with estradiol benzoate (EB) for 2, 5 or 10 days, receptive field areas were significantly increased after only 2 days. Enlargement of field areas appeared to be maximal after 5 days of EB. Lordosis behavior was observed after 10 days of EB but not after 2 or 5 days, suggesting that receptive field enlargement occurs independently of hormone induced lordosis behavior. In normal, intact females, receptive field area varied significantly with the estrous cycle (large during estrus, small during diestrus) indicating that this phenomenon is naturally occurring, not dependent upon the method of estrogen administration. Progesterone given for 10 days had no effect on receptive field area. Treatment with 2 days of EB followed by a single progesterone injection produced reliable lordosis but did not result in any further increase in receptive field area beyond the increase produced by 2 days of EB alone. Thus the synergism between estrogen and progesterone that is recognized for induction of lordosis is absent with respect to receptive field enlargement. The small increase in field area following 10 days of testosterone treatment could be accounted for by the fact that such animals, had blood serum estradiol levels comparable to animals given 2 or 5 days of EB, possibly the result of a testosterone to estrogen conversion. It was concluded that hormone induced receptive field enlargement appears specific for estrogen. Castrated male rats treated with 10 days of EB show the same increase in receptive field area as females, indicating that the phenomenon is not specific to females. Analysis of receptive field area as a function of receptive field type and adaptation rate showed that EB induced field area enlargement was specific to rapidly adapting mechanoreceptive neurons.

Hormone-induced enlargement of receptive fields in trigeminal mechanoreceptive neurons. II. Possible mechanisms

Several possible mechanisms to account for hormone-induced enlargement of receptive field areas of individual mechanoreceptive trigeminal neurons of the rat were investigated. Mechanoreceptor sensitivity was estimated by receptive field thresholds and showed no consistent change following systemic estrogen treatment. Alteration of the viscoelastic properties of skin was suggested as 10 days of estrogen treatment caused an acute epidermal hyperplasia (38.7%), but force-displacement measurements revealed no significant change in skin distensibility. Interestingly, both chemical (6-hydroxydopamine) and surgical sympathectomy mimicked the effect of estrogen on receptive field areas by promoting dramatic enlargement of individual neuronal fields without decreasing receptive field force thresholds. Among skin samples from estrogen, 6-hydroxydopamine and surgical sympathectomized animals, only 6-hydroxydopamine treatment caused any significant alteration in skin norepinephrine content. These results strongly suggest an indirect catecholamine involvement in estrogen-induced enlargement of receptive field areas.

A possible role of estrogens in carcinogenesis of non-target tissues

The mitogenic action of the estrogen-receptor complex is supposedly similar in both normal and malignant target tissues. As receptors are present in several types of non-target tissues, in the case of lesions at the nuclear acceptor sites, the complex in those might be able to cause successive mitoses. Estrogen-dependent tumors of non-target tissues have been reported by several investigators. In normal and malignant cells of the breast and some other types of non-endocrine cells, the ability to produce their own estrogens (from circulating precursors) has been shown. The locally formed estrogens might have a role in the initiation of some malignant transformations. Indications of this process are the switching to estrogen production of some neoplastic endocrine or undifferentiated cells, certain ectopic effects displayed by some cancerous tissues, and the possible roles of GH, PRL and cholesterol in the development of some malignancies. The present endocrine system for the synthesis of the sexual hormones might be a specialization of a system at the cellular level. Polypeptide hormones might evolve from regulatory parts of cyclases or phosphodiesterases. Traces of the original biological processes might still be maintained by several cell-types.