Identification of androgen, estrogen and progesterone receptor mRNAs in the eye

Oestrogen, ocular function and low-level vision: a review

Over the past 10 years, a literature has emerged concerning the sex steroid hormone oestrogen and its role in human vision. Herein, we review evidence that oestrogen (oestradiol) levels may significantly affect ocular function and low-level vision, particularly in older females. In doing so, we have examined a number of vision-related disorders including dry eye, cataract, increased intraocular pressure, glaucoma, age-related macular degeneration and Leber's hereditary optic neuropathy. In each case, we have found oestrogen, or lack thereof, to have a role. We have also included discussion of how oestrogen-related pharmacological treatments for menopause and breast cancer can impact the pathology of the eye and a number of psychophysical aspects of vision. Finally, we have reviewed oestrogen's pharmacology and suggest potential mechanisms underlying its beneficial effects, with particular emphasis on anti-apoptotic and vascular effects.

Sex-steroid imbalance in females and dry eye

Dry eye (DE) is a multifactorial disorder of the ocular surface unit that results in eye discomfort, visual disturbance and ocular surface damage. It is one of the most common complaints in daily ophthalmic practice. The risk of DE increases with age in both sexes, while its incidence is higher among females. In addition, the condition of menopause in aging women may also contribute to DE onset or worsening as a consequence of an overall hormonal imbalance. Sex hormones play a key role in ocular surface physiology and they impact differently on ocular surface tissues. Reduced estrogen levels were historically thought to be responsible in age-related DE onset but more recent investigations have reconsidered the role of androgens that are present and exert a protective function on the ocular surface. Hormone levels themselves, withdrawal changes in hormone levels, and the changes in hormone-receptor responsiveness are all important factors but it remains to be fully elucidated how estrogen or androgen insufficiency act alone or together in a combined imbalance or interplay to raise the risk of disease. The purpose of this review is to briefly outline current scientific evidence on the influence of androgens and estrogens, on the Lachrymal and Meibomian glands and on ocular surface epithelia including conjunctival goblet cells during reproductive and menopausal periods. The role of sex steroids is also discussed in relation to the pathogenesis of different forms of DE and Sjogren's syndrome (SS). The impact of systemic hormone therapy (HT) in DE post-menopausal women still appears as a controversial issue, despite the many clinical studies. Finally, the outcomes of topical applications of steroid-based products are summarized, underlying the need for potential (tear) biomarker(s) in the rationale of DE-targeted therapy.

Diurnal variation in choroidal thickness in relation to sex, axial length, and baseline choroidal thickness in healthy Korean subjects

PURPOSE

To investigate diurnal variations in choroidal thickness (CT) in relation to various factors in healthy Korean subjects using spectral-domain optical coherence tomography.

METHODS

A prospective study was conducted on 100 healthy volunteers who each underwent measurements of CT in the same subfoveal area using an enhanced depth imaging technique with spectral-domain optical coherence tomography at 8 AM, 11 AM, 2 PM, and 5 PM. Possible correlations between the diurnal variation of CT and other factors, such as sex, axial length (AL), baseline CT (8 AM), blood pressure, and intraocular pressure, were evaluated.

RESULTS

One hundred volunteers with a mean age of 30.1 years were scanned. A significant pattern of diurnal variation was observed, with a mean CT of 278.28 ± 91.78 μm at 8 AM, 271.57 ± 89.08 μm at 11 AM, 266.39 ± 86.18 μm at 2 PM, and 264.92 ± 87.10 μm at 5 PM in a right eye. Right eye and left eye had a similar trend of diurnal cycle. Based on sex, AL, and baseline CT, the pattern of diurnal variation was greater and the amplitude significantly was greater in men, AL ≤ 24 mm and baseline CT ≥ 300 μm (men vs. women: P = 0.048, AL ≤ 24 mm vs. AL > 24 mm: P = 0.036, baseline CT ≥ 300 μm vs. baseline CT < 200 μm: P = 0.002, baseline CT ≥ 300 μm vs. 200 μm ≤ baseline CT < 300 μm: P = 0.008). There were no significant correlations between the diurnal variation of CT and systolic blood pressure, diastolic blood pressure, or intraocular pressure.

CONCLUSION

In men as well as in those with a shorter AL and thick baseline CT, a greater pattern of diurnal variation with significantly greater amplitude was observed.

Cornea in PCOS patients as a possible target of IGF-1 action and insulin resistance

OBJECTIVES

Previous studies suggest that serum IGF-1 is higher in women with polycystic ovary syndrome (PCOS). The ophthalmologic effects of IGF-1 excess have not yet been investigated in women with PCOS. The aim of the current study is to compare the corneal thickness of patients with PCOS and those of healthy subjects.

METHODS

Forty three patients with PCOS and 30 age-matched and gender-matched healthy individuals were enrolled in this cross-sectional study. Central corneal thickness (CCT) was measured in patients with PCOS and in healthy individuals with an ultrasound pachymeter. IGF-1 values were also determined in the study group.

RESULTS

Women with PCOS had significantly higher levels of IGF-1 and homeostasis model assessment (HOMA-IR) levels than the control group. Right and left CCT measurements were higher in the PCOS group than in the control group. A positive correlation between IGF-1 and right and left CCT was identified in both groups. In multiple linear stepwise regression analyses, IGF-1 independently and positively associated with HOMA-IR in women with PCOS. A correlation between total testosterone and CCT was identified in the whole group. In multiple stepwise regression analyses, total testosterone independently and positively associated with left central corneal thickness in the whole group.

CONCLUSIONS

These findings indicate that PCOS has target organ effects on the eye. Consequently, it can change central corneal thickness. Higher IGF-1 levels seem to be the main causes of increased corneal thickness. Insulin resistance in PCOS is one of the underlying causes and promotes increase in IGF-1. We suggest a careful and detailed corneal evaluation in PCOS patients to prevent the potential risk of increased CCT, in addition to the already-known complications.

Gender and cataract--the role of estrogen

There is evidence from epidemiologic data that cataract is more common in women than men. This is not solely due to a higher rate of cataract extraction in women, as is the case in the western world, but several population-based studies show that females have a higher prevalence of lens opacities, especially cortical. There is no firm evidence that lifestyle-related factors are the cause of this gender discrepancy. Focus has therefore been directed towards the role of estrogen in cataract formation. Although data on endogenous and exogenous estrogen involvement in cataractogenesis are conflicting, some studies have indicated that hormone therapy may decrease the risk of cataract and thus be protective. It has been hypothesized that the decrease in estrogen at menopause cause increased risk of cataract in women, i.e. not strictly the concentration of estrogen, but more the withdrawal effect. Estrogens are known to exert several anti-aging effects that may explain the longer lifespan in women, including metabolically beneficial effects, neuroprotection, preservation of telomeres and anti-oxidative properties. Since oxidative stress is considered important in cataractogenesis, studies have investigated the effects of estrogens on lens epithelial cells in culture or in animal models. Several investigators have found protection by physiological concentrations of 17β-estradiol against oxidative stress induced by H2O2 in cultured lens epithelial cells. Although both main types of estrogen receptors, ERα and ERβ, have been demonstrated in lens epithelium, most studies so far indicate that the estrogen-mediated protection in the lens is exerted through non-genomic, i.e. receptor-independent mechanisms, possibly through phosphorylation of extracellular signal-regulated kinase (ERK1/ERK2), a member of the mitogen-activated protein kinase (MAPK)-signaling pathway. Further studies are needed, both epidemiologic as to the role of hormone therapies, and laboratory studies regarding molecular estrogen-mediated mechanisms, in order to comprehend the role of estrogens on cataract formation.

The neurobiology of the meibomian glands

This article compiles research regarding the neuroanatomy of the meibomian glands and their associated blood vessels. After a review of meibomian gland morphology and regulation via hormones, a case for innervation is made based on anatomical findings whereby the nerves lack a myelin sheath and Schwann cells. The localization and co-localization of dopamine beta-hydroxylase, tyrosine hydroxylase, neuropeptide Y, vasoactive intestinal polypeptide, calcitonin gene-related peptide, and substance P are explored with emphasis on differences that exist between species. The presence of the various neuropeptides/neurotransmitters adjacent to the meibomian gland versus the vasculature associated with the meibomian gland is documented so that conclusions can be made with regard to direct and indirect effects. Research regarding the presence of receptors and receptor proteins for these neuropeptides is documented. Evidence supporting the influence of certain neurotransmitters and/or neuropeptides on the meibomian gland is given based on research that correlates changes in meibomian gland morphology and/or tear film with changes in neurotransmitter and/or neuropeptide presence. Conclusions are drawn related to direct and indirect regulation and differences between the various nervous systems.

Sex hormones and the dry eye

The greater prevalence of dry eye in women compared to men suggests that sex hormones may have a role in this condition. This review aims to present evidence for how sex hormones may affect the ocular structures involved in the production, regulation and maintenance of the normal tear film. It is hypothesised that hormone changes alter the homeostasis of the ocular surface and contribute to dry eye. Androgens impact on the structure and function of the meibomian and lacrimal glands and therefore androgen deficiency is, at least in part, associated with the aetiology of dry eye. In contrast, reports of the effects of oestrogen and progesterone on these ocular structures and on the conjunctiva are contradictory and the mechanisms of action of these female-specific sex hormones in the eye are not well understood. The uncertainty of the effects of oestrogen and progesterone on dry eye symptoms is reflected in the controversial relationship between hormone replacement therapy and the signs and symptoms of dry eye. Current understanding of sex hormone influences on the immune system suggests that oestrogen may modulate a cascade of inflammatory events, which underlie dry eye.

Anastrozole for prevention of breast cancer in high-risk postmenopausal women (IBIS-II): an international, double-blind, randomised placebo-controlled trial

BACKGROUND

Aromatase inhibitors effectively prevent breast cancer recurrence and development of new contralateral tumours in postmenopausal women. We assessed the efficacy and safety of the aromatase inhibitor anastrozole for prevention of breast cancer in postmenopausal women who are at high risk of the disease.

METHODS

Between Feb 2, 2003, and Jan 31, 2012, we recruited postmenopausal women aged 40-70 years from 18 countries into an international, double-blind, randomised placebo-controlled trial. To be eligible, women had to be at increased risk of breast cancer (judged on the basis of specific criteria). Eligible women were randomly assigned (1:1) by central computer allocation to receive 1 mg oral anastrozole or matching placebo every day for 5 years. Randomisation was stratified by country and was done with blocks (size six, eight, or ten). All trial personnel, participants, and clinicians were masked to treatment allocation; only the trial statistician was unmasked. The primary endpoint was histologically confirmed breast cancer (invasive cancers or non-invasive ductal carcinoma in situ). Analyses were done by intention to treat. This trial is registered, number ISRCTN31488319.

FINDINGS

1920 women were randomly assigned to receive anastrozole and 1944 to placebo. After a median follow-up of 5·0 years (IQR 3·0-7·1), 40 women in the anastrozole group (2%) and 85 in the placebo group (4%) had developed breast cancer (hazard ratio 0·47, 95% CI 0·32-0·68, p<0·0001). The predicted cumulative incidence of all breast cancers after 7 years was 5·6% in the placebo group and 2·8% in the anastrozole group. 18 deaths were reported in the anastrozole group and 17 in the placebo group, and no specific causes were more common in one group than the other (p=0·836).

INTERPRETATION

Anastrozole effectively reduces incidence of breast cancer in high-risk postmenopausal women. This finding, along with the fact that most of the side-effects associated with oestrogen deprivation were not attributable to treatment, provides support for the use of anastrozole in postmenopausal women at high risk of breast cancer.

FUNDING

Cancer Research UK, the National Health and Medical Research Council Australia, Sanofi-Aventis, and AstraZeneca.

Androgen receptor identification in the diagnosis of eyelid sebaceous carcinomas

PURPOSE

To assess the role of androgen receptor detection in diagnosing eyelid sebaceous carcinomas and to compare it with that of adipophilin.

DESIGN

Retrospective, clinicopathologic study.

METHODS

Ten sebaceous carcinomas (8 invasive, 2 intraepithelial only) were stained immunohistochemically for androgen receptors and were compared with adipophilin staining. Receptor staining also was performed on benign sebaceous tumors (a sebaceoma and an adenoma) and as controls on eyelid basal cell carcinomas, eyelid squamous cell carcinomas, conjunctival squamous dysplasias, and conjunctival melanomas.

RESULTS

All 8 patients with an invasive component of sebaceous carcinoma underwent a biopsy in which the tumor cells showed diffusely positive results for androgen receptors (>20% of cells and usually >40%) and positive results for adipophilin. Eight cases displaying an intraepithelial (or pagetoid) component of spread also showed diffusely positive results for androgen receptors and adipophilin in at least 1 of multiple biopsy samples from each patient. However, in 8 of 21 separate conjunctival biopsy specimens with intraepithelial cytologic atypia, adipophilin results were negative. A sebaceoma and a sebaceous adenoma also showed positive results for both of these biomarkers. Among the controls, squamous carcinomas and melanomas showed negative results for androgen receptors and adipophilin. Basal cell carcinomas displayed focal receptor positivity in fewer than 5% of cells and showed negative results for adipophilin.

CONCLUSIONS

Androgen receptors and adipophilin can separate sebaceous tumors immunohistochemically from squamous carcinomas and melanomas, which showed negative results for both, and from basal cell carcinomas, which showed positive receptor results in a distant minority of cells. Regarding intraepithelial (or pagetoid) spread, androgen receptor detection was more sensitive and reliable than adipophilin in highlighting this component of the disease.

Sex differences in circadian timing systems: implications for disease

Virtually every eukaryotic cell has an endogenous circadian clock and a biological sex. These cell-based clocks have been conceptualized as oscillators whose phase can be reset by internal signals such as hormones, and external cues such as light. The present review highlights the inter-relationship between circadian clocks and sex differences. In mammals, the suprachiasmatic nucleus (SCN) serves as a master clock synchronizing the phase of clocks throughout the body. Gonadal steroid receptors are expressed in almost every site that receives direct SCN input. Here we review sex differences in the circadian timing system in the hypothalamic-pituitary-gonadal axis (HPG), the hypothalamic-adrenal-pituitary (HPA) axis, and sleep-arousal systems. We also point to ways in which disruption of circadian rhythms within these systems differs in the sexes and is associated with dysfunction and disease. Understanding sex differentiated circadian timing systems can lead to improved treatment strategies for these conditions.

Changes in tear film, corneal topography, and refractive status in premenopausal women during menstrual cycle

PURPOSE

To investigate the changes in a questionnaire based subjective symptomatology, tear film break-up time, tear volume, corneal topography, and refractive status in premenopausal women during menstrual cycle.

METHODS

Seventeen premenopausal females and 15 healthy males were enrolled in this prospective study. After routine ophthalmologic examination, an ocular surface disease index questionnaire was administered, tear film break-up time (TBUT), and Schirmer I tests were performed. Keratometry readings and refractive status were also obtained. All examinations were repeated at day 21, day 12 and day 2.

RESULTS

OSDI score in day 21 was significantly lower than that in day 12 (p=0.004) and day 2 (p=0.01) in the female patients; however, no significant change was found in the male subjects (p>0.05). No statistically significant difference was found in TBUT and Schirmer I tests, keratometry, and refraction results in both of the female and male subjects at all of the test points (p>0.05). There was a significant correlation between OSDI score and TBUT (p=0.02, p=0.03, respectively), and Schirmer I test at day 12 (p=0.004, p=0.008, respectively). A significant negative correlation was found between oestrogen level and horizontal keratometry values at day 21 (r=-0.5, p=0.03; r=-0.4, p=0.04, respectively) for the right and left eyes in the female subjects.

CONCLUSION

Our study confirms that fluctuations in the blood levels of oestrogen produce alterations in ocular surface equilibrium during the menstrual cycle and consequently affect the subjective dry eye symptoms in female patients. However, no ocular surface parameter changes were observed.

Progesterone and estrogen receptors in conjunctival melanoma and nevi

BACKGROUND

Since it has been observed that melanocytic lesions can alter their appearance during pregnancy, we analyzed whether hormone receptors are expressed in conjunctival nevi as well as conjunctival melanoma. We further analyzed whether the number of estrogen (ER) or progesterone receptors (PR) might be associated with the disease course in conjunctival melanoma.

METHODS

Twenty-seven paraffin-embedded samples of conjunctival nevi and 27 conjunctival melanoma specimens were examined using immunohistological analysis with antibodies against PR and ER. The percentage of stained cells were analyzed, taking into account patient gender and age. Out of the melanoma group, all patients with complete data for tumor thickness, tumor localization, age at diagnosis, gender, and follow-up including recurrence, metastasis and tumor-related death were included in the second part of the study (n = 15), where hormone receptor rates were associated with tumor outcome, regarding recurrences, metastasis or death. Written consent was received from all included patients.

RESULTS

Both nevi and melanomas showed high rates of PR- and ER-positive cells. In Nevi, 64 ± 25 % of cells stained positive for PR and 35 ± 34 % for ER. In melanoma specimens, 68 ± 30 % showed PR and 44 ± 34 % ER expression. Differences between men and women in expression rates were not statistically significant. Out of 15 melanoma patients (nine female, six male), 53 % (five women and three men) experienced 1-4 recurrences, and four patients developed metastases. The median estimated survival time was 12.2 years. A multivariate survival model taking into account known risk factors for prognosis in conjunctival melanoma confirmed tumor location to be an important predictive factor for outcome (p = 0.05). The rate of PR or ER did not show a statistically significant correlation with the disease course in our cohort.

CONCLUSIONS

We observed that conjunctival melanocytic lesions express hormone receptors, which could explain why these tumors can alter their appearance under hormonal changes. Regarding the prognosis of conjunctival melanoma, no statistically significant correlation between hormone receptor expression and event-free survival was found in this analysis.

Corneal biomechanical parameters during pregnancy

PURPOSE

To evaluate the variation in biomechanical properties and central corneal thickness (CCT) for each trimester during pregnancy and to compare the values with those in nonpregnant women.

METHODS

We prospectively studied the eyes of 32 pregnant and 34 age-matched non-pregnant women. The parameters included corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOP), and corneal-compensated IOP measured by the Ocular Response Analyzer (ORA). The CCT was also measured with an ultrasonic pachymeter attached to the ORA.

RESULTS

The mean age was 27.0 ± 3.8 years in the study group and 28.0 ± 4.1 years in the control group. The mean CH measurement was 10.6 ± 1.4 mmHg in the study group and 10.1 ± 1.3 mmHg in the control group. The mean CRF value was 9.6 ± 1.7 mmHg in the study group and 10.0 ± 1.4 mmHg in the control group. The mean CCT value was 541.1 ± 22.4 µm in the study group and 536.5 ± 27.1 µm in the control group. No statistically significant differences were found regarding CH, CRF, or CCT values between the 2 groups (independent t test, p = 0.160, p = 0.355, p = 0.450, respectively).

CONCLUSIONS

Hormonal changes during pregnancy may not affect corneal biomechanics. This may be due to the balanced effect of the various hormones on the cornea during pregnancy.

17β-estradiol eye drops protect the retinal ganglion cell layer and preserve visual function in an in vivo model of glaucoma

Neuroprotection in glaucoma as a curative strategy complementary to current therapies to lower intraocular pressure (IOP) is highly desirable. This study was designed to investigate neuroprotection by 17β-estradiol (E2) to prevent retinal ganglion cell (RGC) death in a glaucoma model of surgically elevated IOP in rats. We found that daily treatment with E2-containing eye drops resulted in significant E2 concentration in the retina with concomitant profound neuroprotective therapeutic benefits, even in the presence of continually elevated IOP. The number of apoptotic cells in the RGC layer was significantly decreased in the E2-treated group, when compared to the vehicle-treated controls. Deterioration in visual acuity in these animals was also markedly prevented. Using mass spectrometry-based proteomics, beneficial changes in the expression of several proteins implicated in the maintenance of retinal health were also found in the retina of E2-treated animals. On the other hand, systemic side effects could not be avoided with the eye drops, as confirmed by the measured high circulating estrogen levels and through the assessment of the uterus representing a typical hormone-sensitive peripheral organ. Collectively, the demonstrated significant neuroprotective effect of topical E2 in the selected animal model of glaucoma provides a clear rationale for further studies aiming at targeting E2 into the eye while avoiding systemic E2 exposure to diminish undesirable off-target side effects.

High affinity nuclear and nongenomic estradiol binding sites in the human and mouse lens

Estrogen is reported to be protective against cataracts in women and animal models. Immunodetection methods have identified the classic estrogen receptors (ER), ERα and ERβ, in human lens epithelial cells and their RNAs have been detected in the rat and human lens. To verify that estrogen binding occurs in the lens, sensitive [(125)I]-17β-estradiol binding analyses were performed on subcellular lens fractions from women (ages 39-78 years). The presence of high affinity estradiol binding sites in the nuclear, cytoplasmic, and membrane fractions indicate the lens is able to respond to estrogens, even up to age 78, although fewer binding sites were detected in the postmenopausal women. Additionally, due to the importance of mouse models in estrogen action and lens research, lenses from intact female mice were also analyzed. Both the C57BL/6 and FVB/N mouse strains also possessed high affinity binding sites in all three lens fractions. Furthermore, transcripts for ERα, ERβ, and G protein-coupled estrogen receptor (GPER; previously called GPR30) that bind estradiol with high affinity were expressed in the human and mouse lenses. These data provide the first evidence of GPER expression in the lens. Its role, functions, and subcellular location are currently unknown, but a G-shift assay in the membrane fractions of human and mouse lenses did not show evidence that estradiol induced classic G protein-coupled receptor activation. All three receptor transcripts were also detected in the lens capsule region isolated from female C57BL/6 mice, which is mainly comprised of epithelial cells. In contrast, only ERα and GPER were expressed in the cortex/nuclear region, which is primarily composed of differentiating and organelle-free fiber cells. No significant differences in specific estradiol binding and receptor RNA expression were observed in the lenses between male and female C57BL/6 mice. These findings indicate that the lens is an estrogen target tissue in both sexes. The identification of GPER, in addition to ERα and ERβ, in the lens also adds to the complexity of possible estrogen responses in the lens. Accordingly, the protective effects of estrogen in women and animals may be mediated by all three estrogen receptors in the lens. In addition, the similarities in binding and receptor RNA expression in the lenses of both species suggest that mice can be used to model estrogen action in the human lens.

Selenium compound protects corneal epithelium against oxidative stress

The ocular surface is strongly affected by oxidative stress, and anti-oxidative systems are maintained in corneal epithelial cells and tear fluid. Dry eye is recognized as an oxidative stress-induced disease. Selenium compound eye drops are expected to be a candidate for the treatment of dry eye. We estimated the efficacy of several selenium compounds in the treatment of dry eye using a dry eye rat model. All of the studied selenium compounds were uptaken into corneal epithelial cells in vitro. However, when the selenium compounds were administered as eye drops in the dry eye rat model, most of the selenium compounds did not show effectiveness except for Se-lactoferrin. Se-lactoferrin is a lactoferrin that we prepared that binds selenium instead of iron. Se-lactoferrin eye drops suppressed the up-regulated expression of heme oxygenase-1, cyclooxygenase-2, matrix metallopeptidase-9, and interleukin-6 and also suppressed 8-OHdG production in the cornea induced by surgical removal of the lacrimal glands. Compared with Se-lactoferrin, apolactoferrin eye drops weakly improved dry eye in high dose. The effect of Se-lactoferrin eye drops on dry eye is possibly due to the effect of selenium and also the effect of apolactoferrin. Se-lactoferrin is a candidate for the treatment of dry eye via regulation of oxidative stress in the corneal epithelium.

Molecular basis for involvement of CYP1B1 in MYOC upregulation and its potential implication in glaucoma pathogenesis

CYP1B1 has been implicated in primary congenital glaucoma with autosomal recessive mode of inheritance. Mutations in CYP1B1 have also been reported in primary open angle glaucoma (POAG) cases and suggested to act as a modifier of the disease along with Myocilin (MYOC). Earlier reports suggest that over-expression of myocilin leads to POAG pathogenesis. Taken together, we propose a functional interaction between CYP1B1 and myocilin where 17β estradiol acts as a mediator. Therefore, we hypothesize that 17β estradiol can induce MYOC expression through the putative estrogen responsive elements (EREs) located in its promoter and CYP1B1 could manipulate MYOC expression by metabolizing 17β estradiol to 4-hydroxy estradiol, thus preventing it from binding to MYOC promoter. Hence any mutation in CYP1B1 that reduces its 17β estradiol metabolizing activity might lead to MYOC upregulation, which in turn might play a role in glaucoma pathogenesis. It was observed that 17β estradiol is present in Human Trabecular Meshwork cells (HTM) and Retinal Pigment Epithelial cells (RPE) by immunoflouresence and ELISA. Also, the expression of enzymes related to estrogen biosynthesis pathway was observed in both cell lines by RT-PCR. Subsequent evaluation of the EREs in the MYOC promoter by luciferase assay, with dose and time dependent treatment of 17β estradiol, showed that the EREs are indeed active. This observation was further validated by direct binding of estrogen receptors (ER) on EREs in MYOC promoter and subsequent upregulation in MYOC level in HTM cells on 17β estradiol treatment. Interestingly, CYP1B1 mutants with less than 10% enzymatic activity were found to increase the level of endogenous myocilin in HTM cells. Thus the experimental observations are consistent with our proposed hypothesis that mutant CYP1B1, lacking the 17β estradiol metabolizing activity, can cause MYOC upregulation, which might have a potential implication in glaucoma pathogenesis.

Is low dose of estrogen beneficial for prevention of glaucoma?

Glaucoma, as characterized by accelerated retinal ganglion cell (RGC) death and cupping of optic nerve head (ONH), is one of the leading causes of blindness worldwide. Elevated intraocular pressure (IOP) is generally considered as a major risk factor in the pathogenesis of glaucoma. Previous studies showed that glaucoma caused decrease in collagen and elastin density in several ocular tissues, such as lamina cribrosa, peripapillary sclera and cornea, and resulted in reduced elasticity and compliance of these tissues. It is known that estrogen has protective effects against glaucoma, yet the underlying mechanism still remains obscure. Prior researches have provided evidences showing that the estrogen receptors (ERs) express in a variety of the ocular tissues. Estrogen activates the synthesis of collagen fiber and improves the compliance of these tissues. This leads to a reasonable postulation that increased estrogen may result in a higher content of the collagen fibers and enhanced flexibility of the whole eye, which would therefore decrease IOP. Particularly, the increase in the amounts of collagen fibers at lamina cribrosa improves its compliance, which in turn relieves its compression on RGC axons. Therefore, even at the same IOP level, the softening of cribriform foramina yields a more flexible environment for the RGCs to survive. We therefore hypothesize that estrogen at proper dosage can be considered as a potential therapy for glaucoma since it is able to prevent the eye from glaucomatous damage and lower IOP, especially for those menopausal women with glaucoma.

Dose-dependent effects of androgens on the circadian timing system and its response to light

The hypothalamic suprachiasmatic nucleus (SCN) is the locus of a master clock that regulates circadian rhythms in physiology and behavior. Gonadectomy in male mice lengthens the period of circadian rhythms and increases the day-to-day variability of activity onset time. Both of these responses are rescued by the nonaromatizable androgen dihydrotestosterone. Androgen receptors (AR) are localized in SCN neurons that receive direct retinal input. To explore how androgens affect circadian clock function and its responsiveness to photic cues, we measured wheel-running behavior and SCN AR expression in intact, gonadectomized, and testosterone-replaced mice, held under various photic conditions. Gonadectomy lengthened circadian period in constant dim light but not in constant darkness. Increasing intensities of constant light parametrically increased circadian period, and this was potentiated at all intensities by gonadectomy. In contrast, gonadectomy did not alter light-induced pupil constriction, suggesting a nonretinal locus of hormone action. In hormone-replaced animals housed in constant darkness, T concentration was positively correlated with precision of activity onset and with SCN AR expression and negatively correlated with duration of activity. We infer the existence of two androgenic mechanisms: one modulates SCN responsiveness to light, and the second modulates SCN timekeeping and locomotor activity in a dose-dependent manner. Finally, the effects of androgens on period are a result of hormonal modulation of the SCN's response to photic input rather than to a change in the inherent period of oscillators in the absence of light.

Estrogen negatively regulates epithelial wound healing and protective lipid mediator circuits in the cornea

Estrogen receptors (ERs) are expressed in leukocytes and in every ocular tissue. However, sex-specific differences and the role of estradiol in ocular inflammatory-reparative responses are not well understood. We found that female mice exhibited delayed corneal epithelial wound closure and attenuated polymorphonuclear (PMN) leukocyte responses, a phenotype recapitulated by estradiol treatment both in vivo (topically in male mice) and in vitro (corneal epithelial cell wound healing). The cornea expresses 15-lipoxygenase (15-LOX) and receptors for lipoxin A(4) (LXA(4)), which have been implicated in an intrinsic lipid circuit that regulates corneal inflammation and wound healing. Delayed epithelial wound healing correlated with lower expression of 15-LOX in the regenerated epithelium of female mice. Estradiol in vitro and in vivo down-regulated epithelial 15-LOX expression and LXA(4) formation, while estradiol abrogation of epithelial wound healing was completely reversed by treatment with LXA(4). More important, ERβ and ERα selectively regulated epithelial wound healing, PMN cell recruitment, and activity of the intrinsic 15-LOX/LXA(4) circuit. Our results demonstrate for the first time a sex-specific difference in the corneal reparative response, which is mediated by ERβ and ERα selective regulation of the epithelial and PMN 15-LOX/LXA(4) circuit. These findings may provide novel insights into the etiology of sex-specific ocular inflammatory diseases.

Breast cancer medications and vision: effects of treatments for early-stage disease

This review concerns the effects on vision and the eye of medications prescribed at three phases of treatment for women with early-stage breast cancer (BC): (1) adjuvant cytotoxic chemotherapy, (2) adjuvant endocrine therapy, and (3) symptomatic relief. The most common side effects of cytotoxic chemotherapy are epiphora and ocular surface irritation, which can be caused by any of several different regimens. Most notably, the taxane docetaxel can lead to epiphora by inducing canalicular stenosis. The selective-estrogen-receptor-modulator (SERM) tamoxifen, long the gold-standard adjuvant-endocrine-therapy for women with hormone-receptor-positive BC, increases the risk of posterior subcapsular cataract. Tamoxifen also affects the optic nerve head more often than previously thought, apparently by causing subclinical swelling within the first 2 years of use for women older than ∼50 years. Tamoxifen retinopathy is rare, but it can cause foveal cystoid spaces that are revealed with spectral-domain optical coherence tomography (OCT) and that may increase the risk for macular holes. Tamoxifen often alters the perceived color of flashed lights detected via short-wavelength-sensitive (SWS) cone response isolated psychophysically; these altered perceptions may reflect a neural-response sluggishness that becomes evident at ∼2 years of use. The aromatase inhibitor (AI) anastrozole affects perception similarly, but in an age-dependent manner suggesting that the change of estrogen activity towards lower levels is more important than the low estrogen activity itself. Based on analysis of OCT retinal thickness data, it is likely that anastrozole increases the tractional force between the vitreous and retina. Consequently, AI users, myopic AI users particularly, might be at increased risk for traction-related vision loss. Because bisphosphonates are sometimes prescribed to redress AI-induced bone loss, clinicians should be aware of their potential to cause scleritis and uveitis occasionally. We conclude by suggesting some avenues for future research into the visual and ocular effects of AIs, particularly as relates to assessment of cognitive function.

Estradiol-dependent modulation of auditory processing and selectivity in songbirds

The steroid hormone estradiol plays an important role in reproductive development and behavior and modulates a wide array of physiological and cognitive processes. Recently, reports from several research groups have converged to show that estradiol also powerfully modulates sensory processing, specifically, the physiology of central auditory circuits in songbirds. These investigators have discovered that (1) behaviorally-relevant auditory experience rapidly increases estradiol levels in the auditory forebrain; (2) estradiol instantaneously enhances the responsiveness and coding efficiency of auditory neurons; (3) these changes are mediated by a non-genomic effect of brain-generated estradiol on the strength of inhibitory neurotransmission; and (4) estradiol regulates biochemical cascades that induce the expression of genes involved in synaptic plasticity. Together, these findings have established estradiol as a central regulator of auditory function and intensified the need to consider brain-based mechanisms, in addition to peripheral organ dysfunction, in hearing pathologies associated with estrogen deficiency.

Lipidomics of human Meibomian gland secretions: Chemistry, biophysics, and physiological role of Meibomian lipids

Human Meibomian gland secretions (MGS) are a complex mixture of diverse lipids that are produced by Meibomian glands that are located in the upper and the lower eyelids. During blinking, MGS are excreted onto the ocular surface, spread and mix with aqueous tears that are produced by lachrymal glands, and form an outermost part of an ocular structure called "the tear film" (TF). The main physiological role of TF is to protect delicate ocular structures (such as cornea and conjunctiva) from desiccating. Lipids that are produced by Meibomian glands are believed to "seal" the aqueous portion of TF by creating a hydrophobic barrier and, thus, retard evaporation of water from the ocular surface, which enhances the protective properties of TF. As lipids of MGS are interacting with underlying aqueous sublayer of TF, the chemical composition of MGS is critical for maintaining the overall stability of TF. There is a consensus that a small, but important part of Meibomian lipids, namely polar, or amphiphilic lipids, is of especial importance as it forms an intermediate layer between the aqueous layer of TF and its upper (and much thicker) lipid layer formed mostly of very nonpolar lipids, such as wax esters and cholesteryl esters. The purpose of this review is to summarize the current knowledge on the lipidomics of human MGS, including the discussions of the most effective modern analytical techniques, chemical composition of MGS, biophysical properties of Meibomian lipid films, and their relevance for the physiology of TF. Previously published results obtained in numerous laboratories, as well as novel data generated in the author's laboratory, are discussed. It is concluded that despite a substantial progress in the area of Meibomian glands lipidomics, there are large areas of uncertainty that need to be addressed in future experiments.

Finasteride for chronic central serous chorioretinopathy

PURPOSE

To evaluate the safety and efficacy of finasteride, an inhibitor of dihydrotestosterone synthesis, in the treatment of chronic central serous chorioretinopathy.

METHODS

Five patients with chronic central serous chorioretinopathy were prospectively enrolled in this pilot study. Patients were administered finasteride (5 mg) daily for 3 months, after which study medication was withheld and patients were observed for 3 months. Main outcome measures included best-corrected visual acuity, central subfield macular thickness, and subretinal fluid volume as assessed by optical coherence tomography. Serum dihydrotestosterone, serum testosterone, and urinary cortisol were also measured.

RESULTS

There was no change in mean best-corrected visual acuity. Mean center-subfield macular thickness and subretinal fluid volume reached a nadir at 3 months and rose to levels that were below baseline by 6 months. The changes in both optical coherence tomography parameters paralleled those in serum dihydrotestosterone level. In four patients, center-subfield macular thickness and/or subretinal fluid volume increased after discontinuation of finasteride. In the remaining patient, both optical coherence tomography parameters normalized with finasteride and remained stable when the study medication was discontinued.

CONCLUSION

Finasteride may represent a novel medical treatment for chronic central serous chorioretinopathy. Larger controlled clinical trials are needed to further assess the efficacy of finasteride for the treatment of central serous chorioretinopathy.

[Central corneal thickness in a healthy Spanish population]

OBJECTIVE

To study the central corneal thickness of a Spanish population group and determine the influence of age, gender, axial length and refractive error on central corneal thickness (CCT) values.

METHODS

An observational, cross-sectional, double masked study was conducted on 357 eyes of consecutive Caucasian patients without ophthalmic disease. They were distributed according to age, and high refractive defects were excluded. Ultrasonic pachymetry and a complete eye examination were performed on all patients. The relationship between the central corneal thickness values and variables of age, refractive error, axial length and gender was assessed.

RESULTS

The mean central corneal thickness was 548.21 μm with a standard deviation (SD) of 30.7 μm (range 464 to 633 μm). The normal central corneal thickness value of the population studied was 486.81 to 609.61 μm (95% confidence interval). No statistical association was found between central corneal thickness values and variables of age, refractive error, axial length and gender.

CONCLUSIONS

Central corneal thickness varies according to race. We have analysed, for the first time, normal central corneal thickness values of a healthy Spanish population.

Immunohistochemical detection of estrogen and progesterone receptors in the human lacrimal gland

The nature and extent of estrogen and progesterone action on the lacrimal gland is not known, and neither are the targets for their action. Immunohistochemical detection of estrogen and progesterone receptors in the human lacrimal glands in both sexes in different age groups was performed in this study. Twenty human lacrimal glands from autopsies were analyzed by the immunohistochemical method of cell counting and the ?? test. Estrogen and progesterone receptors were detected in the lacrimal glands of both sexes with significantly higher total and average cell counts in females (p<0,001). Estrogen and progesterone receptors are present in human lacrimal glands with age and gender dependent expression.

The significance of anabolic androgenic steroids in a Swedish prison population

Use of anabolic androgenic steroids (AAS) has been associated with adverse psychiatric effect, violent behavior, and criminality. The aim of this study was to further investigate the motives for and consequences of AAS use, with focus on violent and antisocial behavior. Fifty-nine prisoners were interviewed on their use of AAS, and their history was mapped with Addiction Severity Index interviews. Of these prisoners, 56% admitted previous use of AAS, of whom 24% declared to have committed violent crimes in connection with use of AAS. However, the only significant difference between users and nonusers with regard to criminal history when measured with the Addiction Severity Index was that the AAS users more often stated that they had been prosecuted for crimes labeled as "other crimes," which did not include violent crimes. The reported side effects of AAS corresponded well to those previously reported. These results indicate that use of AAS is common among Swedish prisoners and that the motives and consequences of such use are similar to what has been observed in other AAS-using populations. Furthermore, this study supports earlier notions that misuse of AAS might cause violent behavior, but only in certain individuals and mainly in combination with other substances.

Effects of extract of Buddleja officinalis eye drops on androgen receptors of lacrimal gland cells of castrated rats with dry eye

AIM

To evaluate the effects of the extract of Buddleja officinalis eye drops in basic tears secretory volume, tear film stability, expression of androgen receptors (AR) in castrated rats with dry eye, and to investigate the therapeutic effects of the extract of Buddleja officinalis on dry eye caused by gonadal hormones level imbalance.

METHODS

Forty-five Wistar masculinity rats were divided at random into nine groups, including normal groups (A1, A2 and A3); model groups (B1, B2 and B3); therapy groups with extract of Buddleja officinalis eye drops (C1, C2 and C3). The "1" stood for being fed for 1 month, and "2" for 2 months, and "3" for 3 months. The dry eye model was established with orchiectomy on groups B and C. Group C was treated with Buddleja officinalis extract eye drops for one month. All rats were checked with Schirmer I test (SIT) and tear film break-up time (BUT). Expression of AR was analyzed by flow cytometer (FCM).

RESULTS

The SIT value of group C was significantly higher than that of group B (P<0.01) and the BUT value of group C was significantly longer than that of group B (P<0.01), which indicated the eye drop could significantly keep basic tears secretory volume and tear film stability. And the expression of AR of group C was much higher than that of group B, which showed that available composition of the eye drops maybe display androgen-like activity.

CONCLUSION

The main components of the extract of Buddleja officinalis is the flavonoids that can significantly inhibit happening of dry eye of rat after androgen level lowered. Its mechanism is like androgen's and it can display androgen-like activity to keep basic tears secretory volume and tear film stability.

Human lipocalin-1 association with 3H-testosterone and 3H-estradiol

PURPOSE

Topical androgens and estrogens have been studied for use in treating ocular conditions such as dry eye. The aim of this study was to identify proteins from normal human tears that associated with exogenously added sex steroid hormones. One of the major proteins in ocular tears is lipocalin-1. It binds a variety of lipids and other hydrophobic molecules and is proposed to function as a carrier protein or a lipid scavenger.

METHODS

Normal human tears were incubated with (3)H-testosterone or (3)H-estradiol. Labeled tear proteins were separated on a Q Sepharose Fast Flow (QFF) Hi Trap strong anion exchange column with a step gradient of NaCl. (3)H-testosterone or (3)H-estradiol was measured in aliquots of eluted fractions using scintillation counts, and the remainder of each sample was gel electrophoresed and silver stained. In separate experiments, (3)H-steroid-labeled tear proteins were electrophoresed in 15% polyacrylamide gels and excised from the gels. Tritium content of the proteins was measured in a scintillation counter. Immunoblots with antibodies to lipocalin-1 verified the migration of lipocalin-1 in the gels.

RESULTS

(3)H-steroid labeled tear proteins were found in the 0.15 M NaCl fractions of QFF strong anion exchange columns. 18 kD lipocalin-1 (among other tear proteins) eluted in the 0.15 M NaCl fraction. Excision of labeled tear proteins from 15% polyacrylamide gels indicated that radioactive label was associated with an 18 kD protein. Immunoblots verified that lipocalin-1 migrated as an 18 kD protein.

CONCLUSIONS

The sex steroid hormones testosterone and estradiol associated with 18 kD lipocalin-1 in human tears.

[Sex hormones and dry eye]

Among ophthalmic diseases dry eye in its various forms, represents an entity with one of the highest prevalences and at the same time the lowest chance for causal therapy. Since some years there is growing evidence that sex hormones play a key role in the formation and course of the disease and thus provide potentially promising approaches for therapy. The objective of this article is to briefly outline current scientific knowledge on the relationship between androgens, estrogens,and progesterones on the one hand and the lacrimal gland and Meibomian glands respectively.

Influence of bilateral medial collateral ligament injury on mRNA expression in distal corneal tissues of control and ovariohysterectomized rabbits

PURPOSE

Corneal tissues are reported to be impacted by physiological changes (eg, menopause), systemic autoimmune diseases, and osteoarthritic-like conditions. In this study, changes in specific mRNA levels in the cornea after a ligament injury in normal and rabbits subjected to surgical menopause were examined.

METHODS

Skeletally mature female rabbits were either sham-operated (control) or were subjected to surgical menopause (OVX). Eight weeks post-OVX, subsets of control and OVX animals were subjected to bilateral injuries to their medial collateral ligaments (MCL) of the knee, and 6 and 14 weeks postinjury, corneal tissues were harvested. Using reverse transcriptase-polymerase chain reaction, mRNA levels for several relevant molecules, including matrix molecules, growth factors, cytokines, proteinases, and hormone receptors, were assessed.

RESULTS

mRNA levels for estrogen receptor, decorin, collagens, several growth factors, and inflammatory cytokines decreased in central corneal tissue 6 weeks after distal MCL injury in control animals. The central corneal tissues of animals subjected to OVX alone also exhibited decreases in mRNA levels for a similar set of molecules. When OVX animals were further subjected to MCL injury, the mRNA levels for many of these molecules did not vary from those in the uninjured OVX group. Interestingly, mRNA levels for most molecules were still altered 14 weeks post-MCL injury in the control and OVX animals, a time when the MCL has healed.

CONCLUSIONS

Corneal tissues respond to changes resulting from OVX and/or injury. OVX combined with a ligament injury does not appear to have an additive impact on corneal mRNA levels for most of the molecules assessed.

[Meibomian glands. Part I: anatomy, embryology and histology of the Meibomian glands]

The Meibomian glands are large sebaceous glands that are located as separate gland strands in parallel arrangement within the tarsal plates of the eyelids. Their oily product (meibum) is secreted by a holocrine mechanism during which the secretory cells (meibocytes) are completely transformed into the meibum after synthesis and accumulation of lipids. After production in the gland acini, meibum is transported through the ductal system via the connecting duct (ductule) and the central duct towards the orifice at the free lid margin close to the inner lid border. The embryological development of the Meibomian glands takes place during the differentiation of the eyelids in the sealing phase of the eyelids. They are not directly associated with hair follicles but share important similarities in embryology, structure and keratinization potency with the cilia. Similar to the sebaceous glands Meibomian glands are regulated via sex hormones and androgens have a supporting function whereas estrogens act antagonistically. However, in contrast to other sebaceous glands they also have a distinct innervation, apart from sympathetic and sensory primarily by parasympathetic fibers that share the innervation pattern of the lacrimal glands. The anatomy, embryology and histology of the Meibomian glands are explained here, mainly with respect to humans, in an extensive review.

Effect of Buddleia flavonoids drug-containing plasma on the expression of STAT1 phosphoprotein in lacrimal gland epithelial cells in vitro

AIM

To explore the effect of Buddleia flavonoids drug-containing plasma and androgen receptor (AR) blocker on the expression of STAT1 phosphoprotein.

METHODS

In vitro lacrimal gland epithelial cells were cultivated with H(2)O(2) to establish the dry eye apoptosis state. Blank plasma group, Buddleia officinalis plasma total flavonoids interfere with drug-containing group, and the intervention group of testosterone propionate were set. The expressions of STAT1 phosphoprotein of each group were observed by Western blot. AR blocker flutamide was used to explore the intended androgen effect of Buddleia flavonoids.

RESULTS

After the intervention of drug-containing plasma, the expression of STAT1 phosphoprotein in Buddleja officinalis drug-containing plasma intervention group (0.353±0.494) and testosterone propionate intervention group (0.502±0.036) were enhanced and the differences between the two groups were significant (P<0.01). After using AR blocker, the expression of STAT1 phosphoprotein in each group (0.268±0.061, 0.283±0.106, 0.213±0.071) had no difference.

CONCLUSION

Buddleja officinalis drug-containing plasma total flavonoids can promote the expression of STAT1 phosphorylation.

Effects of extract of Buddleja officinalis on partial inflammation of lacrimal gland in castrated rabbits with dry eye

AIM

To assess the effects of extract of Buddleja officinalis on tear secretion volume, tear film stability, expressions of TGF-β1, IL-1β, TNF-α in lacrimal gland of castrated rabbits with dry eye.

METHODS

A total of 30 victory rabbits were divided averagely into normal group(A), model group(B), therapy group with low dose extract of Buddleja officinalis (C), therapy group with high dose extract of Buddleja officinalis (D) and therapy group with genistein (E). The dry eye model was established with orchiectomy on Group B, C, D, E. Group C, D, E were administered intragastrically with corresponding dose extract of Buddleja officinalis or genistein for 30 days. All rabbits were detected with SIT. TGF-β1, IL-1β, TNF-α were detected with immunohistochemistry and the ultrastructure of lacrimal gland was observed under transmission electron microscope.

RESULTS

The SIT value of group C, D, E were respectively 13.167±4.957, 14.667±5.279, 8.667±0.516, obviously higher than that of group B 5.667±2.338 (P<0.01). The positive expression of IL-1β in acinar cell and glandular tube cell of group C, D were 0.470±0.048, 0.510±0.088, obviously lower than that of group B 0.770±0.118 (P<0.01). The positive expression of TNF-α of group C, D were 0.498±0.156, 0.435±0.069, obviously lower than that of group B 0.769±0.095 too (P<0.01). The positive expression of TGF-β1 of group C, D were 0.406±0.171, 0.497±0.147, obviously higher than that of group B 0.222±0.113(P<0.01). Any result of group C, D was positive compared with that of group E (P <0.05). Ultrastructure of the lacrimal gland of group C, D, E was well preserved, especially in D group it was remarkable.

CONCLUSION

The extract of Buddleja officinalis can adjust lacrimal gland partial inflammation of dry eye.

Experimental use of estriol for visualizing the vitreous body in the anterior chamber after posterior capsule rupture in animal models

PURPOSE

To compare the efficacy and safety of estriol and triamcinolone acetonide suspensions in visualizing the prolapsed vitreous body in the anterior chamber after posterior capsule rupture in animal models.

SETTING

Tsukuba University Institute of Clinical Medicine, Ibaraki, Japan.

METHODS

To evaluate efficacy, triamcinolone acetonide or estriol suspension was injected into the anterior chambers of porcine eyes after intentional posterior capsule rupture. To evaluate safety, triamcinolone acetonide 5.0 mg or estriol in 0.1 mL suspension was injected into the anterior chamber of New Zealand white rabbits. Slitlamp examinations, intraocular pressure (IOP), corneal endothelial cell density (ECD) measurements, and histologic examinations were performed up to 28 days after the injection.

RESULTS

Triamcinolone acetonide and estriol were equally effective in allowing visualization of the prolapsed vitreous body in the anterior chamber. The granules of triamcinolone acetonide or estriol disappeared 1 day after the injection and did not affect the IOP or corneal ECD. No statistically significant histological changes were observed in the eyes 28 days after the injection of triamcinolone acetonide or estriol.

CONCLUSIONS

Estriol was effective for the visualization of the prolapsed vitreous body in the anterior chamber after posterior capsule rupture. In experimental models, no significant side effects were observed after the injection of estriol in the anterior chamber. Results suggest that estriol is an alternative reagent for visualizing the vitreous body, especially in steroid responders, because it has no glucocorticoid or mineralocorticoid activity.

Progesterone potentiates IP(3)-mediated calcium signaling through Akt/PKB

The activity of cells critically depends on the control of their cytosolic free calcium ion (Ca(2+)) concentration. The objective of the present study was to identify mechanisms of action underlying the control of the gain of intracellular Ca(2+) release by circulating gonadal steroid hormones. Acute stimulation of isolated neurons with progesterone led to IP(3)R-mediated Ca(2+) transients that depend on the activation of the PI3 kinase/Akt/PKB signaling pathway. These results were confirmed at the molecular level and phosphorylation of IP(3)R type 1 by Akt/PKB was identified as the mechanism of action. Hence, it is likely that circulating gonadal steroid hormones control neuronal activity including phosporylation status through receptor- and kinase-mediated signaling. With a direct control of the gain of the Ca(2+) second messenger system as a signaling gatekeeper for neuronal activity the present study identifies a novel pathway for interaction of the endocrine and central nervous system.