Estrogen masculinizes neural pathways and sex-specific behaviors.

Sex hormones are essential for neural circuit development and sex-specific behaviors. Male behaviors require both testosterone and estrogen, but it is unclear how the two hormonal pathways intersect. Circulating testosterone activates the androgen receptor (AR) and is also converted into estrogen in the brain via aromatase. We demonstrate extensive sexual dimorphism in the number and projections of aromatase-expressing neurons. The masculinization of these cells is independent of AR but can be induced in females by either testosterone or estrogen, indicating a role for aromatase in sexual differentiation of these neurons. We provide evidence suggesting that aromatase is also important in activating male-specific aggression and urine marking because these behaviors can be elicited by testosterone in males mutant for AR and in females subjected to neonatal estrogen exposure. Our results suggest that aromatization of testosterone into estrogen is important for the development and activation of neural circuits that control male territorial behaviors.

[A Case of a Two-Stage Robotic-Assisted Surgery for a Neuroendocrine Tumor of the Pancreatic Tail with Simultaneous Single Liver Metastasis].

As medical insurance coverage for robotic surgery has been expanded in the field of gastrointestinal surgery in Japan, the number of cases undergoing robotic surgery for hepato-biliary-pancreatic disease has been increasing. Therefore, cases with malignant tumors and metastatic lesions tend to undergo robotic operation for both primary tumors and metastases. Herein, we report a case of neuroendocrine tumor(NET)in the pancreatic tail with simultaneous single liver metastasis, which was treated with two-stage robotic-assisted surgery. A 67-year-old female underwent a computed tomography scan and a hypovascularized tumor in the pancreatic tail region and liver was found. A biopsy of the pancreatic tumor by endoscopic ultrasound-guided fine needle aspiration demonstrated a NET G1-2. The liver lesion was diagnosed as a metastatic tumor, considering the other examinations. The patient underwent a robotic distal pancreatectomy(RDP)and was histopathologically diagnosed as NET G2. Sixty-three days after the RDP, a two-stage partial liver resection for the metastatic tumor was performed under robotic assistance. Curative resection was achieved through two-stage robot-assisted surgery, there were no postoperative complications.

[Curative Resection after Chemotherapy for Advanced Extensive Cholangiocarcinoma-A Case Report].

A 73-year-old, male patient presented with the chief complaint of epigastric pain and received the diagnosis of extensive cholangiocarcinoma after a close examination. Extensive extension of the malignancy into the right and left hepatic ducts precluded a curative resection, and the patient received GC therapy. After 11 courses of GC over about 1 year, no new lesions or tumor progression was observed, and a bile duct mapping biopsy was performed to investigate the possibility of resection conversion. The results showed a marked decrease in atypia, and reactive atypia was diagnosed. A pancreaticoduodenectomy was performed, and histopathologically negative margins were obtained. The response to treatment was Grade Ⅱa according to the Evans classification. At 23 months after the start of treatment and 12 months after surgery, the patient is recurrence-free without adjuvant chemotherapy. Although the evidence for conversion surgery for biliary tract cancer has not been established, the long-term outcomes may be favorable.

Aromatase controls Sjögren syndrome-like lesions through monocyte chemotactic protein-1 in target organ and adipose tissue-associated macrophages.

Several autoimmune diseases are known to develop in postmenopausal women. However, the mechanism by which estrogen deficiency influences autoimmunity is unknown. Aromatase is an enzyme that converts androgens to estrogens. Herein, we used female aromatase gene knockout (ArKO) mice as a model of estrogen deficiency to investigate the molecular mechanism that underlies the onset and development of autoimmunity. Histological analyses showed that inflammatory lesions in the lacrimal and salivary glands of ArKO mice increased with age. Adoptive transfer of spleen cells or bone marrow cells from ArKO mice into recombination activating gene 2 knockout mice failed to induce the autoimmune lesions. Expression of mRNA encoding proinflammatory cytokines and monocyte chemotactic protein-1 increased in white adipose tissue of ArKO mice and was significantly higher than that in wild-type mice. Moreover, an increased number of inflammatory M1 macrophages was observed in white adipose tissue of ArKO mice. A significantly increased monocyte chemotactic protein-1 mRNA expression of the salivary gland tissue in ArKO was found together with adiposity. Furthermore, the autoimmune lesions in a murine model of Sjögren syndrome were exacerbated by administration of an aromatase inhibitor. These results suggest that aromatase may play a key role in the pathogenesis of Sjögren syndrome-like lesions by controlling the target organ and adipose tissue-associated macrophage.

Visualization of subcapsular hepatic malignancy by indocyanine-green fluorescence imaging during laparoscopic hepatectomy.

BACKGROUND: Although laparoscopic hepatectomy has increasingly been used to treat cancers in the liver, the accuracy of intraoperative diagnosis may be inferior to that of open surgery because the ability to visualize and palpate the liver surface during laparoscopy is relatively limited. Fluorescence imaging has the potential to provide a simple compensatory diagnostic tool for identification of cancers in the liver during laparoscopic hepatectomy. METHODS: In 17 patients who were to undergo laparoscopic hepatectomy, 0.5 mg/kg body weight of indocyanine green (ICG) was administered intravenously within the 2 weeks prior to surgery. Intraoperatively, a laparoscopic fluorescence imaging system obtained fluorescence images of its surfaces during mobilization of the liver. RESULTS: In all, 16 hepatocellular carcinomas (HCCs) and 16 liver metastases (LMs) were resected. Of these, laparoscopic ICG fluorescence imaging identified 12 HCCs (75%) and 11 LMs (69%) on the liver surfaces distributed over Couinaud's segments 1-8, including the 17 tumors that had not been identified by visual inspections of normal color images. The 23 tumors that were identified by fluorescence imaging were located closer to the liver surfaces than another nine tumors that were not identified by fluorescence imaging (median [range] depth 1 [0-5] vs. 11 [8-30] mm; p < 0.001). CONCLUSIONS: Like palpation during open hepatectomy, laparoscopic ICG fluorescence imaging enables real-time identification of subcapsular liver cancers, thus facilitating estimation of the required extent of hepatic mobilization and determination of the location of an appropriate hepatic transection line.

Estradiol promotes purkinje dendritic growth, spinogenesis, and synaptogenesis during neonatal life by inducing the expression of BDNF.

Neurosteroids are synthesized de novo from cholesterol in the brain. In rodents, the Purkinje cell actively produces several kinds of neurosteroids including estradiol during neonatal life, when cerebellar neuronal circuit formation occurs. Estradiol may be involved in cerebellar neuronal circuit formation through promoting neuronal growth and synaptic contact, because the Purkinje cell expresses estrogen receptor-ß. To test this hypothesis, in this study we examined the effect of estradiol on dendritic growth, spinogenesis, and synaptogenesis in the Purkinje cell using neonatal wild-type (WT) mice or cytochrome P450 aromatase knock-out (ArKO) mice. Administration of estradiol to neonatal WT or ArKO mice increased dendritic growth, spinogenesis, and synaptogenesis in the Purkinje cell. In contrast, WT mice treated with tamoxifen, an ER antagonist, or ArKO mice exhibited decreased Purkinje dendritic growth, spinogenesis, and synaptogenesis at the same neonatal period. Estrogen administration to neonatal WT or ArKO mice increased the expression of brain-derived neurotrophic factor (BDNF) in the cerebellum, whereas tamoxifen decreased the BDNF level in WT mice similar to ArKO mice. BDNF administration to tamoxifen-treated WT mice increased Purkinje dendritic growth. These results indicate that estradiol induces dendritic growth, spinogenesis, and synaptogenesis in the developing Purkinje cell via BDNF action during neonatal life.

Protective effect of Brazilian propolis against hepatic oxidative damage in rats with water-immersion restraint stress.

In the present study we examined the protective effect of Brazilian propolis against hepatic oxidative damage in rats with water-immersion restraint stress (WIRS) in comparison with that of vitamin E (VE). Fasted rats orally received Brazilian green propolis ethanol extract (BPEE; 10, 50 or 100 mg/kg), VE (250 mg/kg) or vehicle at 30 min before the onset of WIRS. Exposure of vehicle-treated rats to 6 h of WIRS caused liver cell damage, judging from the levels of serum alanine aminotransferase and aspartate aminotransferease, increased hepatic lipid peroxide, NO(x) contents and myeloperoxidase activity, and decreased hepatic non-protein SH, ascorbic acid contents and superoxide dismutase activity. Preadministration of BPEE (50 or 100 mg/kg) or VE to the stressed rats protected against the hepatic damage and attenuated the increased hepatic lipid peroxide and NO(x) contents and myeloperoxidase activity and the decreased hepatic non-protein SH and ascorbic acid contents and superoxide dismutase activity. These protective effects of BPEE (50 mg/kg) were greater than those of BPEE (100 mg/kg) and were almost equal to those of VE. These results indicate that BPEE protects against hepatic oxidative damage in rats exposed to WIRS possibly through its antioxidant and antiinflammatory properties such as VE.

Genetic targeting aromatase in male amyloid precursor protein transgenic mice down-regulates beta-secretase (BACE1) and prevents Alzheimer-like pathology and cognitive impairment.

As brain testosterone plays both androgenic and estrogenic actions due to its conversion into estrogen via aromatase naturally, it is unclear that the age-related reduction of testosterone increased risk of Alzheimer's disease (AD) in men is mediated through androgen alone or both androgen and estrogen mechanisms. Our previous studies using a gene-based approach in mouse model to block the conversion of testosterone into estrogen (aromatase gene knock-out, ArKO), found a depletion of estrogen and increase in testosterone endogenously in males. Here, we use crossing the ArKO mice with APP23 transgenic mice, a mouse model of AD, to produce APP23/Ar(+/-) mice to study the estrogen-independent effect of testosterone on AD. We found a significant reduction in brain plaque formation, improved cognitive function and increase NEP activity in male APP23/Ar(+/-) mice compared with age-matched male APP23 controls. In addition, we found, for the first time, a reduction of beta-secretase (BACE1) enzyme activity, mRNA level and protein expression in the male APP23/Ar(+/-) mice, suggesting that endogenous testosterone, independent from estrogen, may protect against AD in males via two major mechanisms, downregulation of BACE1 activities at transcriptional level to reduce beta amyloid production and upregulation of NEP activities to enhance bate amyloid degradation.

Sex steroid hormones in pairs of tumor and serum from breast cancer patients and pathobiological role of androstene-3ß, 17ß-diol.

Estrogens play an important role in the pathobiology of breast cancer. In postmenopausal women, peripheral synthesis of estrogens from adrenal/ovarian androgens, dehydroepiandrosterone (DHEA) or androstenedione (Adione), by estrogen-metabolizing enzymes is important. Besides estrone (E1) and estradiol (E2), androgen metabolites, such as androstene-3ß, 17ß-diol (Aenediol) or 5α-androstane-3ß, 17ß-diol (Aanediol), are known to have estrogenic functions, although they have been studied much less in breast cancer. To precisely elucidate steroid metabolism in breast cancer patients and to identify the pathobiological role of estrogenic androgen metabolites, concentrations of DHEA, Adione, Aenediol, Aanediol, E1, and E2 in pairs of serum and tumor tissue from patients with primary breast cancer were measured by liquid chromatography-tandem mass spectrometry. Cell proliferation assays using Aenediol were performed for four breast cancer cell lines. Serous E2 concentration was extremely low in postmenopausal women; however, a marked increase in tumor tissue was observed in hormone receptor-positive cases. E1 concentration, in contrast, was sustained at a higher level, even in postmenopausal serum, and did not increase in tumor tissue irrespective of the hormone receptor status. Dehydroepiandrosterone was most abundant in all samples, and exhibited a similar pattern as Adione and Aenediol. 5α-Androstane-3ß, 17ß-diol was undetectable in most samples. Androstene-3ß, 17ß-diol proliferated estrogen receptor-apositive breast cancer cells in the absence of E2. The intratumoral increase of E2, but not E1, in hormone receptor-positive postmenopausal breast cancer tissue, as well as the proliferative role of Aenediol, was elucidated.

Application of fluorescent cholangiography to single-incision laparoscopic cholecystectomy.

BACKGROUND: Although the use of single-incision laparoscopic cholecystectomy (SILC) is spreading rapidly, this technique has disadvantages. It does not allow for sufficient surgical views to be obtained or for intraoperative radiographic cholangiography to be performed. Fluorescent cholangiography using a preoperative intravenous injection of indocyanine green (ICG) may be useful for identifying the biliary tract during both SILC and conventional laparoscopic cholecystectomy. METHODS: For seven patients undergoing SILC, 1 ml of ICG (2.5 mg) was administered by intravenous injection before the surgery. The prototype fluorescent imaging system consisted of a xenon light source and a 30° laparoscope (diameter, 10 mm) equipped with a charge-coupled device camera capable of filtering out light with wavelengths shorter than 810 nm. The laparoscope was introduced through an umbilical trocar. Fluorescent cholangiography then was performed by changing the color images to fluorescent images using a foot switch during dissection of the triangle of Calot. RESULTS: Fluorescent cholangiography identified the confluence between the cystic duct and the common hepatic duct in all seven patients before and throughout the dissection of the triangle of Calot. The interval from the injection of ICG to the first obtained fluorescent cholangiography before dissection of the triangle of Calot ranged from 35 to 75 min. CONCLUSIONS: Fluorescent cholangiography enabled real-time identification of the extrahepatic bile ducts during SILC without necessitating catheterization of the bile duct. Such properties of fluorescent cholangiography are expected to be helpful for ensuring the safety of SILC and expanding the indications for the procedure.

Transcriptional regulation of CYP19 by cohesin-mediated chromosome tethering in human granulosa cells.

Human CYP19 spans a region of chromosome 15 of approximately 130 kb and encodes aromatase, an enzyme required for estrogen synthesis. In the human granulosa cell-line KGN, there are seven open chromatin regions within the CYP19 locus. In this study, we demonstrate that two of these regions ~40 kb upstream and ~15 kb downstream of the CYP19 promoter are cohesin-loading sites, physically interacting with the promoter to negatively and positively regulate transcription, respectively. These observations suggest that CYP19 expression is controlled by a balance between the upstream silencer and downstream enhancer. When cohesin is depleted, CYP19 expression is elevated since the silencer is 2.5-fold further from the promoter than the enhancer and most likely depends on cohesin-mediated tethering to influence expression.

ARP-1 Regulates the Transcriptional Activity of the Aromatase Gene in the Mouse Brain.

An important function of aromatase in the brain is conversion of testosterone secreted from the testis into estradiol. Estradiol produced in the brain is thought to be deeply involved in the formation of sexually dimorphic nuclei and sexual behavior as a neurosteroid. We analyzed the brain-specific promoter to elucidate the control mechanisms of brain aromatase expression that may be highly involved in sexual differentiation of the brain. The 202-bp upstream region of the brain-specific exon 1 has three types of cis-acting elements, aro-AI, AII, and B. We isolated ARP-1 as an aro-AII-binding protein by yeast one-hybrid screening from a cDNA library of mouse fetal brains. ARP-1 is a member of the nuclear receptor superfamily and functions as an orphan-type transcription factor. ARP-1 protein synthesized in vitro showed the same binding property to the aro-AII site as nuclear extract from fetal brains. To determine how the promoter is involved in brain-specific transcription of the aromatase gene, we first detected the in vivo occupancy of the aro-AII site by ARP-1 using chromatin immunoprecipitation assays. Diencephalic regions of fetal brains at embryonic day 16 were analyzed, which revealed ARP-1 recruitment to the aro-AII site. To analyze the effects of ARP-1 on transcriptional regulation of the brain-specific aromatase promoter, a luciferase reporter plasmid driven by the brain-specific promoter was transfected into CV-1 cells together with a plasmid expressing ARP-1 protein. These analyses revealed that ARP-1 induced promoter activity in a dose-dependent manner. Furthermore, to determine whether ARP-1 is required for aromatase expression in neurons, ARP-1 knockdown was conducted in neuronal cell primary culture. Knockdown of ARP-1 significantly suppressed the increase in aromatase mRNA observed in cultured neurons. These results indicate that ARP-1 is involved in the transcriptional regulation of the brain-specific promoter of the aromatase gene.

Upregulation of CIP2A in estrogen depletion-resistant breast cancer cells treated with low-dose everolimus.

Everolimus (EVE), an inhibitor of mammalian target of rapamycin, is an emerging second-line therapeutic option for hormone therapy-resistant breast cancers. However, some patients do not respond to EVE, whereas in others it exacerbates the disease. Cellular inhibitor of protein phosphatase 2A (CIP2A) is a human oncoprotein that can promote cancer cell growth and apoptosis resistance. Although CIP2A is upregulated in hormone-related cancers, such as breast cancer, little is known about potential anti-tumor effects of downregulating CIP2A. As a model to study the resistance of breast cancer cells to hormone treatment, we previously established clones of long-term estrogen depletion-resistant MCF-7 (LTED) cells. Here, we selected three clones highly responsive to EVE and three clones poorly responsive to EVE. When cells were treated with EVE, CIP2A mRNA expression was decreased in highly responsive EVE clones (DC-cells) whereas it was increased in poorly responsive EVE clones (IC-cells). Using Kaplan-Meier survival plots, we report that high expression of CIP2A was associated with significantly reduced overall survival in patients with luminal A breast cancer. In IC-cells, cell growth was enhanced upon EVE treatment whereas an EVE range of 0.1-100 nm decreased growth in DC-cells. The mRNA expression of genes involved in epithelial-mesenchymal transition (EMT) such as CDH1, CLDN3, and CK19 was significantly decreased in IC-cells, but remained unchanged in DC-cells. These findings highlight a relationship between CIP2A and EMT in the intrinsic resistance of hormone therapy-resistant breast cancers to EVE.

The ABO Blood Group Impacts the Survival of Patients Undergoing Pancreatoduodenectomy for Biliary Tract Cancer.

BACKGROUND/AIM: Although ABO blood group has been reported to be associated with the outcome of patients with pancreatic cancer, little is known about its impact on patients with biliary tract cancer (BTC). We evaluated the prognostic relevance of ABO blood group in patients who had undergone resection of BTC. PATIENTS AND METHODS: A total of 154 patients with BTC undergoing pancreatoduodenectomy were retrospectively reviewed. Associations between ABO blood group and patient survival were evaluated by univariate and multivariate analysis. RESULTS: The 5-year overall survival rate was higher in group O patients (n=46) than in other blood group patients (n=108) (65.8% vs. 47%, p=0.005). Multivariate analysis revealed that a non-O blood group was an independent risk factor for poor survival (p=0.021). CONCLUSION: ABO blood group is associated with the prognosis of patients with resected BTC; group O patients have a better outcome.

Alternative use of multiple exons 1 of aromatase gene in cancerous and normal breast tissues from women over the age of 80 years.

INTRODUCTION: Peripherally localized aromatase, which converts circulating androgens into estrogens, is important in the pathogenesis of postmenopausal breast carcinomas. We have previously shown that aromatase mRNA levels are higher in elderly breast carcinomas (EldCa) than breast carcinomas of the control group (ContCa) or normal breast tissues. Aromatase expression has been reported to be regulated through the alternative use of multiple exons 1 (exons 1a-1f and so on); however, the preferential usage of exons 1 in elderly breast tissue has never been systematically examined. In order to properly treat and protect against EldCa, the regulation mechanism of aromatase expression in elderly breast tissues should be elucidated. The aim of the present study is to elucidate whether there are any specific patterns in use of multiple exons 1 in elderly breast tissue. METHODS: Usage of multiple exons 1 of the aromatase gene and mRNA levels of aromatase were examined by reverse transcription-polymerase chain reaction analysis in breast tissues of 38 elderly patients with breast cancer (age 80-99), and the results were compared with those in 35 patients of the control group (age 37-70). One-factor analysis of variance and the Scheffé test were used for the comparison of aromatase mRNA levels. Patterns of preferential utilization of multiple exons 1 of the aromatase gene were compared by chi2 test for independence or Fisher exact test for independence using a contingency table. RESULTS: Exon 1d was utilized much more frequently in elderly tissue than in the control group irrespective of cancerous or normal tissue (EldCa, 36/38, 95% versus ContCa, 7/35, 20%, P < 0.0001; normal tissue of the elderly, EldNorm, 30/34, 88% versus normal tissue of controls, ContNorm, 2/29, 7%, P < 0.0001). Twenty EldCa (53%) and 12 EldNorm (35%) used both exons 1c and 1d; however, their dominance was reversed (EldCa, all 1d > 1c; EldNorm, all 1c > 1d). CONCLUSIONS: Elderly breast tissues exhibited specific patterns in use of multiple exons 1, which at least partly explained the higher aromatase levels in EldCa. The mechanisms of how these specific patterns occur during aging and carcinogenesis should be further examined.

Lack of association of ovariectomy-induced obesity with overeating and the reduction of physical activities.

Obesity commonly occurs in postmenopausal women, increasing the risk of various diseases. Estrogen can prevent obesity by activating lipid metabolism and suppressing depressive behavior. However, the reasons for obesity in postmenopausal women are not clearly elucidated. To mimic the effect of estrogen decline in postmenopausal women, we analyzed the behavior and the lipid metabolism-related genes, PPARγ and CD36 in ovariectomized (OVX) mice. The OVX mice showed increased visceral fat mass and PPARγ and CD36 expression in the visceral fat. In contrast, they were not significantly affected in terms of physical activity and food intake. Further, subcutaneous supplementation of estrogen effectively suppressed the increase in subcutaneous and visceral fat mass in OVX mice. We conclude that obesity in postmenopausal women is unlikely to be caused by overeating and reduction in physical activity, and subcutaneous supplementation of estrogen is an effective strategy to prevent obesity in postmenopausal women.

Clinical Significance of Neoadjuvant Chemotherapy With Gemcitabine Plus S-1 for Resectable Pancreatic Ductal Adenocarcinoma.

BACKGROUND/AIM: Little is known about the efficacy of neoadjuvant chemotherapy (NAC) with gemcitabine plus S-1 (GS) for patients with resectable pancreatic ductal adenocarcinoma (R-PDAC). The aim of this study was to investigate differences in the long-term outcome of patients with R-PDAC undergoing pancreatectomy with and without NAC-GS to clarify the clinical significance of NAC-GS. PATIENTS AND METHODS: A total of 77 patients with R-PDAC who were scheduled for pancreatectomy between January 2012 and December 2017 were enrolled. Of these patients, 39 received NAC-GS (GS group) and 38 had upfront surgery (UFS group). RESULTS: Among the 77 patients, one patient in each group did not undergo pancreatectomy due to intraoperative non-curative factors. Median tumor size and the number of lymph nodes with metastasis were significantly lower in the GS group than in the UFS group (p=0.002 and p=0.017). However, the 5-year overall survival rate was similar in the two groups (26.1% versus 21.5%, p=0.930). CONCLUSION: NAC-GS may not be recommended for patients with R-PDAC since it does not seem to offer any survival benefits.

Mode of action and functional significance of estrogen-inducing dendritic growth, spinogenesis, and synaptogenesis in the developing Purkinje cell.

Neurosteroids are synthesized de novo from cholesterol in the brain. To understand neurosteroid action in the brain, data on the regio- and temporal-specific synthesis of neurosteroids are needed. Recently, we identified the Purkinje cell as an active neurosteroidogenic cell. In rodents, this neuron actively produces several neurosteroids including estradiol during neonatal life, when cerebellar neuronal circuit formation occurs. Estradiol may be involved in cerebellar neuronal circuit formation through promoting neuronal growth and neuronal synaptic contact, because the Purkinje cell expresses estrogen receptor-beta (ERbeta). To test this hypothesis, in this study we examined the effects of estradiol on dendritic growth, spinogenesis, and synaptogenesis in the Purkinje cell using neonatal wild-type (WT) mice or cytochrome P450 aromatase knock-out (ArKO) mice. Administration of estradiol to neonatal WT or ArKO mice increased dendritic growth, spinogenesis, and synaptogenesis in the Purkinje cell. In contrast, WT mice treated with tamoxifen, an ER antagonist, or ArKO mice exhibited decreased Purkinje dendritic growth, spinogenesis, and synaptogenesis at the same neonatal period. To elucidate the mode of action of estradiol, we further examined the expression of brain-derived neurotrophic factor (BDNF) in response to estrogen actions in the neonate. Estrogen administration to neonatal WT or ArKO mice increased the BDNF level in the cerebellum, whereas tamoxifen decreased the BDNF level in WT mice similar to ArKO mice. BDNF administration to tamoxifen-treated WT mice increased Purkinje dendritic growth. These results indicate that estradiol induces dendritic growth, spinogenesis, and synaptogenesis in the developing Purkinje cell via BDNF action during neonatal life.

Acute effects of oestrogen on the guinea pig and human IKr channels and drug-induced prolongation of cardiac repolarization.

Female gender is a risk factor for drug-induced arrhythmias associated with QT prolongation, which results mostly from blockade of the human ether-a-go-go-related gene (hERG) channel. Some clinical evidence suggests that oestrogen is a determinant of the gender-differences in drug-induced QT prolongation and baseline QT(C) intervals. Although the chronic effects of oestrogen have been studied, it remains unclear whether the gender differences are due entirely to transcriptional regulations through oestrogen receptors. We therefore investigated acute effects of the most bioactive oestrogen, 17beta-oestradiol (E2) at its physiological concentrations on cardiac repolarization and drug-sensitivity of the hERG (I(Kr)) channel in Langendorff-perfused guinea pig hearts, patch-clamped guinea pig cardiomyocytes and culture cells over-expressing hERG. We found that physiological concentrations of E2 partially suppressed I(Kr) in a receptor-independent manner. E2-induced modification of voltage-dependence causes partial suppression of hERG currents. Mutagenesis studies showed that a common drug-binding residue at the inner pore cavity was critical for the effects of E2 on the hERG channel. Furthermore, E2 enhanced both hERG suppression and QT(C) prolongation by its blocker, E4031. The lack of effects of testosterone at its physiological concentrations on both of hERG currents and E4031-sensitivity of the hERG channel implicates the critical role of aromatic centroid present in E2 but not in testosterone. Our data indicate that E2 acutely affects the hERG channel gating and the E4031-induced QT(C) prolongation, and may provide a novel mechanism for the higher susceptibility to drug-induced arrhythmia in women.

The characteristics of aromatase deficient hairless mice indicate important roles of extragonadal estrogen in the skin.

The roles of extragonadal estrogen in the skin are poorly understood, due to the lack of proper animal models. We examined the skin phenotypes of aromatase-knockout hairless (ArKO) mice and wild-type hairless (WT) mice, both of which were obtained through crossbreeding of Ar+/- mice and hairless mice. Differences in the skins of ArKO and WT mice were compared with those of ovariectomized (OVX) and control (Sham) mice. A difference was observed in the skin tone of ArKO mice, which is pale white and differs from the pinkish tone of all other mice. However, both ArKO and OVX mice similarly exhibited deteriorations of skin properties as compared to their respective controls. Furthermore, all the deteriorations were similarly amplified by chronic UVB irradiation in both ArKO and OVX mice as compared to their respective controls. The unique skin phenotype of ArKO mice was observed in sunburn reactions. Specifically, skins of ArKO mice showed no reaction after an acute UVB irradiation at dose intensities caused sunburn in others. However, follow-up observation found delayed reactions associated with brownish skin color and swelling only in ArKO mice, thereby suggesting that the role of extragonadal estrogen may be connected with the protective reactions of skin.