Progress in the molecular understanding of central regulation of body weight by estrogens

Neuroactive steroids in the neuroendocrine control of food intake, metabolism, and reproduction

Neuroactive steroids are a type of steroid hormones produced within the nervous system or in peripheral glands and then transported to the brain to exert their neuromodulatory effects. Neuroactive steroids have pleiotropic effects, that include promoting myelination, neuroplasticity, and brain development. They also regulate important physiological functions, such as metabolism, feeding, reproduction, and stress response. The homoeostatic processes of metabolism and reproduction are closely linked and mutually dependent. Reproductive events, such as pregnancy, bring about significant changes in metabolism, and metabolic status may affect reproductive function in mammals. In females, the regulation of reproduction and energy balance is controlled by the fluctuations of oestradiol and progesterone throughout the menstrual cycle. Neurosteroids play a key role in the neuroendocrine control of reproduction. The synthesis of neuroestradiol and neuroprogesterone within the brain is a crucial process that facilitates the release of GnRH and LH, which in turn, regulate the transition from oestrogen-negative to oestrogen-positive feedback. In addition to their function in the reproductive system, oestrogen has a key role in the regulation of energy homoeostasis by acting at central and peripheral levels. The oestrogenic effects on body weight homoeostasis are primarily mediated by oestrogen receptors-α (ERα), which are abundantly expressed in multiple brain regions that are implicated in the regulation of food intake, basal metabolism, thermogenesis, and brown tissue distribution. The tight interplay between energy balance and reproductive physiology is facilitated by shared regulatory pathways, namely POMC, NPY and kisspeptin neurons, which are targets of oestrogen regulation and likely participate in different aspects of the joint control of energy balance and reproductive function. The aim of this review is to present a summary of the progress made in uncovering shared regulatory pathways that facilitate the tight coupling between energy balance and reproductive physiology, as well as their reciprocal interactions and the modulation induced by neurosteroids.

Estrogen signaling in the dorsal raphe regulates binge-like drinking in mice

Estrogens promote binge alcohol drinking and contribute to sex differences in alcohol use disorder. However, the mechanisms are largely unknown. This study aims to test if estrogens act on 5-hydroxytryptamine neurons in the dorsal raphe nucleus (5-HTDRN) to promote binge drinking. We found that female mice drank more alcohol than male mice in chronic drinking in the dark (DID) tests. This sex difference was associated with distinct alterations in mRNA expression of estrogen receptor α (ERα) and 5-HT-related genes in the DRN, suggesting a potential role of estrogen/ERs/5-HT signaling. In supporting this view, 5-HTDRN neurons from naïve male mice had lower baseline firing activity but higher sensitivity to alcohol-induced excitation compared to 5-HTDRN neurons from naïve female mice. Notably, this higher sensitivity was blunted by 17β-estradiol treatment in males, indicating an estrogen-dependent mechanism. We further showed that both ERα and ERβ are expressed in 5-HTDRN neurons, whereas ERα agonist depolarizes and ERβ agonist hyperpolarizes 5-HTDRN neurons. Notably, both treatments blocked the stimulatory effects of alcohol on 5-HTDRN neurons in males, even though they have antagonistic effects on the activity dynamics. These results suggest that ERs' inhibitory effects on ethanol-induced burst firing of 5-HTDRN neurons may contribute to higher levels of binge drinking in females. Consistently, chemogenetic activation of ERα- or ERβ-expressing neurons in the DRN reduced binge alcohol drinking. These results support a model in which estrogens act on ERα/β to prevent alcohol-induced activation of 5-HTDRN neurons, which in return leads to higher binge alcohol drinking.

Network pharmacology and topological analysis on tibolone metabolites and their molecular mechanisms in traumatic brain injury

Traumatic brain injury (TBI) is a pathology of great social impact, affecting millions of people worldwide. Despite the scientific advances to improve the management of TBI in recent years, we still do not have a specific treatment that controls the inflammatory process after mechanical trauma. The discovery and implementation of new treatments is a long and expensive process, making the repurpose of approved drugs for other pathologies a clinical interest. Tibolone is a drug in use for the treatment of symptoms associated with menopause and has been shown to have a broad spectrum of actions by regulating estrogen, androgen and progesterone receptors, whose activation exerts potent anti-inflammatory and antioxidant effects. In the present study, we aimed to investigate the therapeutic potential of the tibolone metabolites 3α-Hydroxytibolone, 3β-Hydroxytibolone, and Δ4-Tibolone as a possible therapy in TBI using network pharmacology and network topology analysis. Our results demonstrate that the estrogenic component mediated by the α and β metabolites can regulate synaptic transmission and cell metabolism, while the Δ metabolite may be involved in modulating the post-TBI inflammatory process. We identified several molecular targets, including KDR, ESR2, AR, NR3C1, PPARD, and PPARA, which are known to play critical roles in the pathogenesis of TBI. Tibolone metabolites were predicted to regulate the expression of key genes involved in oxidative stress, inflammation, and apoptosis. Overall, the repurposing of tibolone as a neuroprotective treatment for TBI holds promise for future clinical trials. However, further studies are needed to confirm its efficacy and safety in TBI patients.

The role of oestrogen in determining sexual dimorphism in energy balance

Energy balance is determined by caloric intake and the rate at which energy is expended, with the latter comprising resting energy expenditure, physical activity and adaptive thermogenesis. The regulation of both energy intake and expenditure exhibits clear sexual dimorphism, with young women being relatively protected against weight gain and the development of cardiometabolic diseases. Preclinical studies have indicated that females are more sensitive to the satiety effects of leptin and insulin compared to males. Furthermore, females have greater thermogenic activity than males, whereas resting energy expenditure is generally higher in males than females. In addition to this, in post-menopausal women, the decline in sex steroid concentration, particularly in oestrogen, is associated with a shift in the distribution of adipose tissue and overall increased propensity to gain weight. Oestrogens are known to regulate energy balance and weight homeostasis via effects on both food intake and energy expenditure. Indeed, 17β-oestradiol treatment increases melanocortin signalling in the hypothalamus to cause satiety. Furthermore, oestrogenic action at the ventromedial hypothalamus has been linked with increased energy expenditure in female mice. We propose that oestrogen action on energy balance is multi-faceted and is fundamental to determining sexual dimorphism in weight control. Furthermore, evidence suggests that the decline in oestrogen levels leads to increased risk of weight gain and development of cardiometabolic disease in women across the menopausal transition.

Estrogen pollution of the European aquatic environment: A critical review

Among the plethora of chemicals released into the environment, much attention is paid to endocrine disrupting compounds (EDCs). Natural estrogens, such as estrone (E1), 17β-estradiol (E2), estriol (E3) are excreted by humans as well as animals, and can enter the environment as a result of discharging domestic sewage and animal waste. These compounds can cause deleterious effects such as feminization, infertility and hermaphroditism in organisms that inhabit water bodies. This study provides an overview of the level of estrogen exposures in surface waters, groundwater and river sediments in European countries. The conducted review shows that estrogen concentrations were within the range of 0.1 ng L - 10 ng /L in the majority of the tested environmental samples. However, the authors of the study point out that there are still many unexplored areas and a limited amount of data that mainly concerns Eastern European countries. The study also analysed the factors that influence the increased emissions of estrogens to the environment, which may be helpful for identifying particularly polluted areas.

The hypothalamus for whole-body physiology: from metabolism to aging

Obesity and aging are two important epidemic factors for metabolic syndrome and many other health issues, which contribute to devastating diseases such as cardiovascular diseases, stroke and cancers. The brain plays a central role in controlling metabolic physiology in that it integrates information from other metabolic organs, sends regulatory projections and orchestrates the whole-body function. Emerging studies suggest that brain dysfunction in sensing various internal cues or processing external cues may have profound effects on metabolic and other physiological functions. This review highlights brain dysfunction linked to genetic mutations, sex, brain inflammation, microbiota, stress as causes for whole-body pathophysiology, arguing brain dysfunction as a root cause for the epidemic of aging and obesity-related disorders. We also speculate key issues that need to be addressed on how to reveal relevant brain dysfunction that underlines the development of these disorders and diseases in order to develop new treatment strategies against these health problems.

Loss of the Protective Effect of Estrogen Contributes to Maternal Gestational Hypertension-Induced Hypertensive Response Sensitization Elicited by Postweaning High-Fat Diet in Female Offspring

Background

A recent study conducted in male offspring demonstrated that maternal gestational hypertension (MHT) induces hypertensive response sensitization (HTRS) elicited by postweaning high‐fat diet (HFD). In this study, we investigated the sensitizing effect of MHT on postweaning HFD‐induced hypertensive response in female rat offspring and assessed the protective role of estrogen in HTRS.

Methods and Results

The results showed that MHT also induced a sensitized HFD‐elicited hypertensive response in intact female offspring. However, compared with male offspring, this MHT‐induced HTRS was sex specific in that intact female offspring exhibited an attenuated increase in blood pressure. Ovariectomy significantly enhanced the HFD‐induced increase in blood pressure and the pressor response to centrally administered angiotensin II or tumor necrosis factor‐α in offspring of normotensive dams, which was accompanied by elevated centrally driven sympathetic activity, upregulated mRNA expression of prohypertensive components, and downregulated expression of antihypertensive components in the hypothalamic paraventricular nucleus. However, when compared with HFD‐fed ovariectomized offspring of normotensive dams, the MHT‐induced HTRS and pressor responses to centrally administered angiotensin II or tumor necrosis factor‐α in HFD‐fed intact offspring of MHT dams were not potentiated by ovariectomy, but the blood pressure and elicited pressor responses as well as central sympathetic tone remained higher.

Conclusions

The results indicate that in adult female offspring MHT induced HTRS elicited by HFD. Estrogen normally plays a protective role in antagonizing HFD prohypertensive effects, and MHT compromises this normal protective action of estrogen by augmenting brain reactivity and centrally driven sympathetic activity.

Hypothalamic Perineuronal Nets Are Regulated by Sex and Dietary Interventions

Perineuronal nets (PNNs) are widely present in the hypothalamus, and are thought to provide physical protection and ion buffering for neurons and regulate their synaptic plasticity and intracellular signaling. Recent evidence indicates that PNNs in the mediobasal hypothalamus play an important role in the regulation of glucose homeostasis. However, whether and how hypothalamic PNNs are regulated are not fully understood. In the present study, we examined whether PNNs in various hypothalamic regions in mice can be regulated by sex, gonadal hormones, dietary interventions, or their interactions. We demonstrated that gonadal hormones are required to maintain normal PNNs in the arcuate nucleus of hypothalamus in both male and female mice. In addition, PNNs in the terete hypothalamic nucleus display a sexual dimorphism with females higher than males, and high-fat diet feeding increases terete PNNs only in female mice but not in male mice. On the other hand, PNNs in other hypothalamic regions are not influenced by sex, gonadal hormones or dietary interventions. In summary, we demonstrated that hypothalamic PNNs are regulated in a region-specific manner and these results provide a framework to further investigate the potential functions of PNNs in regulating energy/glucose homeostasis at the interplay of sex, gonadal hormones and diets.

Impact of Estrogens Present in Environment on Health and Welfare of Animals

Simple Summary

Estrogens are a group of steroid hormones that recently have gained even more attention in the eyes of scientists. There is an ongoing discussion in the scientific community about their relevance as environmental contaminants and the danger they pose to animal health and welfare. In available literature we can find many examples of their negative effects and mechanisms that are involved with such phenomena.

Abstract

Nowadays, there is a growing interest in environmental pollution; however, knowledge about this aspect is growing at an insufficient pace. There are many potential sources of environmental contamination, including sex hormones—especially estrogens. The analyzed literature shows that estrone (E1), estradiol (E2), estriol (E3), and synthetic ethinyloestradiol (EE2) are the most significant in terms of environmental impact. Potential sources of contamination are, among others, livestock farms, slaughterhouses, and large urban agglomerations. Estrogens occurring in the environment can negatively affect the organisms, such as animals, through phenomena such as feminization, dysregulation of natural processes related to reproduction, lowering the physiological condition of the organisms, disturbances in the regulation of both proapoptotic and anti-apoptotic processes, and even the occurrence of neoplastic processes thus drastically decreasing animal welfare. Unfortunately, the amount of research conducted on the negative consequences of their impact on animal organisms is many times smaller than that of humans, despite the great richness and diversity of the fauna. Therefore, there is a need for further research to help fill the gaps in our knowledge.

Sex differences in insulin resistance, but not peripheral neuropathy, in a diet-induced prediabetes mouse model

Peripheral neuropathy (PN) is a common complication of prediabetes and diabetes and is an increasing problem worldwide. Existing PN treatments rely solely on glycemic control, which is effective in type 1 but not type 2 diabetes. Sex differences in response to anti-diabetic drugs further complicate the identification of effective PN therapies. Preclinical research has been primarily carried out in males, highlighting the need for increased sex consideration in PN models. We previously reported PN sex dimorphism in obese leptin-deficient ob/ob mice. This genetic model is inherently limited, however, owing to leptin's role in metabolism. Therefore, the current study goal was to examine PN and insulin resistance in male and female C57BL6/J mice fed a high-fat diet (HFD), an established murine model of human prediabetes lacking genetic mutations. HFD mice of both sexes underwent longitudinal phenotyping and exhibited expected metabolic and PN dysfunction compared to standard diet (SD)-fed animals. Hindpaw thermal latencies to heat were shorter in HFD females versus HFD males, as well as SD females versus males. Compared to HFD males, female HFD mice exhibited delayed insulin resistance, yet still developed the same trajectory of nerve conduction deficits and intraepidermal nerve fiber density loss. Subtle differences in adipokine levels were also noted by sex and obesity status. Collectively, our results indicate that although females retain early insulin sensitivity upon HFD challenge, this does not protect them from developing the same degree of PN as their male counterparts. This article has an associated First Person interview with the first author of the paper.

Mechanisms for Sex Differences in Energy Homeostasis

Sex differences exist in the regulation of energy homeostasis. Better understanding of the underlying mechanisms for sexual dimorphism in energy balance may facilitate development of gender-specific therapies for human diseases, e.g. obesity. Multiple organs, including the brain, liver, fat and muscle, play important roles in the regulations of feeding behavior, energy expenditure and physical activity, which therefore contribute to the maintenance of energy balance. It has been increasingly appreciated that this multi-organ system is under different regulations in male vs. female animals. Much of effort has been focused on roles of sex hormones (including androgens, estrogens and progesterone) and sex chromosomes in this sex-specific regulation of energy balance. Emerging evidence also indicates that other factors (not sex hormones/receptors and not encoded by the sex chromosomes) exist to regulate energy homeostasis differentially in males vs. females. In this review, we summarize factors and signals that have been shown to regulate energy homeostasis in a sexually dimorphic fashion and propose a framework where these factors and signals may be integrated to mediate sex differences in energy homeostasis.

Impact of estrogens and estrogen receptor-α in brain lipid metabolism

Estrogens and their receptors play key roles in regulating body weight, energy expenditure, and metabolic homeostasis. It is known that lack of estrogens promotes increased food intake and induces the expansion of adipose tissues, for which much is known. An area of estrogenic research that has received less attention is the role of estrogens and their receptors in influencing intermediary lipid metabolism in organs such as the brain. In this review, we highlight the actions of estrogens and their receptors in regulating their impact on modulating fatty acid content, utilization, and oxidation through their direct impact on intracellular signaling cascades within the central nervous system.

Central regulation of energy metabolism by estrogens

BACKGROUND

Estrogenic actions in the brain prevent obesity. Better understanding of the underlying mechanisms may facilitate development of new obesity therapies.

SCOPE OF REVIEW

This review focuses on the critical brain regions that mediate effects of estrogens on food intake and/or energy expenditure, the molecular signals that are involved, and the functional interactions between brain estrogens and other signals modulating metabolism. Body weight regulation by estrogens in male brains will also be discussed.

MAJOR CONCLUSIONS

17β-estradiol acts in the brain to regulate energy homeostasis in both sexes. It can inhibit feeding and stimulate brown adipose tissue thermogenesis. A better understanding of the central actions of 17β-estradiol on energy balance would provide new insight for the development of therapies against obesity in both sexes.

Emerging Roles of Estrogen-Related Receptors in the Brain: Potential Interactions with Estrogen Signaling

In addition to their well-known role in the female reproductive system, estrogens can act in the brain to regulate a wide range of behaviors and physiological functions in both sexes. Over the past few decades, genetically modified animal models have greatly increased our knowledge about the roles of estrogen receptor (ER) signaling in the brain in behavioral and physiological regulations. However, less attention has been paid to the estrogen-related receptors (ERRs), the members of orphan nuclear receptors whose sequences are homologous to ERs but lack estrogen-binding ability. While endogenous ligands of ERRs remain to be determined, they seemingly share transcriptional targets with ERs and their expression can be directly regulated by ERs through the estrogen-response element embedded within the regulatory region of the genes encoding ERRs. Despite the broad expression of ERRs in the brain, we have just begun to understand the fundamental roles they play at molecular, cellular, and circuit levels. Here, we review recent research advancement in understanding the roles of ERs and ERRs in the brain, with particular emphasis on ERRs, and discuss possible cross-talk between ERs and ERRs in behavioral and physiological regulations.

Sex Hormones and Cardiometabolic Health: Role of Estrogen and Estrogen Receptors

With increased life expectancy, women will spend over three decades of life postmenopause. The menopausal transition increases susceptibility to metabolic diseases such as obesity, diabetes, cardiovascular disease, and cancer. Thus, it is more important than ever to develop effective hormonal treatment strategies to protect aging women. Understanding the role of estrogens, and their biological actions mediated by estrogen receptors (ERs), in the regulation of cardiometabolic health is of paramount importance to discover novel targeted therapeutics. In this brief review, we provide a detailed overview of the literature, from basic science findings to human clinical trial evidence, supporting a protective role of estrogens and their receptors, specifically ERα, in maintenance of cardiometabolic health. In so doing, we provide a concise mechanistic discussion of some of the major tissue-specific roles of estrogens signaling through ERα. Taken together, evidence suggests that targeted, perhaps receptor-specific, hormonal therapies can and should be used to optimize the health of women as they transition through menopause, while reducing the undesired complications that have limited the efficacy and use of traditional hormone replacement interventions.

Brain nuclear receptors and body weight regulation

Neural pathways, especially those in the hypothalamus, integrate multiple nutritional, hormonal, and neural signals, resulting in the coordinated control of body weight balance and glucose homeostasis. Nuclear receptors (NRs) sense changing levels of nutrients and hormones, and therefore play essential roles in the regulation of energy homeostasis. Understanding the role and the underlying mechanisms of NRs in the context of energy balance control may facilitate the identification of novel targets to treat obesity. Notably, NRs are abundantly expressed in the brain, and emerging evidence indicates that a number of these brain NRs regulate multiple aspects of energy balance, including feeding, energy expenditure and physical activity. In this Review we summarize some of the recent literature regarding effects of brain NRs on body weight regulation and discuss mechanisms underlying these effects.

Weight gain in Turner Syndrome: association to puberty induction? - longitudinal analysis of KIGS data

CONTEXT

Girls with Turner Syndrome (TS) treated or not treated with growth hormone (GH) are prone to overweight. Therefore, we hypothesize that puberty induction in TS is associated with weight gain.

METHODS

We analyzed weight changes (BMI-SDS) between onset of GH treatment and near adult height (NAH) in 887 girls with TS enrolled in KIGS (Pfizer International Growth Database). Puberty was induced with estrogens in 646 (72·8%) girls with TS.

RESULTS

Weight status did not change significantly between GH treatment start and 1 year later (mean difference -0·02 BMI-SDS), but increased significantly (P < 0·001) until NAH (+0·40 BMI-SDS). The BMI-SDS increased +0·21 until start of puberty (P < 0·001). Girls with spontaneous and induced puberty showed similar BMI-SDS changes. Puberty induction at ≥12 years was associated with a significant (P < 0·001) less increase of BMI-SDS (+0·7 BMI-SDS) between baseline and NAH compared to puberty induction at <12 year (+1·0 BMI-SDS). In multiple linear regression analyses changes of BMI-SDS between baseline and NAH were negatively associated with baseline BMI-SDS (P < 0·001), GH doses (P = 0·015), and age at puberty induction (P < 0·001), positively with years on GH treatment (P = 0·004), while duration and dose of estrogens, its route of administration (transdermal/oral), changes of height-SDS, thyroxin and oxandrolone treatment, and karyotype did not correlate significantly to changes of BMI-SDS in this time period.

CONCLUSIONS

Puberty does not seem to play a major role in weight gain in girls with TS since the majority of the increases in BMI-SDS occurred before puberty. However, late puberty induction seems to decrease the risk of weight gain.

Sex differences in obesity development in pair-fed neuronal lipoprotein lipase deficient mice

Objective

Compared to men, postmenopausal women suffer from a disproportionate burden of many co-morbidities associated with obesity, e.g. cardiovascular disease, cancer, and dementia. The underlying mechanism for this sex difference is not well understood but is believed to relate to absence of the protective effect of estrogen through the action of estrogen receptor alpha (ERα) in the central nervous system. With the recently developed neuron-specific lipoprotein lipase deficient mice (NEXLPL−/−) (Wang et al., Cell Metabolism, 2011 [15]), we set to explore the possible role of lipid sensing in sex differences in obesity development.

Methods

Both male and female NEXLPL−/− mice and littermate WT controls were subjected to pair feeding (pf) where daily food amount given was adjusted according to body weight to match the food intake of ad libitum (ad) fed control WT mice. Food intake and body weight were measured daily, and pair feeding was maintained to 42 wk in male mice and to 38 wk in female mice. Various brain regions of the mice were harvested, and ERα gene expression was examined in both male and female NEXLPL−/− and WT control mice under both ad- and pf-fed conditions.

Results

Although both male and female NEXLPL−/− mice developed obesity similarly on standard chow, male NEXLPL−/− mice still developed obesity under with pair feeding, but on a much delayed time course, while female NEXLPL−/− mice were protected from extra body weight and fat mass gain compared to pair-fed WT control mice. Pair feeding alone induced extra fat mass gain in both male and female WT mice, and this was mostly driven by the reduction in physical activity. LPL deficiency resulted in an increase in ERα mRNA in the hypothalamus of ad-fed female mice, while pair feeding alone also resulted in an increase of ERα in both female WT control and NEXLPL−/− mice. The effect on increasing ERα by pair feeding and LPL deficiency was additive in pair-fed female NEXLPL−/− mice. ERα mRNA levels were not significantly modified in other brain regions examined, nor in the hypothalamus of male NEXLPL−/− mice compared to control mice.

Conclusions

These results suggest that the mechanism underlying ERα regulation of body weight interacts with the LPL-dependent lipid processing in the hypothalamus in a sex specific way. ERα could provide the link between brain lipid sensing and sex differences in obesity development. This study has the potential important clinical implication to provide better management for women who suffer from obesity and obesity-related co-morbidities.

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Male neuronal lipoprotein lipase deficient mice are still obese with pair feeding.

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Female neuronal lipoprotein lipase deficient mice are not obese with pair feeding.

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Neuronal LPL deficiency results in an increase in ERa expression in female mice.

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Pair feeding alone also results in an increase in ERa in both male and female mice.

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ERa provides the link between brain lipid sensing and sex differences in obesity.

Effects of chronic testosterone administration on body weight and food intake differ among pre-pubertal, gonadal-intact, and ovariectomized female rats

In females, estrogens play pivotal roles in preventing excessive body weight gain. On the other hand, the roles of androgen in female appetite and body weight regulation have not been fully studied. In this study, whether the roles of androgen in the regulation of body weight and appetite were different among ages and/or the estrogen milieu in females was evaluated. Body weight gain and food intake were increased by chronic testosterone administration in pre-pubertal and gonadal-intact female rats, but not in ovariectomized female rats. Testosterone administration also affected the serum leptin level and adipose leptin gene expression levels differently in each experimental condition. Hypothalamic mRNA levels of ERα, which plays pivotal roles in regulation of body weight and metabolism, were decreased by chronic testosterone administration in pre-pubertal and gonadal-intact female rats, but not in ovariectomized female rats. These results indicate that the effects of testosterone on body weight and appetite differed among ages and/or estrogen milieu in female rats, and that attenuation of estrogens' actions on the hypothalamus might be partly involved in the androgen-induced increases of body weight gain and food intake in females.

Visualizing estrogen receptor-α-expressing neurons using a new ERα-ZsGreen reporter mouse line

BACKGROUND

A variety of biological functions of estrogens, including regulation of energy metabolism, are mediated by neurons expressing estrogen receptor-α (ERα) in the brain. However, complex intracellular processes in these ERα-expressing neurons are difficult to unravel, due to the lack of strategy to visualize ERα-expressing neurons, especially in unfixed brain tissues.

RESULTS AND CONCLUSIONS

Here we generated a novel ERα-ZsGreen reporter mouse line in which expression of a green fluorescent reporter protein, ZsGreen, is driven by a 241kb ERα gene promoter. We validated that ZsGreen is highly colocalized with endogenous ERα in the brain. Native ZsGreen signals were visualized in unfixed brain tissue, and were used to assist single cell collection and electrophysiological recordings. Finally, we demonstrated that this ERα-ZsGreen mouse allele can be used in combination with other genetic reporter alleles to allow experiments in highly selective neural populations.

PI3K in the ventromedial hypothalamic nucleus mediates estrogenic actions on energy expenditure in female mice

Estrogens act in the ventromedial hypothalamic nucleus (VMH) to regulate body weight homeostasis. However, the molecular mechanisms underlying these estrogenic effects are unknown. We show that activation of estrogen receptor-α (ERα) stimulates neural firing of VMH neurons expressing ERα, and these effects are blocked with intracellular application of a pharmacological inhibitor of the phosphatidyl inositol 3-kinase (PI3K). Further, we demonstrated that mice with genetic inhibition of PI3K activity in VMH neurons showed a sexual dimorphic obese phenotype, with only female mutants being affected. In addition, inhibition of VMH PI3K activity blocked effects of 17β-estradiol to stimulate energy expenditure, but did not affect estrogen-induced anorexia. Collectively, our results indicate that PI3K activity in VMH neurons plays a physiologically relevant role in mediating estrogenic actions on energy expenditure in females.