Large-conductance Ca 2ϩ -activated K ϩ channels (BK, also called Maxi-K or Slo channels) are widespread in the vertebrate nervous system, but their functional roles in synaptic transmission in the mammalian brain are largely unknown. By combining electrophysiology and immunogold cytochemistry, we demonstrate the existence of functional BK channels in presynaptic terminals in the hippocampus and compare their functional roles in somata and terminals of CA3 pyramidal cells. Doublelabeling immunogold analysis with BK channel and glutamate receptor antibodies indicated that BK channels are targeted to the presynaptic membrane facing the synaptic cleft in terminals of Schaffer collaterals in stratum radiatum. Whole-cell, intracellular, and field-potential recordings from CA1 pyramidal cells showed that the presynaptic BK channels are activated by calcium influx and can contribute to repolarization of the presynaptic action potential (AP) and negative feedback control of Ca 2ϩ influx and transmitter release. This was observed in the presence of 4-aminopyridine (4-AP, 40-100 M), which broadened the presynaptic compound action potential. In contrast, the presynaptic BK channels did not contribute significantly to regulation of action potentials or transmitter release under basal experimental conditions, i.e., without 4-AP, even at high stimulation frequencies. This is unlike the situation in the parent cell bodies (CA3 pyramidal cells), where BK channels contribute strongly to action potential repolarization. These results indicate that the functional role of BK channels depends on their subcellular localization.

The present study investigates the regulation of small ubiquitin-related modifier-1 (SUMO-1) expression in response to hypoxia in adult mouse brain and heart. We observed a significant increase in SUMO-1 mRNAs and proteins after hypoxic stimulation in vivo. Because SUMO-1 interacts with various transcription factors, including hypoxia-inducible factor1b (HIF-1b) in vitro, we not only demonstrated that the HIF-1a expression is increased by hypoxia in brain and heart, but also provided evidence that SUMO-1 co-localizes in vivo with HIF1a in response to hypoxia by demonstrating the co-expression of these two proteins in neurons and cardiomyocytes. The specific interaction between SUMO-1 and HIF-1a was additionally demonstrated with co-immunoprecipitation. These results indicate that the increased levels of SUMO-1 participate in the modulation of HIF-1a function through sumoylation in brain and heart.

Women with polycystic ovary syndrome (PCOS) are at increased risk of miscarriage, which often accompanies the hyperandrogenism and insulin resistance seen in these patients. However, neither the combinatorial interaction between these two PCOS-related etiological factors nor the mechanisms of their actions in the uterus during pregnancy are well understood. We hypothesized that hyperandrogensim and insulin resistance exert a causative role in miscarriage by inducing defects in uterine function that are accompanied by mitochondrial-mediated oxidative stress, inflammation, and perturbed gene expression. Here, we tested this hypothesis by studying the metabolic, endocrine, and uterine abnormalities in pregnant rats after exposure to daily injection of 5α-dihydrotestosterone (DHT; 1.66 mg·kg body wt−1·day−1) and/or insulin (6.0 IU/day) from gestational day 7.5 to 13.5. We showed that whereas DHT-exposed and insulin-exposed pregnant rats presented impaired insulin sensitivity, DHT + insulin-exposed pregnant rats exhibited hyperandrogenism and peripheral insulin resistance, which mirrors pregnant PCOS patients. Compared with controls, hyperandrogenism and insulin resistance in the dam were associated with alterations in uterine morphology and aberrant expression of genes responsible for decidualization ( Prl8a2, Fxyd2, and Mt1g), placentation ( Fcgr3 and Tpbpa), angiogenesis ( Flt1, Angpt1, Angpt2, Ho1, Ccl2, Ccl5, Cxcl9, and Cxcl10) and insulin signaling (Akt, Gsk3, and Gluts). Moreover, we observed changes in uterine mitochondrial function and homeostasis (i.e., mitochondrial DNA copy number and the expression of genes responsible for mitochondrial fusion, fission, biogenesis, and mitophagy) and suppression of both oxidative and antioxidative defenses (i.e., reactive oxygen species, Nrf2 signaling, and interactive networks of antioxidative stress responses) in response to the hyperandrogenism and insulin resistance. These findings demonstrate that hyperandrogenism and insulin resistance induce mitochondria-mediated damage and a resulting imbalance between oxidative and antioxidative stress responses in the gravid uterus.

Polycystic ovary syndrome (PCOS) is a state of altered steroid hormone production and activity. Chronic estrogen exposure or lack of progesterone due to ovarian dysfunction can result in endometrial hyperplasia and carcinoma. A key contributor to our understanding of progesterone as a critical regulator for normal uterine function has been the elucidation of progesterone receptor (PR) expression, regulation, and signaling pathways. Several human studies indicate that PR-mediated signaling pathways in the nucleus are associated with progesterone resistance in women with PCOS. The aim of this review is to provide an overview of endometrial progesterone resistance in women with PCOS; to present the PR structure, its different isoforms, and their expression in the endometrium; to illustrate the possible regulation of PR and PR-mediated signaling in progesterone resistance in women with PCOS; and to discuss current clinical treatments for atypical endometrial hyperplasia and endometrial carcinoma in women with PCOS and accompanying progesterone resistance.

Glucagon-like peptide 1 (GLP-1), produced in the intestine and the brain, can stimulate insulin secretion from the pancreas and alleviate type 2 diabetes. The cytokine interleukin-6 (IL-6) may enhance insulin secretion from β-cells by stimulating peripheral GLP-1 production. GLP-1 and its analogs also reduce food intake and body weight, clinically beneficial actions that are likely exerted at the level of the CNS, but otherwise are poorly understood. The cytokines IL-6 and interleukin 1β (IL-1β) may exert an anti-obesity effect in the CNS during health. Here we found that central injection of a clinically used GLP-1 receptor agonist, exendin-4, potently increased the expression of IL-6 in the hypothalamus (11-fold) and the hindbrain (4-fold) and of IL-1β in the hypothalamus, without changing the expression of other inflammation-associated genes. Furthermore, hypothalamic and hindbrain interleukin-associated intracellular signals [phosphorylated signal transducer and activator of transcription-3 (pSTAT3) and suppressor of cytokine signaling-1 (SOCS1)] were also elevated by exendin-4. Pharmacologic disruption of CNS IL-1 receptor or IL-6 biological activity attenuated anorexia and body weight loss induced by central exendin-4 administration in a rat. Simultaneous blockade of IL-1 and IL-6 activity led to a more potent attenuation of exendin-4 effects on food intake. Mice with global IL-1 receptor gene knockout or central IL-6 receptor knockdown showed attenuated decrease in food intake and body weight in response to peripheral exendin-4 treatment. GLP-1 receptor activation in the mouse neuronal Neuro2A cell line also resulted in increased IL-6 expression. These data outline a previously unidentified role of the central IL-1 and IL-6 in mediating the anorexic and body weight loss effects of GLP-1 receptor activation.is an incretin hormone secreted from intestinal endocrine L-cells and also from pancreatic α-cells. Its ability to stimulate insulin secretion and regulate blood glucose has been used as a treatment for type 2 diabetes. Importantly, GLP-1 and its long-lasting analogs reduce food intake and body weight (see ref. 1 for review). These effects have been regarded as of potential clinical relevance for successful treatment of obesity. There is limited knowledge regarding the mechanisms behind the anorexic effect of GLP-1, but it is likely exerted at the level of the CNS (2-4). Central GLP-1 receptors (GLP-1R) are distributed throughout the CNS energybalance-regulating areas, including the hypothalamus and hindbrain (5). GLP-1-producing neurons in the nucleus of the solitary tract are likely the main source of the endogenous ligand to the central GLP-1Rs (6, 7). Peripherally applied long-lasting analogs, due to their ability to cross the blood brain barrier (8, 9), can also engage the central GLP-1R populations, making these CNS receptors a relevant clinical target. Even though the contribution of the central GLP-1Rs to energy balance regulation is clear, the understanding of the neural pathways and mechanisms...

Adult rats treated concomitantly with insulin and human chorionic gonadotropin exhibit endocrine, metabolic, and reproductive abnormalities that are very similar to those observed in polycystic ovary syndrome (PCOS) patients. In this study, we used this rat model to assess the effects of metformin on PCOS-related uterine dysfunction. In addition to reducing androgen levels, improving insulin sensitivity, and correcting the reproductive cycle, metformin treatment induced morphological changes in the PCOS-like uterus. At the molecular and cellular levels, metformin normalized the androgen receptor-mediated transcriptional program and restored epithelial–stromal interactions. In contrast to glucose transport, uterine inflammatory gene expression was suppressed through the PI3K–Akt–NFκB network, but without affecting apoptosis. These effects appeared to be independent of AMPK subunit and autophagy-related protein regulation. We found that when metformin treatment partially restored implantation, several implantation-related genes were normalized in the PCOS-like rat uterus. These results improve our understanding of how metformin rescues the disruption of the implantation process due to the uterine defects that result from hyperandrogenism and insulin resistance. Our data provide insights into the molecular and functional clues that might help explain, at least in part, the potential therapeutic options of metformin in PCOS patients with uterine dysfunction.

The intracellular progesterone receptor (PR) in the mammalian ovary is a part of the physiological pathway that facilitates ovulation. Two PR isoforms (A and B) exist, with different molecular and biological functions. Previous studies have revealed that the cellular ratio of the PR isoforms is important for progesterone-responsive tissues and is under developmental control in different species. However, the relative expression of PR isoforms in the ovary is unknown. In this study we have demonstrated first that the expression of both PR isoforms in mouse granulosa cells was rapidly up-regulated by hCG treatment and dramatically down-regulated when the granulosa cells were undergoing luteinization. The relative level of protein expression of the A and B forms was 2:1 and the highest total PR protein expression was found after hCG stimulation. Second, we demonstrated that the expression of PR protein was specific to granulosa cells of periovulatory follicles and was absent in undifferentiated granulosa cells of growing follicles. It was not detected in other cell types (i.e., corpora lutea or any stage of follicles with features of apoptosis). Third, we demonstrated that treatment with the PR antagonist RU 486 in vivo resulted in down-regulation of both isoforms in parallel with increased activation of caspase-3, a decreased level of proliferating cell nuclear antigen, and a reduced rate of ovulation. Fourth, we demonstrated, in vitro, that the PR antagonists RU 486 and Org 31710 increased internucleosomal DNA fragmentation parallel with a decrease in DNA synthesis in granulosa cells, which express PR. These results indicate that PR and its isoforms participate in regulation of ovulation, along with suppression of granulosa cell apoptosis and promotion of cell survival in the mouse ovary.

-Victorin E. Maternal androgen excess reduces placental and fetal weights, increases placental steroidogenesis, and leads to long-term health effects in their female offspring. Am J Physiol Endocrinol Metab 303: E1373-E1385, 2012. First published October 9, 2012 doi:10.1152/ajpendo.00421.2012.-Here, we tested the hypothesis that excess maternal androgen in late pregnancy reduces placental and fetal growth, increases placental steroidogenesis, and adversely affects glucose and lipid metabolism in adult female offspring. Pregnant Wistar rats were randomly assigned to treatment with testosterone (daily injections of 5 mg of free testosterone from gestational days 16 to 19) or vehicle alone. In experiment 1, fetal and placental weights, circulating maternal testosterone, estradiol, and corticosterone levels, and placental protein expression and distribution of estrogen receptor-␣ and -␤, androgen receptor, and 17␤-hydroxysteroid dehydrogenase 2 were determined. In experiment 2, birth weights, postnatal growth rates, circulating testosterone, estradiol, and corticosterone levels, insulin sensitivity, adipocyte size, lipid profiles, and the presence of nonalcoholic fatty liver were assessed in female adult offspring. Treatment with testosterone reduced placental and fetal weights and increased placental expression of all four proteins. The offspring of testosterone-treated dams were born with intrauterine growth restriction; however, at 6 wk of age there was no difference in body weight between the offspring of testosterone-and control-treated rats. At 10 -11 wk of age, the offspring of the testosterone-treated dams had less fat mass and smaller adipocyte size than those born to control rats and had no difference in insulin sensitivity. Circulating triglyceride levels were higher in the offspring of testosterone-treated dams, and they developed nonalcoholic fatty liver as adults. We demonstrate for the first time that prenatal testosterone exposure alters placental steroidogenesis and leads to dysregulation of lipid metabolism in their adult female offspring. testosterone; prenatal; maternal; placenta; polycystic ovary syndrome; insulin sensitivity; steroidogenesis; estrogen receptor; androgen receptor THE MATERNAL ENVIRONMENT may influence epigenetic processes during placental and fetal development that have long-lasting effects and lead to diseases such as hypertension, obesity, type 2 diabetes, and endocrine and reproductive dysfunction in adult offspring (6,24). Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age and is associated with hyperandrogenism, oligo/anovulation (infertility), and polycystic ovaries (5, 26). PCOS is also associated with metabolic disturbances such as hyperinsulinemia and type 2 diabetes and dysfunctional lipid profile, symptoms that are aggravated by obesity (5). Women with PCOS are at a higher risk of delivering prematurely, developing gestational diabetes and preeclampsia (33), and having both small-for-gestational-age (40) and large-for-...