Estradiol regulates corticotropin-releasing hormone gene (crh) expression in a rapid and phasic manner that parallels estrogen receptor-alpha and -beta recruitment to a 3',5'-cyclic adenosine 5'-monophosphate regulatory region of the proximal crh promoter

Neuroendocrine contribution to sex-related variations in adverse air pollution health effects

Air pollution exposure is ranked as a leading environmental risk factor for not only cardiopulmonary diseases but also for systemic health ailments including diabetes, reproductive abnormalities, and neuropsychiatric disorders, likely mediated by central neural stress mechanisms. Current experimental evidence links many air pollution health outcomes with activation of neuroendocrine sympathetic-adrenal-medullary and hypothalamic-pituitary-adrenal (HPA) stress axes associated with resultant increases in adrenal-derived hormone levels acting as circulating mediators of multi-organ stress reactions. Epidemiological and experimental investigations also demonstrated sex-specific responses to air pollutant inhalation, which may be attributed to hormonal interactions within the stress and reproductive axes. Sex hormones (androgens and estrogens) interact with neuroendocrine functions to influence hypothalamic responses, subsequently augmenting stress-mediated metabolic and immune changes. These neurohormonal interactions may contribute to innate sex-specific responses to inhaled irritants, inducing differing individual susceptibility. The aim of this review was to: (1) examine neuroendocrine co-regulation of the HPA axis by gonadal hormones, (2) provide experimental evidence demonstrating sex-specific respiratory and systemic effects attributed to air pollutant inhalation exposure, and (3) postulate proposed mechanisms of stress and sex hormone interactions during air pollution-related stress.

Chronic stress and its effects on behavior, RNA expression of the bed nucleus of the stria terminalis, and the M-current of NPY neurons

Mood disorders, like major depressive disorder, can be precipitated by chronic stress and are more likely to be diagnosed in cisgender women than in cisgender men. This suggests that stress signaling in the brain is sexually dimorphic. We used a chronic variable mild stress paradigm to stress female and male mice for 6 weeks, followed by an assessment of avoidance behavior: the open field test, the elevated plus maze, the light/dark box emergence test, and the novelty suppressed feeding test. Additional cohorts were used for bulk RNA-Sequencing of the anterodorsal bed nucleus of the stria terminalis (adBNST) and whole-cell patch clamp electrophysiology in NPY-expressing neurons of the adBNST to record stress-sensitive M-currents. Our results indicate that females are more affected by chronic stress as indicated by an increase in avoidance behaviors, but that this is also dependent on the estrous stage of the animals such that diestrus females show more avoidant behaviors regardless of stress treatment. Results also indicate that NPY-expressing neurons of the adBNST are not major mediators of chronic stress as the M-current was not affected by treatment. RNA-Sequencing data suggests sex differences in estrogen signaling, serotonin signaling, and orexin signaling in the adBNST. Our results indicate that chronic stress influences behavior in a sex- and estrous stage-dependent manner but NPY-expressing neurons in the BNST are not the mediators of these effects.

Epigenetic mechanisms underlying stress-induced visceral pain: Resilience versus vulnerability in a two-hit model of early life stress and chronic adult stress

BACKGROUND

Women with a history of early life stress (ELS) have a higher risk of developing irritable bowel syndrome (IBS). In addition, chronic stress in adulthood can exacerbate IBS symptoms such as abdominal pain due to visceral hypersensitivity. We previously showed that sex and the predictability of ELS determine whether rats develop visceral hypersensitivity in adulthood. In female rats, unpredictable ELS confers vulnerability and results in visceral hypersensitivity, whereas predictable ELS induces resilience and does not induce visceral hypersensitivity in adulthood. However, this resilience is lost after exposure to chronic stress in adulthood leading to an exacerbation of visceral hypersensitivity. Evidence suggests that changes in histone acetylation at the promoter regions of glucocorticoid receptor (GR) and corticotrophin-releasing factor (CRF) in the central nucleus of the amygdala (CeA) underlie stress-induced visceral hypersensitivity. Here, we aimed to investigate the role of histone acetylation in the CeA on visceral hypersensitivity in a two-hit model of ELS followed by chronic stress in adulthood.

METHODS

Male and female neonatal rats were exposed to unpredictable, predictable ELS, or odor only (no stress control) from postnatal days 8 to 12. In adulthood, rats underwent stereotaxic implantation of indwelling cannulas. Rats were exposed to chronic water avoidance stress (WAS, 1 h/day for 7 days) or SHAM stress and received infusions of vehicle, the histone deacetylase inhibitor trichostatin A (TSA) or the histone acetyltransferase inhibitor garcinol (GAR) after each WAS session. 24 h after the final infusion, visceral sensitivity was assessed and the CeA was removed for molecular experiments.

RESULTS

In the two-hit model (ELS + WAS), female rats previously exposed to predictable ELS, showed a significant reduction in histone 3 lysine 9 (H3K9) acetylation at the GR promoter and a significant increase in H3K9 acetylation at the CRF promoter. These epigenetic changes were associated with changes in GR and CRF mRNA expression in the CeA and an exacerbation of stress-induced visceral hypersensitivity in female animals. TSA infusions in the CeA attenuated the exacerbated stress-induced visceral hypersensitivity, whereas GAR infusions only partially ameliorated ELS+WAS induced visceral hypersensitivity.

CONCLUSION

The two-hit model of ELS followed by WAS in adulthood revealed that epigenetic dysregulation occurs after exposure to stress in two important periods of life and contributes to the development of visceral hypersensitivity. These aberrant underlying epigenetic changes may explain the exacerbation of stress-induced abdominal pain in IBS patients.

Unraveling corticotropin-releasing factor family-orchestrated signaling and function in both sexes

Stress responses to physical, psychological, environmental, or cellular stressors, has two arms: initiation and recovery. Corticotropin-releasing factor (CRF) is primarily responsible for regulating and/or initiating stress responses via, whereas urocortins (UCNs) are involved in the recovery response to stress via feedback inhibition. Stress is a loaded, polysemous word and is experienced in a myriad of ways. Some stressors are good for an individual, in fact essential, whereas other stressors are associated with bad outcomes. Perceived stress, like beauty, lies in the eye of the beholder, and hence the same stressor can result in individual-specific outcomes. In mammals, there are two main biological sexes with reproduction as primary function. Reproduction and nutrition can also be viewed as stressors; based on a body of work from my laboratory, we propose that the functions of all other organs have co-evolved to optimize and facilitate an individual's nutritional and reproductive functions. Hence, sex differences in physiologically relevant outcomes are innate and occur at all levels- molecular, endocrine, immune, and (patho)physiological. CRF and three UCNs are peptide hormones that mediate their physiological effects by binding to two known G protein-coupled receptors (GPCRs), CRF1 and CRF2. Expression and function of CRF family of hormones and their receptors is likely to be sexually dimorphic in all organs. In this chapter, based on the large body of work from others and my laboratory, an overview of the CRF family with special emphasis on sex-specific actions of peripherally expressed CRF2 receptor in health and disease is provided.

Preterm Birth and Corticotrophin-Releasing Hormone as a Placental Clock

Preterm birth worldwide remains a significant cause of neonatal morbidity and mortality, yet the exact mechanisms of preterm parturition remain unclear. Preterm birth is not a single condition, but rather a syndrome with a multifactorial etiology. This multifactorial nature explains why individual predictive measures for preterm birth have had limited sensitivity and specificity. One proposed pathway for preterm birth is via placentally synthesized corticotrophin-releasing hormone (CRH). CRH is a peptide hormone that increases exponentially in pregnancy and has been implicated in preterm birth because of its endocrine, autocrine, and paracrine roles. CRH has actions that increase placental production of estriol and of the transcription factor nuclear factor-κB, that likely play a key role in activating the myometrium. CRH has been proposed as part of a placental clock, with early activation of placental production resulting in preterm birth. This article will review the current understanding of preterm birth, CRH as an initiator of human parturition, and the evidence regarding the use of CRH in the prediction of preterm birth.

Review of Herbal Medicines for the Treatment of Depression

Depression, a mental illness that is receiving increasing attention, is caused by multiple factors and genes and adversely affects social life and health. Several hypotheses have been proposed to clarify the pathogenesis of depression, and various synthetic antidepressants have been introduced to treat patients with depression. However, these drugs are effective only in a proportion of patients and fail to achieve complete remission. Recently, herbal medicines have received much attention as alternative treatments for depression because of their fewer side effects and lower costs. In this review, we have mainly focused on the herbal medicines that have been proven in clinical studies (especially randomized controlled trials and preclinical studies) to have antidepressant effects; we also describe the potential mechanisms of the antidepressant effects of those herbal medicines; the cellular and animal model of depression; and the development of novel drug delivery systems for herbal antidepressants. Finally, we objectively elaborate on the challenges of using herbal medicines as antidepressants and describe the benefits, adverse effects, and toxicity of these medicines.

Sex-dependent effects of multiple acute concurrent stresses on memory: a role for hippocampal estrogens

Memory disruption commonly follows chronic stress, whereas acute stressors are generally benign. However, acute traumas such as mass shootings or natural disasters—lasting minutes to hours and consisting of simultaneous physical, social, and emotional stresses—are increasingly recognized as significant risk factors for memory problems and PTSD. Our prior work has revealed that these complex stresses (concurrent multiple acute stresses: MAS) disrupt hippocampus-dependent memory in male rodents. In females, the impacts of MAS are estrous cycle-dependent: MAS impairs memory during early proestrus (high estrogens phase), whereas the memory of female mice stressed during estrus (low estrogens phase) is protected. Female memory impairments limited to high estrogens phases suggest that higher levels of estrogens are necessary for MAS to disrupt memory, supported by evidence that males have higher hippocampal estradiol than estrous females. To test the role of estrogens in stress-induced memory deficits, we blocked estrogen production using aromatase inhibitors. A week of blockade protected male and female mice from MAS-induced memory disturbances, suggesting that high levels of estrogens are required for stress-provoked memory impairments in both males and females. To directly quantify 17β-estradiol in murine hippocampus we employed both ELISA and mass spectrometry and identified significant confounders in both procedures. Taken together, the cross-cycle and aromatase studies in males and females support the role for high hippocampal estrogens in mediating the effect of complex acute stress on memory. Future studies focus on the receptors involved, the longevity of these effects, and their relation to PTSD-like behaviors in experimental models.

On the Interplay Between the Medicine of Hildegard of Bingen and Modern Medicine: The Role of Estrogen Receptor as an Example of Biodynamic Interface for Studying the Chronic Disease's Complexity

Introduction

Hildegard of Bingen (1098-1179) interpreted the origins of chronic disease highlighting and anticipating, although only in a limited fashion, the importance that complex interactions among numerous genetic, internal milieu and external environmental factors have in determining the disease phenotype. Today, we recognize those factors, capable of mediating the transmission of messages between human body and environment and vice versa, as biodynamic interfaces.

Aim

We analyzed, in the light of modern scientific evidence, Hildegard of Bingen's medical approach and her original humoral theory in order to identify possible insights included in her medicine that could be referred to in the context of modern evidence-based medicine. In particular, the abbess's humoral theory suggests the identification of biodynamic interfaces with sex hormones and their receptors.

Findings

We found that the Hildegardian holistic vision of the organism-environment relationship can actually represent a visionary approach to modern endocrinology and that sex hormones, in particular estrogens, could represent an example of a biodynamic interface. Estrogen receptors are found in regions of the brain involved in emotional and cognitive regulation, controlling the molecular mechanism of brain function. Estrogen receptors are involved in the regulation of the hypothalamic-pituitary-adrenal axis and in the epigenetic regulation of responses to physiological, social, and hormonal stimuli. Furthermore, estrogen affects gene methylation on its own and related receptor promoters in discrete regions of the developing brain. This scenario was strikingly perceived by the abbess in the XIIth century, and depicted as a complex interplay among different humors and flegmata that she recognized to be sex specific and environmentally regulated.

Viewpoint

Considering the function played by hormones, analyzed through the last scientific evidence, and scientific literature on biodynamic interfaces, we could suggest Hildegardian insights and theories as the first attempt to describe the modern holistic, sex-based medicine.

Conclusion

Hildegard anticipated a concept of pathogenesis that sees a central role for endocrinology in sex-specific disease. Furthermore, estrogens and estrogen receptors could represent a good example of molecular interfaces capable of modulating the interaction between the organism internal milieu and the environmental factors.

The hypothalamic paraventricular nucleus as a central hub for the estrogenic modulation of neuroendocrine function and behavior

Estradiol and hypothalamic paraventricular nucleus (PVN) help coordinate reproduction with body physiology, growth and metabolism. PVN integrates hormonal and neural signals originating in the periphery, generating an output mediated both by its long-distance neuronal projections, and by a variety of neurohormones produced by its magnocellular and parvocellular neurosecretory cells. Here we review the cyto-and chemo-architecture, the connectivity and function of PVN and the sex-specific regulation exerted by estradiol on PVN neurons and on the expression of neurotransmitters, neuromodulators, neuropeptides and neurohormones in PVN. Classical and non-classical estrogen receptors (ERs) are expressed in neuronal afferents to PVN and in specific PVN interneurons, projecting neurons, neurosecretory neurons and glial cells that are involved in the input-output integration and coordination of neurohormonal signals. Indeed, PVN ERs are known to modulate body homeostatic processes such as autonomic functions, stress response, reproduction, and metabolic control. Finally, the functional implications of the estrogenic modulation of the PVN for body homeostasis are discussed.

Sex-Related Predisposition to Post-Traumatic Stress Disorder Development-The Role of Neuropeptides

Post-traumatic stress disorder (PTSD) is characterized by re-experiencing a traumatic event, avoidance, negative alterations in cognitions and mood, hyperarousal, and severe functional impairment. Women have a two times higher risk of developing PTSD than men. The neurobiological basis for the sex-specific predisposition to PTSD might be related to differences in the functions of stress-responsive systems due to the interaction between gonadal hormones and stress peptides such as corticotropin-releasing factor (CRF), orexin, oxytocin, and neuropeptide Y. Additionally, in phases where estrogens levels are low, the risk of developing or exacerbating PTSD is higher. Most studies have revealed several essential sex differences in CRF function. They include genetic factors, e.g., the CRF promoter contains estrogen response elements. Importantly, sex-related differences are responsible for different predispositions to PTSD and diverse treatment responses. Fear extinction (the process responsible for the effectiveness of behavioral therapy for PTSD) in women during periods of high endogenous estradiol levels (the primary form of estrogens) is reportedly more effective than in periods of low endogenous estradiol. In this review, we present the roles of selected neuropeptides in the sex-related predisposition to PTSD development.

Stress-induced visceral pain in female rats is associated with epigenetic remodeling in the central nucleus of the amygdala

Stress and anxiety contribute to the pathophysiology of irritable bowel syndrome (IBS), a female-predominant disorder of the gut-brain axis, characterized by abdominal pain due to heightened visceral sensitivity. In the current study, we aimed to evaluate in female rats whether epigenetic remodeling in the limbic brain, specifically in the central nucleus of the amygdala (CeA), is a contributing factor in stress-induced visceral hypersensitivity. Our results showed that 1 h exposure to water avoidance stress (WAS) for 7 consecutive days decreased histone acetylation at the GR promoter and increased histone acetylation at the CRH promoter in the CeA. Changes in histone acetylation were mediated by the histone deacetylase (HDAC) SIRT-6 and the histone acetyltransferase CBP, respectively. Administration of the HDAC inhibitor trichostatin A (TSA) into the CeA prevented stress-induced visceral hypersensitivity through blockade of SIRT-6 mediated histone acetylation at the GR promoter. In addition, HDAC inhibition within the CeA prevented stress-induced histone acetylation of the CRH promoter. Our results suggest that, in females, epigenetic modifications in the limbic brain regulating GR and CRH expression contribute to stress-induced visceral hypersensitivity and offer a potential explanation of how stress can trigger symptoms in IBS patients.

Steroid receptor coactivator-1: The central intermediator linking multiple signals and functions in the brain and spinal cord

The effects of steroid hormones are believed to be mediated by their nuclear receptors (NRs). The p160 coactivator family, including steroid receptor coactivator-1 (SRC-1), 2 and 3, has been shown to physically interact with NRs to enhance their transactivational activities. Among which SRC-1 has been predominantly localized in the central nervous system including brain and spinal cord. It is not only localized in neurons but also detectable in neuroglial cells (mainly localized in the nuclei but also detectable in the extra-nuclear components). Although the expression of SRC-1 is regulated by many steroids, it is also regulated by some non-steroidal factors such as injury, sound and light. Functionally, SRC-1 has been implied in normal function such as development and ageing, learning and memory, central regulation on reproductive behaviors, motor and food intake. Pathologically, SRC-1 may play a role in the regulation of neuropsychiatric disorders (including stress, depression, anxiety, and autism spectrum disorder), metabolite homeostasis and obesity as well as tumorigenesis. Under most conditions, the related mechanisms are far from elucidation; although it may regulate spatial memory through Rictor/mTORC2-actin polymerization related synaptic plasticity. Several inhibitors and stimulator of SRC-1 have shown anti-cancer potentials, but whether these small molecules could be used to modulate ageing and central disorder related neuropathology remain unclear. Therefore, to elucidate when and how SRC-1 is turned on and off under different stimuli is very interesting and great challenge for neuroscientists.

(3α,5α)3-hydroxypregnan-20-one (3α,5α-THP) regulation of hypothalamic and extrahypothalamic corticotropin releasing factor (CRF): Sexual dimorphism and brain region specificity in Sprague Dawley rats

CRF is the main activator of the hypothalamic-pituitary-adrenal (HPA) axis in response to stress. CRF neurons are found mainly in the hypothalamus, but CRF positive cells and CRF1 receptors are also found in extrahypothalamic structures, including amygdala (CeA), hippocampus, NAc and VTA. CRF release in the hypothalamus is regulated by inhibitory GABAergic interneurons and extrahypothalamic glutamatergic inputs, and disruption of this balance is found in stress-related disorders and addiction. (3α,5α)3-hydroxypregnan-20-one (3α,5α-THP), the most potent positive modulator of GABA_A receptors, attenuates the stress response reducing hypothalamic CRF mRNA expression and ACTH and corticosterone serum levels. In this study, we explored 3α,5α-THP regulation of hypothalamic and extrahypothalamic CRF mRNA and peptide expression, in male and female Sprague Dawley rats, following vehicle or 3α,5α-THP administration (15 mg/kg). In the hypothalamus, we found sex differences in CRF mRNA expression (females +74%, p < 0.01) and CRF peptide levels (females -71%, p < 0.001). 3α,5α-THP administration reduced hypothalamic CRF mRNA expression only in males (-50%, p < 0.05) and did not alter CRF peptide expression in either sex. In hippocampus and CeA, 3α,5α-THP administration reduced CRF peptide concentrations only in the male (hippocampus -29%, p < 0.05; CeA -62%, p < 0.01). In contrast, 3α,5α-THP injection increased CRF peptide concentration in the VTA of both males (+32%, p < 0.01) and females (+26%, p < 0.01). The results show sex and region-specific regulation of CRF signals and the response to 3α,5α-THP administration. This data may be key to successful development of therapeutic approaches for stress-related disorders and addiction.

Biological intersection of sex, age, and environment in the corticotropin releasing factor (CRF) system and alcohol

The neuropeptide corticotropin-releasing factor (CRF) is critical in neural circuit function and behavior, particularly in the context of stress, anxiety, and addiction. Despite a wealth of preclinical evidence for the efficacy of CRF receptor 1 antagonists in reducing behavioral pathology associated with alcohol exposure, several clinical trials have had disappointing outcomes, possibly due to an underappreciation of the role of biological variables. Although he National Institutes of Health (NIH) now mandate the inclusion of sex as a biological variable in all clinical and preclinical research, the current state of knowledge in this area is based almost entirely on evidence from male subjects. Additionally, the influence of biological variables other than sex has received even less attention in the context of neuropeptide signaling. Age (particularly adolescent development) and housing conditions have been shown to affect CRF signaling and voluntary alcohol intake, and the interaction between these biological variables is particularly relevant to the role of the CRF system in the vulnerability or resilience to the development of alcohol use disorder (AUD). Going forward, it will be important to include careful consideration of biological variables in experimental design, reporting, and interpretation. As new research uncovers conditions in which sex, age, and environment play major roles in physiological and/or pathological processes, our understanding of the complex interaction between relevant biological variables and critical signaling pathways like the CRF system in the cellular and behavioral consequences of alcohol exposure will continue to expand ultimately improving the ability of preclinical research to translate to the clinic. This article is part of the special issue on Neuropeptides.

Multidimensional Top-Down Proteomics of Brain-Region-Specific Mouse Brain Proteoforms Responsive to Cocaine and Estradiol

Cocaine addiction afflicts nearly 1 million adults in the United States, and to date, there are no known treatments approved for this psychiatric condition. Women are particularly vulnerable to developing a cocaine use disorder and suffer from more serious cardiac consequences than men when using cocaine. Estrogen is one biological factor contributing to the increased risk for females to develop problematic cocaine use. Animal studies have demonstrated that estrogen (17β-estradiol or E2) enhances the rewarding properties of cocaine. Although E2 affects the dopamine system, the molecular and cellular mechanisms of E2-enhanced cocaine reward have not been characterized. In this study, quantitative top-down proteomics was used to measure intact proteins in specific regions of the female mouse brain after mice were trained for cocaine-conditioned place preference, a behavioral test of cocaine reward. Several proteoform changes occurred in the ventral tegmental area after combined cocaine and E2 treatments, with the most numerous proteoform alterations on myelin basic protein, indicating possible changes in white matter structure. There were also changes in histone H4, protein phosphatase inhibitors, cholecystokinin, and calmodulin proteoforms. These observations provide insight into estrogen signaling in the brain and may guide new approaches to treating women with cocaine use disorder.

Glucocorticoid-induced leucine zipper "quantifies" stressors and increases male susceptibility to PTSD

Post-traumatic stress disorder (PTSD) selectively develops in some individuals exposed to a traumatic event. Genetic and epigenetic changes in glucocorticoid pathway sensitivity may be essential for understanding individual susceptibility to PTSD. This study focuses on PTSD markers in the glucocorticoid pathway, spotlighting glucocorticoid-induced leucine zipper (GILZ), a transcription factor encoded by the gene Tsc22d3 on the X chromosome. We propose that GILZ uniquely "quantifies" exposure to stressors experienced from late gestation to adulthood and that low levels of GILZ predispose individuals to PTSD in males only. GILZ mRNA and methylation were measured in 396 male and female human blood samples from the Grady Trauma Project cohort (exposed to multiple traumatic events). In mice, changes in glucocorticoid pathway genes were assessed following exposure to stressors at distinct time points: (i) CRF-induced prenatal stress (_CRF-inducedPNS) with, or without, additional exposure to (ii) PTSD induction protocol in adulthood, which induces PTSD-like behaviors in a subset of mice. In humans, the number of traumatic events correlated negatively with GILZ mRNA levels and positively with % methylation of GILZ in males only. In male mice, we observed a threefold increase in the number of offspring exhibiting PTSD-like behaviors in those exposed to both _CRF-inducedPNS and PTSD induction. This susceptibility was associated with reduced GILZ mRNA levels and epigenetic changes, not found in females. Furthermore, virus-mediated shRNA knockdown of amygdalar GILZ increased susceptibility to PTSD. Mouse and human data confirm that dramatic alterations in GILZ occur in those exposed to a stressor in early life, adulthood or both. Therefore, GILZ levels may help identify at-risk populations for PTSD prior to additional traumatic exposures.

Reduced phosphodiesterase-2 activity in the amygdala results in anxiolytic-like effects on behavior in mice

BACKGROUND

Phosphodiesterase-2 (PDE2) is a cyclic nucleotide phosphodiesterase and is highly expressed in the amygdala, which suggests its important role in anxiety-like behavior.

AIMS

The present study examined whether reduced PDE2A expression in the central nucleus of the amygdala (CeA) produces anxiolytic-like effects in mice.

METHODS

PDE2A knockdown in amygdaloid (AR5) cells or the CeA was established using a lentiviral vector-based siRNA system. The anxiety-like behaviors were detected by the elevated plus maze (EPM) and hole-board tests in mice. The related proteins involved in cAMP/cGMP-dependent signaling, such as specific marker VASP^ser239, CREB^ser133 and BDNF were detected by immunoblot analysis.

RESULTS

PDE2A inhibition in AR-5 cells resulted in increases in cAMP/cGMP-related pVASP^ser239 and pCREB^ser133. Behavioral tests showed that PDE2A knockdown in the CeA induced anxiolytic-like effects as evidenced by the increases in percentages of open-arm entries and time spent in the open arms in the EPM test, and the increases in head dips and time spent in head dipping in the hole-board test. However, these anxiolytic-like effects were antagonized by pre-treatment of soluble guanylyl cyclase inhibitor ODQ or adenylate cyclase inhibitor SQ. Furthermore, PDE2A knockdown significantly increased pVASP^Ser239, pCREB^Ser133 and decreased BDNF expression in the amygdala. Pre-intra-CeA of ODQ or SQ reversed or partially prevented the effects of PDE2A knockdown on these proteins.

CONCLUSIONS

The results suggest that PDE2A plays a crucial role in the regulation of anxiety by the cGMP/cAMP-dependent pVASP-pCREB-BDNF signaling pathway.

Effect of oestrogen-dependent vasopressin on HPA axis in the median eminence of female rats

The median eminence (ME) anatomically consists of external (eME) and internal (iME) layers. The hypothalamic neurosecretory cells terminate their axons in the eME and secrete their neurohormones regulating anterior pituitary hormone secretion involved in stress responses into the portal vein located in the eME. Magnocellular neurosecretory cells (MNCs) which produce arginine vasopressin (AVP) and oxytocin in the paraventricular (PVN) and supraoptic nuclei (SON) terminate their axons in the posterior pituitary gland (PP) through the iME. Here, we provide the first evidence that oestrogen modulates the dynamic changes in AVP levels in the eME axon terminals in female rats, using AVP-eGFP and AVP-DREADDs transgenic rats. Strong AVP-eGFP fluorescence in the eME was observed at all oestrus cycle stages in adult female rats but not in male transgenic rats. AVP-eGFP fluorescence in the eME was depleted after bilateral ovariectomy but re-appeared with high-dose 17β-oestradiol. AVP-eGFP fluorescence in the MNCs and PP did not change significantly in most treatments. Peripheral clozapine-N-oxide administration induced AVP-DREADDs neurone activation, causing a significant increase in plasma corticosterone levels in the transgenic rats. These results suggest that stress-induced activation of the hypothalamic-pituitary-adrenal axis may be caused by oestrogen-dependent upregulation of AVP in the eME of female rats.

CRF modulation of central monoaminergic function: Implications for sex differences in alcohol drinking and anxiety

Decades of research have described the importance of corticotropin-releasing factor (CRF) signaling in alcohol addiction, as well as in commonly co-expressed neuropsychiatric diseases, including anxiety and mood disorders. However, CRF signaling can also acutely regulate binge alcohol consumption, anxiety, and affect in non-dependent animals, possibly via modulation of central monoaminergic signaling. We hypothesize that basal CRF tone is particularly high in animals and humans with an inherent propensity for high anxiety and alcohol consumption, and thus these individuals are at increased risk for the development of alcohol use disorder and comorbid neuropsychiatric diseases. The current review focuses on extrahypothalamic CRF circuits, particularly those stemming from the bed nucleus of the stria terminalis (BNST), found to play a role in basal phenotypes, and examines whether the intrinsic hyperactivity of these circuits is sufficient to escalate the expression of these behaviors and steepen the trajectory of development of disease states. We focus our efforts on describing CRF modulation of biogenic amine neuron populations that have widespread projections to the forebrain to modulate behaviors, including alcohol and drug intake, stress reactivity, and anxiety. Further, we review the known sex differences and estradiol modulation of these neuron populations and CRF signaling at their synapses to address the question of whether females are more susceptible to the development of comorbid addiction and stress-related neuropsychiatric diseases because of hyperactive extrahypothalamic CRF circuits compared to males.

Essential Role of Ovarian Hormones in Susceptibility to the Consequences of Witnessing Social Defeat in Female Rats

BACKGROUND

Women are at greater risk than men of developing depression and comorbid disorders such as cardiovascular disease. This enhanced risk begins at puberty and ends following menopause, suggesting a role for ovarian hormones in this sensitivity. Here we used a model of psychosocial witness stress in female rats to determine the stress-induced neurobiological adaptations that underlie stress susceptibility in an ovarian hormone-dependent manner.

METHODS

Intact or ovariectomized (OVX) female rats were exposed to five daily 15-minute witness-stress exposures. Witness-stress-evoked burying, behavioral despair, and anhedonia were measured. Cardiovascular telemetry was combined with plasma measurements of inflammation, epinephrine, and corticosterone as indices of cardiovascular dysfunction. Finally, levels of interleukin-1β and corticotropin-releasing factor were assessed in the central amygdala.

RESULTS

Witness stress produced anxiety-like burying, depressive-like anhedonia, and behavioral despair selectively in intact female rats, which was associated with enhanced sympathetic responses during stress, including increased blood pressure, heart rate, and arrhythmias. Moreover, intact female rats exhibited increases in 12-hour resting systolic pressure and heart rate and reductions in heart rate variability. Notably, OVX female rats remained resilient. Moreover, intact, but not OVX, female rats exposed to witness stress exhibited a sensitized cytokine and epinephrine response to stress and distinct increases in levels of corticotropin-releasing factor and interleukin-1β in the central amygdala.

CONCLUSIONS

Together these data suggest that ovarian hormones play a critical role in the behavioral, inflammatory, and cardiovascular susceptibility to social stress in female rats and reveal putative systems that are sensitized to stress in an ovarian hormone-dependent manner.

Transcriptional regulation of corticotropin-releasing hormone gene in stress response

As a central player of the hypothalamic-pituitary-adrenal (HPA) axis, the corticotropin -releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN) determine the state of HPA axis and play a key role in stress response. Evidence supports that during stress response the transcription and expression of CRH was finely tuned, which involved cis-element-transcriptional factor (TF) interactions and epigenetic mechanisms. Here we reviewed recent progress in CRH transcription regulation from DNA methylation to classic TFs regulation, in which a number of paired receptors were involved. The imbalance of multiple paired receptors in regulating the activity of CRH neurons indicates a possible molecular network mechanisms underlying depression etiology and directs novel therapeutic strategies of depression in the future.

Hypothalamic-pituitary-adrenal and hypothalamic-pituitary-gonadal axes: sex differences in regulation of stress responsivity

Gonadal hormones play a key role in the establishment, activation, and regulation of the hypothalamic-pituitary-adrenal (HPA) axis. By influencing the response and sensitivity to releasing factors, neurotransmitters, and hormones, gonadal steroids help orchestrate the gain of the HPA axis to fine-tune the levels of stress hormones in the general circulation. From early life to adulthood, gonadal steroids can differentially affect the HPA axis, resulting in sex differences in the responsivity of this axis. The HPA axis influences many physiological functions making an organism's response to changes in the environment appropriate for its reproductive status. Although the acute HPA response to stressors is a beneficial response, constant activation of this circuitry by chronic or traumatic stressful episodes may lead to a dysregulation of the HPA axis and cause pathology. Compared to males, female mice and rats show a more robust HPA axis response, as a result of circulating estradiol levels which elevate stress hormone levels during non-threatening situations, and during and after stressors. Fluctuating levels of gonadal steroids in females across the estrous cycle are a major factor contributing to sex differences in the robustness of HPA activity in females compared to males. Moreover, gonadal steroids may also contribute to epigenetic and organizational influences on the HPA axis even before puberty. Correspondingly, crosstalk between the hypothalamic-pituitary-gonadal (HPG) and HPA axes could lead to abnormalities of stress responses. In humans, a dysregulated stress response is one of the most common symptoms seen across many neuropsychiatric disorders, and as a result, such interactions may exacerbate peripheral pathologies. In this review, we discuss the HPA and HPG axes and review how gonadal steroids interact with the HPA axis to regulate the stress circuitry during all stages in life.

Estrogen Receptors Modulation of Anxiety-Like Behavior

Estrogens exert profound effects on the expression of anxiety in humans and rodents; however, the directionality of these effects varies considerably within both clinical and preclinical literature. It is believed that discrepancies regarding the nature of estrogens' effects on anxiety are attributable to the differential effects of specific estrogen receptor (ER) subtypes. In this chapter we will discuss the relative impact on anxiety and anxiety-like behavior of each of the three main ERs: ERα, which has a generally anxiogenic effect, ERβ, which has a generally anxiolytic effect, and the G-protein-coupled ER known as GPR30, which has been found to both increase and decrease anxiety-like behavior. In addition, we will describe the known mechanisms by which these receptor subtypes exert their influence on emotional responses, focusing on the hypothalamic-pituitary-adrenal axis and the oxytocinergic and serotonergic systems. The impact of estrogens on the expression of anxiety is likely the result of their combined effects on all of these neurobiological systems.

Mechanisms by Which 17β-Estradiol (E2) Suppress Neuronal cox-2 Gene Expression

E2 attenuates inflammatory responses by suppressing expression of pro-inflammatory genes. Given that inflammation is increasingly being associated with neurodegenerative and psychiatric processes, we sought to elucidate mechanisms by which E2 down-regulates a component of an inflammatory response, cyclooxygenase- 2 (COX-2) expression. Although inflammatory processes in the brain are usually associated with microglia and astrocytes, we found that the COX-2 gene (cox-2) was expressed in a neuronal context, specifically in an amygdalar cell line (AR-5). Given that COX-2 has been reported to be in neurons in the brain, and that the amygdala is a site involved in neurodegenerative and neuropsychiatric processes, we investigated mechanisms by which E2 could down-regulate cox-2 expression in the AR-5 line. These cells express estrogen receptors alpha (ERα) and beta (ERβ), and as shown here cox-2. At the level of RNA, E2 and the ERβ selective ligand diarylpropionitrile (DPN) both attenuated gene expression, whereas the ERα selective ligand propyl pyrazole triol (PPT) had no effect. Neither ligand increased ERβ at the cox-2 promoter. Rather, DPN decreased promoter occupancy of NF-κB p65 and histone 4 (H4) acetylation. Treatment with the non-specific HDAC inhibitor Trichostatin A (TSA) counteracted DPN's repressive effects on cox-2 expression. In keeping with the TSA effect, E2 and DPN increased histone deacetylase one (HDAC1) and switch-independent 3A (Sin3A) promoter occupancy. Lastly, even though E2 increased CpG methylation, DPN did not. Taken together, the pharmacological data indicate that ERβ contributes to neuronal cox-2 expression, as measured by RNA levels. Furthermore, ER ligands lead to increased recruitment of HDAC1, Sin3A and a concomitant reduction of p65 occupancy and Ac-H4 levels. None of the events, however, are associated with a significant recruitment of ERβ at the promoter. Thus, ERβ directs recruitment to the cox-2 promoter, but does so in the absence of being recruited itself.

Stress is a principal factor that promotes tobacco use in females

Tobacco use is a major economic and health problem. It is particularly concerning that women consume more tobacco products, have a more difficult time quitting smoking, and are less likely to benefit from smoking cessation therapy than men. As a result, women are at higher risk of developing tobacco-related diseases. Clinical evidence suggests that women are more susceptible to anxiety disorders, and are more likely to smoke in order to cope with stress than men. During smoking abstinence, women experience more intense anxiety than men and report that the anxiety-reducing effects of smoking are the main reason for their continued tobacco use and relapse. Consistent with this, pre-clinical studies using rodent models suggest that females display more intense stress during nicotine withdrawal than males. This review posits that in women, stress is a principal factor that promotes the initiation of tobacco use and relapse behavior during abstinence. Studies are reviewed at both the clinical and pre-clinical levels to provide support for our hypothesis that stress plays a central role in promoting tobacco use vulnerability in females. The clinical implications of this work are also considered with regard to treatment approaches and the need for more research to help reduce health disparities produced by tobacco use in women.

The Content of Thyroid Hormone Receptor α in Ewe Kisspeptin Neurones is not Season-Dependent

Seasonal reproduction is grounded in several mechanisms, among which are plasticity in both hormone synthesis and neuronal networks. Increased daylength on long days (LD) translates into local tri-iodothyronin (T3) production in the mediobasal hypothalamus that will enable the transition to the anoestrus season in sheep. The photoperiod also strongly affects the content of kisspeptin (Kiss), a hypothalamic neuropeptide exerting a potent stimulatory effect on gonadotrophin-releasing hormone release. Our hypothesis was that T3 directly inhibits Kiss release during LD. Using double immunocytochemistry, we first searched for coexpression of thyroid hormone receptor (THR)α in Kiss neurones in ewes with an active or inactive gonadotrophic axis. In both the preoptic area and the arcuate nucleus, most Kiss neurones were labelled by THR antibody under both physiological/photoperiodic conditions. These results suggest thyroid hormones may affect Kiss synthesis and release all through the year. We then attempted to assess the influence of T3 on Kiss content in hypothalamic explants sampled from ewes with an active gonadotrophic axis. Kiss produced by hypothalamic explants cultured with different doses of T3 (300 or 600 pg) and subjected to different times of incubation (2 or 24 h) was measured. No significant effects of T3 on Kiss tissular content were observed for the two doses of T3 and for the two incubation times. In light of these findings, potential reasons for the divergent effects of thyroid hormones on Kiss content are discussed. Our data emphasise that the effects of thyroid hormone on Kiss synthesis are not one-sided and may affect a wide range of functions.

To quit or not: Vulnerability of women to smoking tobacco

Tobacco smoking is currently on the rise among women, and can pose a greater health risk. In order to understand the nature of the increase in smoking prevalence among women, we focused on the vulnerability of women to smoking behaviors--smoking cessation or tobacco addiction--and performed a systematic review of the socioeconomic and intrinsic factors as well as tobacco ingredients that affect women's susceptibility to smoking tobacco. We observed that nicotine and other tobacco components including cocoa-relatives, licorice products, and menthol aggravate tobacco addiction in women rather than in men. Various genetic and epigenetic alterations in dopamine pathway and the pharmaco-kinetics and -dynamic factors of nicotine also showed potential evidences for high susceptibility to tobacco addiction in women. Therefore, we suggest systemic approaches to prevent tobacco smoking-related health risks, considering gene-environment-gender interaction.

Aging and Loss of Circulating 17β-Estradiol Alters the Alternative Splicing of ERβ in the Female Rat Brain

Loss of circulating 17β-estradiol (E2) that occurs during menopause can have detrimental effects on cognitive function. The efficacy of hormone replacement therapy declines as women become farther removed from the menopausal transition, yet the molecular mechanisms underlying this age-related switch in E2 efficacy are unknown. We hypothesized that aging and varying lengths of E2 deprivation alters the ratio of alternatively spliced estrogen receptor (ER)β isoforms in the brain of female rats. Further, we tested whether changes in global transcriptional activity and splicing kinetics regulate the alternative splicing of ERβ. Our results revealed brain region-specific changes in ERβ alternative splicing in both aging and E2-deprivation paradigms and showed that ERβ could mediate E2-induced alternative splicing. Global transcriptional activity, as measured by phosphorylated RNA polymerase II, was also regulated by age and E2 in specific brain regions. Finally, we show that inhibition of topoisomerase I resulted in increased ERβ2 splice variant expression.

Dynamics of appetite-mediated gene expression in daidzein-fed female rats in the meal-feeding method

We previously found that daidzein decreased food intake in female rats. The present study aimed to elucidate the relationship between dynamics of appetite-mediated neuropeptides and the anorectic effect of daidzein. We examined appetite-mediated gene expression in the hypothalamus and small intestine during the 3 meals per day feeding method. Daidzein had an anorectic effect specifically at the second feeding. Neuropeptide-Y (NPY) and galanin mRNA levels in the hypothalamus were significantly higher after feeding in the control but not in the daidzein group, suggesting that daidzein attenuated the postprandial increase in NPY and galanin expression. The daidzein group had higher corticotrophin-releasing hormone (CRH) mRNA levels in the hypothalamus after feeding, and increased cholelcystokinin (CCK) mRNA levels in the small intestine, suggesting that CCK is involved in the hypothalamic regulation of this　anorectic effect. Therefore, daidzein may induce anorexia by suppressing expression of NPY and galanin and increasing expression of CRH in the hypothalamus.

Gonadal steroid hormones and the hypothalamo-pituitary-adrenal axis

The hypothalamo-pituitary-adrenal (HPA) axis represents a complex neuroendocrine feedback loop controlling the secretion of adrenal glucocorticoid hormones. Central to its function is the paraventricular nucleus of the hypothalamus (PVN) where neurons expressing corticotropin releasing factor reside. These HPA motor neurons are a primary site of integration leading to graded endocrine responses to physical and psychological stressors. An important regulatory factor that must be considered, prior to generating an appropriate response is the animal's reproductive status. Thus, PVN neurons express androgen and estrogen receptors and receive input from sites that also express these receptors. Consequently, changes in reproduction and gonadal steroid levels modulate the stress response and this underlies sex differences in HPA axis function. This review examines the make up of the HPA axis and hypothalamo-pituitary-gonadal (HPG) axis and the interactions between the two that should be considered when exploring normal and pathological responses to environmental stressors.

V. Gender determines ACTH recovery from hypercortisolemia in healthy older humans

OBJECTIVE

Available clinical data raise the possibility that stress-adaptive mechanisms differ by gender. However, this notion has not been rigorously tested in relation to cortisol-mediated negative feedback.

MATERIALS/METHODS

Degree of ACTH inhibition during and recovery from an experimental cortisol clamp was tested in 20 healthy older subjects (age 60±2.2 y). Volunteers received oral placebo or ketoconazole (KTCZ) to inhibit adrenal steroidogenesis along with i.v. infusions of saline or a low vs high physiological dose of cortisol in a prospectively randomized double-blind, placebo-controlled design. ACTH and cortisol concentrations were measured every 10 min during the feedback-clamp phase and thereafter (recovery or escape phase). Corticosteroid-binding globulin (CBG) was measured, and free cortisol concentrations were calculated.

RESULTS

Gender did not determine mean ACTH concentrations during the saline or cortisol feedback-clamp phases per se. However, women had markedly impaired ACTH recovery after stopping both low- and high-dose cortisol infusions compared with men (P=0.005, KTCZ/low-dose cortisol arm; and P=0.006, KTCZ/high-dose cortisol arm). Decreased ACTH recovery in women was accompanied by lower total and free cortisol concentrations, pointing to heightened feedback inhibition of hypothalamo-pituitary drive of ACTH secretion as the main mechanism.

CONCLUSIONS

In summary, gender or a factor related to gender, such as sex steroids or body composition, determines recovery of ACTH secretion from cortisol-enforced negative feedback. Attenuated ACTH recovery in post-menopausal women may have relevance to sex differences in stress-related adaptations.

Reproductive experience alters neural and behavioural responses to acute oestrogen receptor α activation

Reproductive experience (i.e. parturition and lactation) leads to persistent alterations in anxiety-like behaviour that are influenced by the oestrous cycle. We recently found that repeated administration of the selective oestrogen receptors (ER)α agonist propyl-pyrazole triol (PPT) results in anxiolytic-like behaviours on the elevated plus maze (EPM) in primiparous (but not nulliparous) female rats. The present study examined the effects of the acute administration of PPT on EPM behaviour in primiparous and aged-matched, nulliparous female rats. In addition, corticosterone secretion, corticotrophin-releasing hormone (CRH) gene expression and expression of the immediate early gene product Fos in the paraventricular nucleus (PVN) and amygdala were measured either after EPM testing or in home cage controls. Acute PPT administration significantly modified EPM behaviour as a function of reproductive experience, with nulliparous females tending toward increased anxiety-like behaviours and primiparous females tending toward decreased anxiety-like behaviours. In home cage controls, PPT increased corticosterone secretion in all females; however, both vehicle- and PPT-treated, primiparous females had reduced corticosterone levels compared to their nulliparous counterparts. Significant effects of PPT on CRH mRNA within the PVN were observed after the administration of PPT but only in primiparous females tested on the EPM. PPT also increased Fos expression within the PVN of EPM-exposed females; however, both vehicle- and PPT-treated primiparous females had reduced Fos expression compared to nulliparous females. In the amygdala, PPT increased Fos immunoreactivity in the central but not the medial or basolateral amygdala, although these effects were only observed in home cage females. Additionally, both vehicle- and PPT-treated home cage, primiparous females had increased Fos in the central nucleus of the amygdala compared to nulliparous controls. Overall, these data demonstrate that reproductive experience alters the behavioural response to acute ERα activation. Moreover, the findings suggest that central regulation of the hypothalamic-adrenal-pituitary axis is modified as a consequence of reproductive experience.

Estrogen signaling and the aging brain: context-dependent considerations for postmenopausal hormone therapy

Recent clinical studies have spurred rigorous debate about the benefits of hormone therapy (HT) for postmenopausal women. Controversy first emerged based on a sharp increase in the risk of cardiovascular disease in participants of the Women's Health Initiative (WHI) studies, suggesting that decades of empirical research in animal models was not necessarily applicable to humans. However, a reexamination of the data from the WHI studies suggests that the timing of HT might be a critical factor and that advanced age and/or length of estrogen deprivation might alter the body's ability to respond to estrogens. Dichotomous estrogenic effects are mediated primarily by the actions of two high-affinity estrogen receptors alpha and beta (ER α & ER β ). The expression of the ERs can be overlapping or distinct, dependent upon brain region, sex, age, and exposure to hormone, and, during the time of menopause, there may be changes in receptor expression profiles, post-translational modifications, and protein:protein interactions that could lead to a completely different environment for E2 to exert its effects. In this review, factors affecting estrogen-signaling processes will be discussed with particular attention paid to the expression and transcriptional actions of ER β in brain regions that regulate cognition and affect.

Dexamethasone induces a putative repressor complex and chromatin modifications in the CRH promoter

Glucocorticoids down-regulate expression of hypothalamic CRH; however, mechanisms by which they do so are not fully understood. The proximal promoter cAMP response element, negative glucocorticoid response element (nGRE), and methylated CpG islands all play a role in crh down-regulation. Dexamethasone (Dex)-repressed crh expression is associated with glucocorticoid receptor (GR) and histone deacetylase 1 (HDAC1) recruitment to the region of the crh promoter. Given that HDAC1 may be present in methylated CpG binding protein 2 (MeCP2) complexes, and that MeCP2 is known to play a role in regulating crh expression, we sought to determine whether or not HDAC1 and/or MeCP2 could interact with the GR. Dex enhanced GR interactions with both proteins. Glucocorticoid regulation of crh has also been associated with CpG methylation; thus we assessed whether GR could interact with a DNA methyltransferase (DnMT). Indeed, the GR interacted with DnMT3b, but not DnMT3a. In addition, Dex-induced occupancy of the crh promoter by HDAC1, MeCP2, and DnMT3b was associated with an increased level of promoter methylation, which appeared to be CpG site specific. Lastly, to extend previous assessment of chromatin modifications in this promoter region, the degree of histone methylation was measured. Dex increased trimethylation of histone 3-lysine 9, a marker of gene suppression; however, levels of di- and trimethylated histone 3-lysine 4, markers of gene activation, were not significantly changed. Taken together, the data suggest that Dex-mediated crh suppression involves formation of a repressor complex consisting of GR, MeCP2, and HDAC1, recruitment of DnMT3b, and associated changes in proximal promoter CpG methylation.

A mechanistic hypothesis of the factors that enhance vulnerability to nicotine use in females

Women are particularly more vulnerable to tobacco use than men. This review proposes a unifying hypothesis that females experience greater rewarding effects of nicotine and more intense stress produced by withdrawal than males. We also provide a neural framework whereby estrogen promotes greater rewarding effects of nicotine in females via enhanced dopamine release in the nucleus accumbens (NAcc). During withdrawal, we suggest that corticotropin-releasing factor (CRF) stress systems are sensitized and promote a greater suppression of dopamine release in the NAcc of females versus males. Taken together, females display enhanced nicotine reward via estrogen and amplified effects of withdrawal via stress systems. Although this framework focuses on sex differences in adult rats, it is also applied to adolescent females who display enhanced rewarding effects of nicotine, but reduced effects of withdrawal from this drug. Since females experience strong rewarding effects of nicotine, a clinical implication of our hypothesis is that specific strategies to prevent smoking initiation among females are critical. Also, anxiolytic medications may be more effective in females that experience intense stress during withdrawal. Furthermore, medications that target withdrawal should not be applied in a unilateral manner across age and sex, given that nicotine withdrawal is lower during adolescence. This review highlights key factors that promote nicotine use in females, and future studies on sex-dependent interactions of stress and reward systems are needed to test our mechanistic hypotheses. Future studies in this area will have important translational value toward reducing health disparities produced by nicotine use in females. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

Hormonal contraceptive use diminishes salivary cortisol response to psychosocial stress and naltrexone in healthy women

The use of hormonal contraception (HC) may affect salivary cortisol levels at rest and in response to a pharmacological or stress challenge. Therefore, the current study used a secondary data analysis to investigate the effect of HC on salivary cortisol levels in response to the mu-opioid receptor antagonist naltrexone and a psychosocial stressor, and also across the diurnal curve. Two hundred and nine women (n=72 using hormonal contraception; HC+) completed a two-session stress response study that consisted of a stress day, in which they were exposed to public speaking and mental arithmetic, and a rest day, in which unstimulated cortisol levels were measured to assess the diurnal rhythm. A subset of seventy women (n=24 HC+) also completed a second study in which they were administered oral naltrexone (50mg) or placebo in a randomized, placebo-controlled, double blind fashion. Women who were HC+ had a significantly reduced salivary cortisol response to both the psychosocial stressor (p<0.001) and naltrexone (p<0.05) compared to HC- women. Additionally, HC+ women had a significantly altered morning diurnal cortisol rhythm (p<0.01), with a delayed peak and higher overall levels. The results of the current study confirm that HC attenuates salivary cortisol response to a psychosocial stressor and mu-opioid receptor antagonism, and also alters the morning diurnal cortisol curve.

Behavioral, Biochemical, and Molecular Indices of Stress are Enhanced in Female Versus Male Rats Experiencing Nicotine Withdrawal

Stress is a major factor that promotes tobacco use and relapse during withdrawal. Although women are more vulnerable to tobacco use than men, the manner in which stress contributes to tobacco use in women versus men is unclear. Thus, the goal of this study was to compare behavioral and biological indices of stress in male and female rats during nicotine withdrawal. Since the effects of nicotine withdrawal are age-dependent, this study also included adolescent rats. An initial study was conducted to provide comparable nicotine doses across age and sex during nicotine exposure and withdrawal. Rats received sham surgery or an osmotic pump that delivered nicotine. After 14 days of nicotine, the pumps were removed and controls received a sham surgery. Twenty-four hours later, anxiety-like behavior and plasma corticosterone were assessed. The nucleus accumbens (NAcc), amygdala, and hypothalamus were examined for changes in corticotropin-releasing factor (CRF) gene expression. In order to differentiate the effects of nicotine withdrawal from exposure to nicotine, a cohort of rats did not have their pumps removed. The major finding is that during nicotine withdrawal, adult females display higher levels of anxiety-like behavior, plasma corticosterone, and CRF mRNA expression in the NAcc relative to adult males. However, during nicotine exposure, adult males exhibited higher levels of corticosterone and CRF mRNA in the amygdala relative to females. Adolescents displayed less nicotine withdrawal than adults. Moreover, adolescent males displayed an increase in anxiety-like behavior and an up-regulation of CRF mRNA in the amygdala during nicotine exposure and withdrawal. These findings are likely related to stress produced by the high doses of nicotine that were administered to adolescents to produce equivalent levels of cotinine as adults. In conclusion, these findings suggest that intense stress produced by nicotine withdrawal may contribute to tobacco use in women.

The ERβ ligand 5α-androstane, 3β,17β-diol (3β-diol) regulates hypothalamic oxytocin (Oxt) gene expression

The endocrine component of the stress response is regulated by glucocorticoids and sex steroids. Testosterone down-regulates hypothalamic-pituitary-adrenal (HPA) axis activity; however, the mechanisms by which it does so are poorly understood. A candidate testosterone target is the oxytocin gene (Oxt), given that it too inhibits HPA activity. Within the paraventricular nucleus of the hypothalamus, oxytocinergic neurons involved in regulating the stress response do not express androgen receptors but do express estrogen receptor-β (ERβ), which binds the dihydrotestosterone metabolite 3β,17β-diol (3β-diol). Testosterone regulation of the HPA axis thus appears to involve the conversion to the ERβ-selective ligand 5α-androstane, 3β-diol. To study mechanisms by which 3β-diol could regulate Oxt expression, we used a hypothalamic neuronal cell line derived from embryonic mice that expresses Oxt constitutively and compared 3β-diol with estradiol (E2) effects. E2 and 3β-diol elicited a phasic response in Oxt mRNA levels. In the presence of either ligand, Oxt mRNA levels were increased for at least 60 min and returned to baseline by 2 h. ERβ occupancy preceded an increase in Oxt mRNA levels in the presence of 3β-diol but not E2. In tandem with ERβ occupancy, 3β-diol increased occupancy of the Oxt promoter by cAMP response element-binding protein and steroid receptor coactivator-1 at 30 min. At the same time, 3β-diol led to the increased acetylation of histone H4 but not H3. Taken together, the data suggest that in the presence of 3β-diol, ERβ associates with cAMP response element-binding protein and steroid receptor coactivator-1 to form a functional complex that drives Oxt gene expression.

Corticotropin-releasing factor modulation of forebrain GABAergic transmission has a pivotal role in the expression of anabolic steroid-induced anxiety in the female mouse

Increased anxiety is commonly observed in individuals who illicitly administer anabolic androgenic steroids (AAS). Behavioral effects of steroid abuse have become an increasing concern in adults and adolescents of both sexes. The dorsolateral bed nucleus of the stria terminalis (dlBnST) has a critical role in the expression of diffuse anxiety and is a key site of action for the anxiogenic neuromodulator, corticotropin releasing factor (CRF). Here we demonstrate that chronic, but not acute, exposure of female mice during adolescence to AAS augments anxiety-like behaviors; effects that were blocked by central infusion of the CRF receptor type 1 antagonist, antalarmin. AAS treatment selectively increased action potential (AP) firing in neurons of the central amygdala (CeA) that project to the dlBnST, increased the frequency of GABA(A) receptor-mediated spontaneous inhibitory postsynaptic currents (sIPSCs) in dlBnST target neurons, and decreased both c-FOS immunoreactivity (IR) and AP frequency in these postsynaptic cells. Acute application of antalarmin abrogated the enhancement of GABAergic inhibition induced by chronic AAS exposure whereas application of CRF to brain slices of naïve mice mimicked the actions of this treatment. These results, in concert with previous data demonstrating that chronic AAS treatment results in enhanced levels of CRF mRNA in the CeA and increased CRF-IR in the dlBnST neuropil, are consistent with a mechanism in which the enhanced anxiety elicited by chronic AAS exposure involves augmented inhibitory activity of CeA afferents to the dlBnST and CRF-dependent enhancement of GABAergic inhibition in this brain region.

HOXC10 is overexpressed in breast cancer and transcriptionally regulated by estrogen via involvement of histone methylases MLL3 and MLL4

HOXC10 is a critical player in the development of spinal cord, formation of neurons, and associated with human leukemia. We found that HOXC10 is overexpressed in breast cancer and transcriptionally regulated by estrogen (17β-estradiol, E(2)). The HOXC10 promoter contains several estrogen response elements (ERE1-7, half-sites). A luciferase-based reporter assay showed that ERE1 and ERE6 of HOXC10 promoter are E(2) responsive. ERα and ERβ play critical roles in E(2)-mediated activation of HOXC10. Knockdown of ERα and ERβ downregulated E(2)-induced HOXC10 expression. ERα and ERβ bind to ERE1 and ERE6 regions in an E(2)-dependent manner. Additionally, knockdown of histone methylases MLL3 and MLL4 (but not MLL1 and MLL2) diminished E(2)-induced expression of HOXC10. MLL3 and MLL4 were bound to the ERE1 and ERE6 regions of HOXC10 promoter in an E(2)-dependent manner. Overall, we demonstrated that HOXC10 is overexpressed in breast cancer, and it is an E(2)-responsive gene. Histone methylases MLL3 and MLL4, along with ERs, regulate HOXC10 gene expression in the presence of E(2).

Activation of estrogen receptor α by raloxifene through an activating protein-1-dependent tethering mechanism in human cervical epithelial cancer cells: a role for c-Jun N-terminal kinase

Nuclear estrogen receptor α (ERα) regulates target gene expression in response to ligands through two distinct mechanisms: direct binding to DNA and indirect tethering through other DNA-bound transcription factors, such as AP-1. In the studies described herein, we examined the molecular mechanisms underlying the activation of ERα in the AP-1 tethering pathway by the selective estrogen receptor modulator (SERM) raloxifene (Ral). Our results with the MMP1 and PRUNE genes indicate that the c-Fos component of the AP-1 tethering factor and the c-Jun N-terminal kinase 1 (JNK1) are constitutively bound at the promoter regions prior to Ral exposure. Ral then promotes the binding of ERα at the promoter in a c-Fos-dependent manner. Interestingly, we found that JNK1 enzymatic activity is required for Ral-dependent gene activation through ERα. Our results suggest that one role for Ral-dependent recruitment of ERα to the AP-1 binding site is to stimulate JNK1 enzymatic activity. Alternatively, Ral-occupied ERα might recruit protein substrates to promoter-bound JNK1 without any change in JNK1 activity. Collectively, our studies have revealed a new role for JNK1 in determining gene regulatory outcomes by ERα.

Rapid nongenomic effects of oestradiol on gonadotrophin-releasing hormone neurones

That oestradiol can have both negative- and positive-feedback actions upon the release of gonadotrophin-releasing hormone (GnRH) has been understood for decades. The vast majority of studies have investigated the effects of in vivo oestrogen administration. In the past decade, evidence has accumulated in many neuronal and non-neuronal systems indicating that, in addition to traditional genomic action via transcription factor receptors, steroids can also initiate effects rapidly via signalling cascades typically associated with the cell membrane. Here, we review work examining the rapid actions of oestradiol on GnRH neurones, addressing the questions of dose dependence, receptor subtypes, signalling cascades and intrinsic and synaptic properties that are rapidly modulated by this steroid.

Estrogen receptors and the regulation of neural stress responses

It is now well established that estrogens can influence a panoply of physiological and behavioral functions. In many instances, the effects of estrogens are mediated by the 'classical' actions of two different estrogen receptors (ERs), ERα or ERβ. ERα and ERβ appear to have opposing actions in the control of stress responses and modulate different neurotransmitter or neuropeptide systems. Studies elucidating the molecular mechanisms for such regulatory processes are currently in progress. Furthermore, the use of ERα and ERβ knockout mouse lines has allowed the exploration of the importance of these receptors in behavioral responses such as anxiety-like and depressive-like behaviors. This review examines some of the recent advances in our knowledge of hormonal control of neuroendocrine and behavioral responses to stress and underscore the importance of these receptors as future therapeutic targets for control of stress-related signaling pathways.

The molecular physiology of CRH neurons

Corticotropin releasing hormone (CRH) is essential for stress adaptation by mediating hypothalamic-pituitary-adrenal (HPA) axis, behavioral and autonomic responses to stress. Activation of CRH neurons depends on neural afferents from the brain stem and limbic system, leading to sequential CRH release and synthesis. CRH transcription is required to restore mRNA and peptide levels, but termination of the response is essential to prevent pathology associated with chronic elevations of CRH and HPA axis activity. Inhibitory feedback mediated by glucocorticoids and intracellular production of the repressor, Inducible Cyclic AMP Early Repressor (ICER), limit the magnitude and duration of CRH neuronal activation. Induction of CRH transcription is mediated by the cyclic AMP/protein kinase A/cyclic AMP responsive element binding protein (CREB)-dependent pathways, and requires cyclic AMP-dependent nuclear translocation of the CREB co-activator, Transducer of Regulated CREB activity (TORC). This article reviews current knowledge on the mechanisms regulating CRH neuron activity.

Variations in maternal care alter corticosterone and 17beta-estradiol levels, estrous cycle and folliculogenesis and stimulate the expression of estrogen receptors alpha and beta in the ovaries of UCh rats

BACKGROUND

Variations in maternal care are associated with neonatal stress, hormonal disturbances and reproductive injuries during adulthood. However, the effects of these variations on sex hormones and steroid receptors during ovary development remain undetermined. This study aimed to investigate whether variations in maternal care are able to influence the hormonal profile, follicular dynamics and expression of AR, ER-alpha and ER-beta in the ovaries of UCh rat offspring.

METHODS

Twenty-four adult UCh rats, aged 120 days, were randomly divided into two groups (UChA and UChB) and mated. Maternal care was assessed from birth (day 0) to the 10th postnatal day (PND). In adulthood, twenty adult female rats (UChA and UChB offspring; n = 10/group), aged 120 days, were euthanized by decapitation during the morning estrus.

RESULTS

UChA females (providing high maternal care) more frequently displayed the behaviors of carrying pups, as well as licking/grooming and arched back nursing cares. Also, mothers providing high care had elevated corticosterone levels. Additionally, offspring receiving low maternal care showed the highest estrous cycle duration, increased corticosterone and 17beta-estradiol levels, overexpression of receptors ER-alpha and ER-beta, increased numbers of primordial, antral and mature follicles and accentuated granulosa cell proliferation.

CONCLUSIONS

Our study suggests that low maternal care alters corticosterone and 17beta-estradiol levels, disrupting the estrous cycle and folliculogenesis and differentially regulating the expression of ER-alpha and ER-beta in the ovaries of adult rats.

CBP mediates NF-κB-dependent histone acetylation and estrogen receptor recruitment to an estrogen response element in the BIRC3 promoter

Estrogen receptor (ER) and NF-κB are transcription factors with profound effects on breast cancer cell proliferation and survival. While many studies demonstrate that ER and NF-κB can repress each other, we previously identified a gene signature that is synergistically upregulated by these two factors in more aggressive luminal B breast tumors. Herein, we examine a novel mechanism of cross talk between ER and NF-κB that results in the upregulation of the antiapoptotic gene BIRC3 (also known as cIAP2). We demonstrate that NF-κB, acting through two response elements, is required for ER recruitment to an adjacent estrogen response element (ERE) in the BIRC3 promoter. This effect is accompanied by a major increase in NF-κB-dependent histone acetylation around the ERE. Interestingly, CBP, a histone acetyltransferase previously implicated in repressive interactions between ER and NF-κB, plays a permissive role by promoting histone acetylation and ER recruitment, as well as enhanced expression of BIRC3. These findings suggest a new gene regulatory mechanism by which inflammation and NF-κB activation can influence ER recruitment to inherently inactive ER binding sites. This fine-tuning mechanism may explain how two factors that generally repress each other's activity may work together on certain genes to promote breast cancer cell survival and tumor progression.