Blockade of estrogen by hormonal contraceptives impairs fear extinction in female rats and women

Reduced threat avoidance but increased stress induced approach bias in women taking oral contraceptives

Recent research has increasingly acknowledged the impact of oral contraceptives on affective behavior and stress responses; however, the underlying mechanisms are still not well understood. Studies have previously shown that steroid hormones modulate automatic approach and avoidance behavior. Here, we thus investigated the effects of oral contraceptives on approach and avoidance behavior and whether these effects are modulated by stress. The study comprised 130 female participants, half of whom were using oral contraceptives, while the other half were not using any hormonal contraception (NC). The participants completed the Approach Avoidance Task (AAT), which measures automatic approach and avoidance behavior to socio-affective signals. The AAT was run once before and once after a stress manipulation using the Socially Evaluated Cold Pressor Test. OC users showed absent avoidance behavior to social threat signals and a stress-induced increase in approach behavior to positive social signals. The latter was found in particular in women taking androgenic acting OC, demonstrating that different OC preparations need to be taken into account in research on OC effects. However, OC and NC group did not differ in their cortisol stress response. Overall, the results suggest that OC usage impacts on approach and avoidance behavior to social signals, which might also contribute to the development of affective side effects.

Treatment Approaches for Posttraumatic Stress Disorder Derived from Basic Research on Fear Extinction

This brief review article will describe treatment approaches for posttraumatic stress disorder (PTSD) based on findings from basic research. The focus of this review will be fear conditioning and extinction models, which provide a translational model of PTSD that can help translate basic research in non-human animals through well-controlled trials confirming the efficacy of treatment approaches in humans with PTSD such as prolonged exposure therapy. Specific cognitive aspects of fear extinction processes, including consolidation and reconsolidation, are reviewed along with behavioral and pharmacological treatment strategies based on basic research in these areas including attempts to prevent the development of PTSD as well as the treatment of chronic PTSD. Pharmacological, behavioral, and device-based augmentation strategies of PTSD treatment based in basic science findings are reviewed, including those that disrupt noradrenergic receptor processes, medications that act on NMDA receptors, physical exercise, cannabinoids, estradiol, dexamethasone, yohimbine, losartan, dopamine, and MDMA, along with the evidence for their efficacy in human clinical samples. While fear extinction provides an exciting translational opportunity to improve PTSD based on basic science findings, we review limitations and challenges of the extant literature as well as future directions.

Conceptualizing disparities and differences in the psychobiology of traumatic stress

Understanding biological pathways that mediate trauma-related psychopathology is a major goal for traumatic stress studies. There is growing interest in studying differences in neural, physiological, and behavioral correlates of traumatic stress across demographic groups (e.g., sex/gender, race/ethnicity). However, challenges remain in how to appropriately conceptualize the source, mechanisms, and practical utility of between-group variation. The present brief conceptual review discusses ethnicity, race, and sex/gender-related variability relevant to understanding the psychobiology of traumatic stress in the context of traumatic stress studies. We discuss recent evidence related to socioenvironmental influences on ethnoracial variability in the brain and behavior relevant to traumatic stress, as well as sex/gender associations in neurophysiology that may contribute to the development of adverse posttraumatic sequelae. We further synthesize these findings by discussing intersectional influences of sex/gender- and race/ethnicity-related factors on trauma-related physical and mental health outcomes. The present review provides an important foundation for future research on disparities and individual differences in traumatic stress to move the field toward more effective assessment and treatment approaches.

Estrogen receptor beta signaling enhances extinction memory recall for heroin-conditioned cues in a sex- and region-specific manner

Return to use, or relapse, is a major challenge in the treatment of opioid use disorder (OUD). Relapse can be precipitated by several factors, including exposure to drug-conditioned cues. Identifying successful treatments to mitigate cue-induced relapse has been challenging, perhaps due to extinction memory recall (EMR) deficits. Previously, inhibition of estradiol (E2) signaling in the basolateral amygdala (BLA) impaired heroin-cue EMR. This effect was recapitulated by antagonism of BLA estrogen receptors (ER) in a sex-specific manner such that blocking ERα in males, but ERβ in females, impaired EMR. However, it is unclear whether increased E2 signaling, in the BLA or systemically, enhances heroin-cue EMR. We hypothesized that ERβ agonism would enhance heroin-cue EMR in a sex- and region-specific manner. To determine the capacity of E2 signaling to improve EMR, we pharmacologically manipulated ERβ across several translationally designed experiments. First, male and female rats acquired heroin or sucrose self-administration. Next, during a cued extinction session, we administered diarylpropionitrile (DPN, an ERβ agonist) and tested anxiety-like behavior on an open field. Subsequently, we assessed EMR in a cue-induced reinstatement test and, finally, measured ERβ expression in several brain regions. Across all experiments, females took more heroin and sucrose than males and had greater responses during heroin-cued extinction. Administration of DPN in the BLA enhanced EMR in females only, driven by ERβ's impacts on memory consolidation. Interestingly, however, systemic DPN administration improved EMR for heroin cues in both sexes across several different tests, but did not impact sucrose-cue EMR. Immunohistochemical analysis of ERβ expression across several different brain regions showed that females only had greater expression of ERβ in the basal nucleus of the BLA. Here, in several preclinical experiments, we demonstrated that ERβ agonism enhances heroin-cue EMR and has potential utility in combatting cue-induced relapse.

Ketamine's Amelioration of Fear Extinction in Adolescent Male Mice Is Associated with the Activation of the Hippocampal Akt-mTOR-GluA1 Pathway

Fear-related disorders, including post-traumatic stress disorder (PTSD), and anxiety disorders are pervasive psychiatric conditions marked by persistent fear, stemming from its dysregulated acquisition and extinction. The primary treatment for these disorders, exposure therapy (ET), relies heavily on fear extinction (FE) principles. Adolescence, a vulnerable period for developing psychiatric disorders, is characterized by neurobiological changes in the fear circuitry, leading to impaired FE and increased susceptibility to relapse following ET. Ketamine, known for relieving anxiety and reducing PTSD symptoms, influences fear-related learning processes and synaptic plasticity across the fear circuitry. Our study aimed to investigate the effects of ketamine (10 mg/kg) on FE in adolescent male C57 BL/6 mice at the behavioral and molecular levels. We analyzed the protein and gene expression of synaptic plasticity markers in the hippocampus (HPC) and prefrontal cortex (PFC) and sought to identify neural correlates associated with ketamine's effects on adolescent extinction learning. Ketamine ameliorated FE in the adolescent males, likely affecting the consolidation and/or recall of extinction memory. Ketamine also increased the Akt and mTOR activity and the GluA1 and GluN2A levels in the HPC and upregulated BDNF exon IV mRNA expression in the HPC and PFC of the fear-extinguished mice. Furthermore, ketamine increased the c-Fos expression in specific brain regions, including the ventral HPC (vHPC) and the left infralimbic ventromedial PFC (IL vmPFC). Providing a comprehensive exploration of ketamine's mechanisms in adolescent FE, our study suggests that ketamine's effects on FE in adolescent males are associated with the activation of hippocampal Akt-mTOR-GluA1 signaling, with the vHPC and the left IL vmPFC as the proposed neural correlates.

The impact of extinction timing on pre-extinction arousal and subsequent return of fear

Exposure-based therapy is effective in treating anxiety, but a return of fear in the form of relapse is common. Exposure is based on the extinction of Pavlovian fear conditioning. Both animal and human studies point to increased arousal during immediate compared to delayed extinction (>+24 h), which presumably impairs extinction learning and increases the subsequent return of fear. Impaired extinction learning under arousal might interfere with psychotherapeutic interventions. The aim of the present study was to investigate whether arousal before extinction differs between extinction groups and whether arousal before extinction predicts the return of fear in a later (retention) test. As a highlight, both the time between fear acquisition and extinction (immediate vs. delayed) and the time between extinction and test (early vs. late test) were systematically varied. We performed follow-up analyses on data from 103 young, healthy participants to test the above hypotheses. Subjective arousal ratings and physiological arousal measures of sympathetic and hypothalamic pituitary adrenal axis activation (tonic skin conductance and salivary cortisol) were collected. Increased pre-extinction arousal in the immediate extinction group was only confirmed for subjective arousal. In linear regression analyses, none of the arousal measures predicted a significant return of fear in the different experimental groups. Only when we aggregated across the two test groups, tonic skin conductance at the onset of extinction predicted the return of fear in skin conductance responses. The overall results provide little evidence that pre-extinction arousal affects subsequent extinction learning and memory. In terms of clinical relevance, there is no clear evidence that exposure could be improved by reducing subjective or physiological arousal.

The link between daily affective complexity and anxiety is altered by oral contraceptive use

Affective complexity - the unique ways in which individuals' emotions covary and differentiate - is an important aspect of internalizing problems. For instance, daily affective complexity has been linked to anxiety increases in women and to decreases in men. The mechanisms underlying this gender difference have not been widely investigated, but a role for ovarian hormones is likely. Research on oral contraceptives (OCs) provides promising insights into such mechanisms, as OCs suppress endogenous ovarian hormone production and vary in exogenous hormone formulations. Thus, the goal of this study was to examine links between daily affective complexity and internalizing problems in OC users (n = 84), focusing on dimensionally-assessed anxiety, and to investigate whether the links varied by pill formulation. Affective complexity was operationalized as number of factors for each person, as estimated by p-technique (i.e., person-specific factor analysis) of 75-day intensive longitudinal data. There was not a relation between affective complexity and anxiety in OC users, and this did not depend on OC pill formulation (i.e., estrogenic, progestational, or androgenic activities). Thus, OC use may blunt the relation between affective complexity and anxiety, as OC users had a relation in between the established positive relation for naturally cycling women and the inverse for men (despite a similar range of factors). Findings are consistent with a growing literature showing that OC use modulates stress and anxiety-linked processes, and suggest that gendered mechanisms underlying the relation between affective complexity and anxiety may be suppressed along with ovarian hormones in OC users.

The role of neurosteroids in posttraumatic stress disorder and alcohol use disorder: A review of 10 years of clinical literature and treatment implications

Rates of alcohol use disorder (AUD) are increasing in men and women and there are high rates of concurrent posttraumatic stress disorder (PTSD) and AUD. AUD and PTSD synergistically increase symptomatology and negatively affect treatment outcomes; however, there are very limited pharmacological treatments for PTSD/AUD. Neurosteroids have been implicated in the underlying neurobiological mechanisms of both PTSD and AUD and may be a target for treatment development. This review details the past ten years of research on pregnenolone, progesterone, allopregnanolone, pregnanolone, estradiol, testosterone and dehydroepiandrosterone/dehydroepiandrosterone-sulfate (DHEA/DHEA-S) in the context of PTSD and AUD, including examination of trauma/alcohol-related variables, such as stress-reactivity. Emerging evidence that exogenous pregnenolone, progesterone, and allopregnanolone may be promising, novel interventions is also discussed. Specific emphasis is placed on examining the application of sex as a biological variable in this body of literature, given that women are more susceptible to both PTSD diagnoses and stress-related alcohol consumption.

A Perspective on Hormonal Contraception Usage in Central Nervous System Injury

Naturally occurring life stages in women are associated with changes in the milieu of endogenous ovarian hormones. Women of childbearing age may be exposed to exogenous ovarian hormone(s) because of their use of varying combinations of estrogen and progesterone hormones-containing oral contraceptives (OC; also known as "the pill"). If women have central nervous system (CNS) injury such as spinal cord injury (SCI) and traumatic brain injury (TBI) during their childbearing age, they are likely to retain their reproductive capabilities and may use OC. Many deleterious side effects of long-term OC use have been reported, such as aberrant blood clotting and endothelial dysfunction that consequently increase the risk of myocardial infarction, venous thromboembolism, and ischemic brain injury. Although controversial, studies have suggested that OC use is associated with neuropsychiatric ramifications, including uncontrollable mood swings and poorer cognitive performance. Our understanding about how the combination of endogenous hormones and OC-conferred exogenous hormones affect outcomes after CNS injuries remains limited. Therefore, understanding the impact of OC use on CNS injury outcomes needs further investigation to reveal underlying mechanisms, promote reporting in clinical or epidemiological studies, and raise awareness of possible compounded consequences. The goal of the current review is to discuss the impacts of CNS injury on endogenous ovarian hormones and vice-versa, as well as the putative consequences of exogenous ovarian hormones (OC) on the CNS to identify potential gaps in our knowledge to consider for future laboratory, epidemiological, and clinical studies.

Using unconditioned responses to predict fear acquisition, fear extinction learning, and extinction retention patterns: Sex hormone status matters

Following a traumatic event, fear dysregulation can increase the likelihood of developing post-traumatic stress disorder (PTSD). This psychopathology is twice as prevalent in women than in men. High physiological reactivity following trauma may be an early risk indicator for the development of PTSD. Elevated physiological reactivity and low estradiol levels have individually been associated with higher fear acquisition and/or lower extinction retention. Thus, sex hormone status may also modulate fear regulation abilities. However, it is unknown whether these two vulnerability factors interact to modulate fear learning and regulation. Using a fear conditioning and extinction protocol, we examined whether physiological reactivity to the aversive stimulus during fear acquisition training predicted fear responses during fear learning, extinction learning, and extinction retention. We verified whether these associations differed according to sex hormone status. Seventy-seven non-clinical participants were recruited including oral contraceptive users (n = 18), early follicular women (n = 20, [low estradiol]), mid-cycle women (n = 20, [high estradiol]), and men (n = 19). Participants underwent a three-day fear conditioning and extinction protocol (day 1: fear acquisition training; day 2: extinction training; day 3: retention test). Skin conductance responses were recorded. In early follicular women, physiological reactivity predicted conditioned and extinguished stimulus fear responses during all phases. For the remaining women, this effect was only present during fear learning and extinction learning. These findings highlight the importance of considering physiological reactivity and sex hormone status following a traumatic event. This knowledge could aid in the early identification of those at higher risk of developing PTSD.

A mouse model of oral contraceptive exposure: Depression, motivation, and the stress response

Hormonal contraceptives, including oral contraceptives (OCs), regulate hormonal cycles and broadly affect physiological processes, including stress responsivity. Whereas many users describe overall improved mood, up to 10 % of OC users experience adverse effects, including depression and anxiety. Given the link between regulation of hypothalamic-pituitary-adrenal (HPA) axis, stress exposure, and risk for depression, it is likely that OC-effects on stress mediate increased risk or increased resilience to these disorders. In this study, we developed and characterized a tractable mouse model of OC exposure with which to identify the mechanisms underlying OC modulation of brain, behavior, and mood. Specifically, we aimed to determine whether translationally relevant doses of OC-hormones in mice mimic changes in stress responsivity observed in humans taking OCs and describe behavioral changes during OC exposure. Young adult female C57Bl/6 N mice received daily ethinyl estradiol (EE) and levonorgestrel (LVNG) in 10 % sucrose, EE and drospirenone (DRSP) in 10 % sucrose, or 10 % sucrose alone. Translationally relevant doses of EE + LVNG-exposure, but not EE + DRSP, suppressed the acute stress response, consistent with effects observed in human OC users. EE + LVNG caused a specific anhedonia-like effect, without broad changes in stress-coping behavior, other depression-like behaviors, or anxiety-like behaviors. The suppression of regular estrous cycling, together with the blunting of the corticosterone response to acute stress, demonstrate the utility of this model for future studies to identify the mechanisms underlying OC interactions with stress, motivation, and risk for depression.

Estradiol reduction through aromatase inhibition impairs cocaine seeking in male rats

Introduction

Clinical and preclinical research on cocaine use disorder (CUD) has shown that sex differences in drug seeking are influenced by hormonal fluctuations. Estradiol (E2), a sex steroid hormone, has been linked to female drug effects, vulnerability to use/abuse, and psychosocial factors. Preclinical studies show that estradiol in females facilitates the extinction of cocaine-seeking behavior indicating a possible role in regulating extinction learning. Similar to females, males' brains contain the aromatase enzyme which converts testosterone to estradiol. However, it is unclear whether estradiol plays a role in male extinction learning as it does in females. Furthermore, how endogenously aromatized estradiol affects drug addiction in males is unknown. Therefore, this study investigated whether endogenous estradiol regulates cocaine seeking in male rats. We hypothesized that decreased aromatase enzyme activity, resulting in decreased estradiol synthesis in male brains, will impair extinction learning leading to increased cocaine-seeking behavior.

Methods

This hypothesis was tested using cocaine-conditioned place preference (CPP), and short access self-administration (SA), followed by extinction and reinstatement. Before each extinction session for CPP or SA, male rats received an injection of either 1 (low dose) or 2.5 mg/kg (high dose) of the aromatase inhibitor Fadrozole (FAD), or vehicle.

Results

FAD groups showed dose-dependent effects on cocaine-seeking behavior compared to the vehicle group during CPP extinction. Specifically, low dose FAD facilitated extinction of cocaine CPP, whereas high dose FAD impaired it. In contrast, neither dose of FAD had any effects on the extinction of cocaine SA. Interestingly, only the low dose FAD group had decreased active lever pressing during cue- and cocaine-primed reinstatement compared to the vehicle group. Neither dose of FAD had an effect on sucrose extinction or reinstatement of sucrose seeking.

Discussion

These results from CPP experiments suggest that estradiol may impact extinction learning, as a low dose of FAD may strengthen the formation of cocaine extinction memory. Additionally, in male rats undergoing cocaine SA, the same low dose of aromatase inhibitor effectively reduced reinstatement of cocaine-seeking behavior. Thus, estradiol impacts cocaine seeking and extinction in both males and females, and it may also influence the development of sex-specific treatment strategies for CUD.

Targeting Human Glucocorticoid Receptors in Fear Learning: A Multiscale Integrated Approach to Study Functional Connectivity

Fear extinction is a phenomenon that involves a gradual reduction in conditioned fear responses through repeated exposure to fear-inducing cues. Functional brain connectivity assessments, such as functional magnetic resonance imaging (fMRI), provide valuable insights into how brain regions communicate during these processes. Stress, a ubiquitous aspect of life, influences fear learning and extinction by changing the activity of the amygdala, prefrontal cortex, and hippocampus, leading to enhanced fear responses and/or impaired extinction. Glucocorticoid receptors (GRs) are key to the stress response and show a dual function in fear regulation: while they enhance the consolidation of fear memories, they also facilitate extinction. Accordingly, GR dysregulation is associated with anxiety and mood disorders. Recent advancements in cognitive neuroscience underscore the need for a comprehensive understanding that integrates perspectives from the molecular, cellular, and systems levels. In particular, neuropharmacology provides valuable insights into neurotransmitter and receptor systems, aiding the investigation of mechanisms underlying fear regulation and potential therapeutic targets. A notable player in this context is cortisol, a key stress hormone, which significantly influences both fear memory reconsolidation and extinction processes. Gaining a thorough understanding of these intricate interactions has implications in terms of addressing psychiatric disorders related to stress. This review sheds light on the complex interactions between cognitive processes, emotions, and their neural bases. In this endeavor, our aim is to reshape the comprehension of fear, stress, and their implications for emotional well-being, ultimately aiding in the development of therapeutic interventions.

The role of sex hormones, oral contraceptive use, and its parameters on visuospatial abilities, verbal fluency, and verbal memory

Sex hormones can cross the blood-brain barrier and access brain regions underlying higher-order cognition. Containing synthetic sex hormones, oral contraceptives (OC) have been found to modulate visuospatial and verbal abilities, though inconsistencies have been found in the literature. Among possible explanations, certain OC use parameters (progestin androgenicity, synthetic hormone levels, duration of use) have not received consistent consideration. Thus, the objectives were to (1) examine group differences between men, combined OC users, and naturally cycling women (NC women; not using OC) in visuospatial abilities, verbal fluency, and verbal memory and (2) investigate the contribution of endogenous and exogenous sex hormones on these effects. We also aimed to (3) identify OC use parameters relevant to cognitive outcomes. In total, 70 combined OC users, 53 early follicular (EF) women, 43 pre-ovulatory (PO) women, and 47 men underwent cognitive tests. Performance was compared based on hormonal milieus (OC, EF, PO, men) and OC users' contraceptive androgenicity (anti, low, high). Correlations between performance, hormone levels and OC use duration were also conducted. OC use dampened the sex difference that typically favors men in 3D visuospatial abilities, whereas its duration of use positively predicted verbal fluency. Androgenicity and hormone levels did not predict performance in any task. These results highlight the importance of considering OC use duration. Results also did not support a role for androgenicity in cognition. Importantly, combined OC use (including prolonged use) does not impair visuospatial, verbal, and memory functions in a healthy young sample.

Effects of oral contraceptives on intrusive memories: a secondary analysis of two studies using the trauma film paradigm in healthy women

Background: Women are more likely to develop post-traumatic stress disorder (PTSD) than men. Recent research suggests an impact of oral contraceptive (OC) intake on PTSD and intrusive memories, a hallmark symptom of PTSD. Although a majority of women use OCs at some point in their lives, the effects on PTSD pathogenesis are only poorly understood.Objective: In the current paper, we aimed to investigate the impact of OC intake on the acquisition and consolidation of intrusive memories in healthy women after watching a trauma film paradigm.Methods: We performed a secondary analysis of a pooled dataset (N = 437) of two previously conducted and published studies investigating the effect of oxytocin on the development of intrusive memories.Results: Women taking OCs showed an attenuated decline of intrusive memories over time after having watched the trauma film compared to naturally cycling women (F(2.75, 1167) = 3.79, p = .03, η p 2  = .01).Conclusion: These findings indicate that the intake of OCs is associated with the development of intrusive memories after a trauma film paradigm. This indication emphasizes the need to further investigate the complex impact of OCs and gonadal hormones on fear learning processes and PTSD.

Dissociable role of the basolateral complex of the amygdala in the acquisition and extinction of conditioned fear following reproductive experience in female rats

In female rats and humans, reproductive experience (i.e., pregnancy) alters the behavioral, hormonal and molecular substrates of fear extinction. Here, we assessed whether the role of a central neural substrate of fear extinction, the basolateral amygdala (BLA), also changes following reproductive experience. Nulliparous (virgin) and primiparous (one prior pregnancy) female rats received infusions of the GABAA agonist, muscimol, to temporarily inactivate the BLA prior to fear conditioning or extinction training. In follow up experiments, the BLA was also inactivated immediately after extinction training. BLA inactivation impaired the acquisition and expression of conditioned fear in both nulliparous and primiparous rats. In nulliparous rats, BLA inactivation prior to or immediately after extinction training impaired extinction retention. In contrast, in primiparous rats, BLA inactivation prior to or immediately after extinction training did not impair extinction retention, despite suppressing freezing during extinction training. These results suggest that, consistent with past findings in males, the BLA is a central component of the neural circuitry of fear acquisition and its extinction in virgin female rats. However, after pregnancy, female rats no longer depend on the BLA to extinguish fear, despite requiring the BLA to acquire conditioned fear. Given that fear extinction forms the basis of exposure therapy for anxiety disorders in humans, the present findings may have clinical implications. To improve the efficacy of exposure therapy for anxiety disorders, we may need to target different mechanisms in females dependent on their reproductive history.

Evidence that ovarian hormones, but not diet and exercise, contribute to the sex disparity in post-traumatic stress disorder

Females are twice as likely as males to receive a diagnosis of post-traumatic stress disorder (PTSD). One hypothesis for this sex disparity is that ovarian hormones, including estrogen and progesterone, contribute to PTSD risk. Alternatively, sex differences in lifestyle factors, such as diet and exercise, may play a role in PTSD risk. Using data from the Atlantic Partnership for Tomorrow's Health (PATH) cohort (n = 16,899), the relationship between endogenous hormone fluctuations (e.g., menarche, pregnancy, and menopause), exogenous hormone use (e.g., hormonal contraception and hormone replacement therapy (HRT)) and lifestyle variables (diet and exercise habits, as measured by the Mediterranean Diet Adherence Screener, Healthy Eating Index, and International Physical Activity Questionnaire) with PTSD diagnosis and treatment were analyzed. While several hormonal variables, including contraceptive use, higher total number of pregnancies, younger menarche age, and having undergone menopause increased the risk of PTSD, no lifestyle variables contributed to an increased risk of PTSD diagnosis. These findings support the theory that ovarian hormones contribute to the sex-linked disparity in PTSD diagnosis.

Morphologic alterations of the fear circuitry: the role of sex hormones and oral contraceptives

Background

Endogenous sex hormones and oral contraceptives (OCs) have been shown to influence key regions implicated in fear processing. While OC use has been found to impact brain morphology, methodological challenges remain to be addressed, such as avoiding selection bias between OC users and non-users, as well as examining potential lasting effects of OC intake.

Objective

We investigated the current and lasting effects of OC use, as well as the interplay between the current hormonal milieu and history of hormonal contraception use on structural correlates of the fear circuitry. We also examined the role of endogenous and exogenous sex hormones within this network.

Methods

We recruited healthy adults aged 23-35 who identified as women currently using (n = 62) or having used (n = 37) solely combined OCs, women who never used any hormonal contraceptives (n = 40), or men (n = 41). Salivary endogenous sex hormones and current users' salivary ethinyl estradiol (EE) were assessed using liquid chromatography - tandem mass spectrometry. Using structural magnetic resonance imaging, we extracted surface-based gray matter volumes (GMVs) and cortical thickness (CT) for regions of interest of the fear circuitry. Exploratory whole-brain analyses were conducted with surface-based and voxel-based morphometry methods.

Results

Compared to men, all three groups of women exhibited a larger GMV of the dorsal anterior cingulate cortex, while only current users showed a thinner ventromedial prefrontal cortex. Irrespective of the menstrual cycle phase, never users exhibited a thicker right anterior insular cortex than past users. While associations with endogenous sex hormones remain unclear, we showed that EE dosage in current users had a greater influence on brain anatomy compared to salivary EE levels and progestin androgenicity, with lower doses being associated with smaller cortical GMVs.

Discussion

Our results highlight a sex difference for the dorsal anterior cingulate cortex GMV (a fear-promoting region), as well as a reduced CT of the ventromedial prefrontal cortex (a fear-inhibiting region) specific to current OC use. Precisely, this finding was driven by lower EE doses. These findings may represent structural vulnerabilities to anxiety and stress-related disorders. We showed little evidence of durable anatomical effects, suggesting that OC intake can (reversibly) affect fear-related brain morphology.

Sex differences in avoidance behavior and cued threat memory dynamics in mice: Interactions between estrous cycle and genetic background

Anxiety disorders are the most prevalent mental illnesses worldwide, exhibit high heritability, and affect twice as many women as men. To evaluate potential interactions between genetic background and cycling ovarian hormones on sex differences in susceptibility to negative valence behaviors relevant to anxiety disorders, we assayed avoidance behavior and cued threat memory dynamics in gonadally-intact adult male and female mice across four common inbred mouse strains: C57Bl/6J, 129S1/SVlmJ, DBA/2J, and BALB/cJ. Independent of sex, C57Bl/6J mice exhibited low avoidance but high threat memory, 129S1/SvlmJ mice high avoidance and high threat memory, DBA/2J mice low avoidance and low threat memory, and BALB/cJ mice high avoidance but low threat memory. Within-strain comparisons revealed reduced avoidance behavior in the high hormone phase of the estrous cycle (proestrus) compared to all other estrous phases in all strains except DBA/2J, which did not exhibit cycle-dependent behavioral fluctuations. Robust and opposing sex differences in threat conditioning and extinction training were found in the C57Bl/6J and 129S1/SvlmJ lines, whereas no sex differences were observed in the DBA/2J or BALB/cJ lines. C57Bl/6J males exhibited enhanced acute threat memory, whereas 129S1/SvlmJ females exhibited enhanced sustained threat memory, compared to their sex-matched littermates. These effects were not mediated by estrous cycle stage or sex differences in active versus passive defensive behavioral responses. Our data demonstrate that core features of behavioral endophenotypes relevant to anxiety disorders, such as avoidance and threat memory, are genetically driven yet dissociable and can be influenced further by cycling ovarian hormones.

Developmental changes in functional connectivity between the prefrontal cortex and amygdala following fear extinction

The amygdala and prefrontal cortex (PFC) undergo dramatic changes in structure, function, and regional connectivity in early life, ultimately stabilizing in early adulthood. Pathways between these two structures underlie many forms of emotional learning, including the extinction of conditioned fear. Here we sought to characterize changes in extinction-related medial PFC (mPFC) → amygdala functional connectivity across development that might explain adolescent impairments in extinction. The retrograde tracer Fluorogold was infused into the amygdala of postnatal day (P)22-23 (juvenile), P31-32 (adolescent), or ≥ P69 (adult) rats, which were then exposed to fear conditioning and extinction training. Brains were collected following extinction or context exposure and processed for expression of pMAPK (as a marker of learning-dependent plasticity) in prelimbic (PL) and infralimbic (IL) amygdala-projecting neurons. Consistent with previous findings, amygdala-projecting mPFC neurons were located primarily in layers (L)II/III and V of the mPFC. We noted that mPFC LII/III projected predominantly to the ipsilateral basolateral amygdala, whereas LV projected bilaterally and targeted multiple amygdalar nuclei. Extinction was not associated with changes in extinction-related plasticity in the PL-amygdala pathways in any age group. No changes were seen in LII/III of the IL, but extinction-related plasticity in LV amygdala-projecting IL neurons decreased linearly across development. These findings suggest that extinction-related functional connectivity between the IL and the amygdala undergoes fundamental changes across development that may contribute to alterations in fear suppression across development.

Weight Suppression and Risk for Childhood Psychiatric Disorders

Weight suppression, defined as the discrepancy between an individual's highest historical weight and their current weight, has been implicated in the development and maintenance of eating disorders. Although weight suppression has also been found to impact mood, anxiety and suicidal behavior in patients with and without disordered eating, it has not been examined as a transdiagnostic risk factor for general psychopathology. The current study examined growth records of 281 children and adolescents (ages 7 to 17) newly diagnosed with psychiatric disorders to determine whether these children were more likely to be weight suppressed as compared to an age- and gender-matched control group. Findings suggest that weight suppression is related to an increased risk for anxiety disorders and externalizing disorders for males. These results underscore the need for psychiatric and behavioral health providers to review pediatric growth charts as a routine part of psychiatric evaluation. As weight restoration is a necessary precondition for eating disorder recovery, more research is necessary to determine if weight restoration can enhance treatments for psychiatric symptoms occurring in the context of weight suppression.

Inhibition of Estradiol Signaling in the Basolateral Amygdala Impairs Extinction Memory Recall for Heroin-Conditioned Cues in a Sex-Specific Manner

INTRODUCTION

Relapse is a major treatment barrier for opioid use disorder. Environmental cues become associated with the rewarding effects of opioids and can precipitate relapse, even after numerous unreinforced cue presentations, due to deficits in extinction memory recall (EMR). Estradiol (E2) modulates EMR of fear-related cues, but it is unknown whether E2 impacts EMR of reward cues and what brain region(s) are responsible for E2s effects. Here, we hypothesize that inhibition of E2 signaling in the basolateral amygdala (BLA) will impair EMR of a heroin-associated cue in both male and female rats.

METHODS

We pharmacologically manipulated E2 signaling to characterize the role of E2 in the BLA on heroin-cue EMR. Following heroin self-administration, during which a light/tone cue was co-presented with each heroin infusion, rats underwent cued extinction to extinguish the conditioned association between the light/tone and heroin. During extinction, E2 signaling in the BLA was blocked by an aromatase inhibitor or specific estrogen receptor (ER) antagonists. The next day, subjects underwent a cued test to assess heroin-cue EMR.

RESULTS

In both experiments, females took more heroin than males (mg/kg) and had higher operant responding during cued extinction. Inhibition of E2 synthesis in the BLA impaired heroin-cue EMR in both sexes. Notably, E2s actions are mediated by different ER mechanisms, ERα in males but ERβ in females.

CONCLUSIONS

This study is the first to demonstrate a behavioral role for centrally-produced E2 in the BLA and that E2 also impacts EMR of reward-associated stimuli in both sexes.

Association between perimenopausal age and greater posttraumatic stress disorder and depression symptoms in trauma-exposed women

OBJECTIVE

This study aimed to determine the relationship between stages of the menopause transition (premenopausal, perimenopausal, and postmenopausal) on symptoms of posttraumatic stress disorder (PTSD) and depression in trauma-exposed women.

METHODS

A cross-sectional study conducted between 2005 and 2017 recruited and enrolled an urban community sample (n = 6,093) from nonpsychiatric medical clinic waiting rooms of Grady Memorial Hospital, a public safety net hospital in Atlanta, Georgia. Participants were female, 18 to 65 years old, and predominantly Black/African American.

RESULTS

Of the 6,093 participants, 93.8% were Black/African American, 2.5% were White, and 3.8% were of all other races (Hispanic/Latino, Asian, multiracial). Participants younger than 40 years were categorized as premenopausal (n = 3,166), between 40 and 55 years of age were categorized as perimenopausal (n = 2,127), and older than 55 years were categorized as postmenopausal (n = 790). Menopause status was associated with total PTSD symptom severity ( F2,5416 = 9.61, P < 0.001), symptom severity within all three PTSD symptom clusters (avoidance/numbing symptoms: F2,5416 = 7.10, P < 0.001; intrusive symptoms: F2,5416 = 7.04, P < 0.001; hyperarousal symptoms: F2,5409 = 8.31, P < 0.001), and depression symptom severity ( F2,5148 = 11.4, P < 0.001). Compared with both premenopausal and postmenopausal women, perimenopausal women reported significantly worse total PTSD symptoms, symptoms in the hyperarousal cluster, and depressive symptoms.

CONCLUSIONS

The current cross-sectional data show that symptoms of PTSD and depression in women are associated with reproductive age, such that perimenopausal women show higher symptom severity than premenopausal and postmenopausal women. Future longitudinal studies can reveal how changes in hormones over the course of the menopause transition impact the symptoms, neurobiology, and psychophysiology of PTSD.

Inactivation of medial or lateral orbitofrontal cortex during fear extinction did not interfere with fear renewal

Hyperactive orbitofrontal cortical activation is commonly seen in patients of obsessive-compulsive disorder (OCD). Previous studies from our laboratory showed that for rats with aberrant activation of the orbitofrontal cortex (OFC) during the extinction phase, they were unable to use contexts as the reference for proper retrieval of fear memory during renewal test. This result supported the phenomenon that many OCD patients show poor regulation of fear-related behavior. Since there are robust anatomical connections of the OFC with the fear-circuit, we aim to further examine whether the OFC is actively engaged in fear regulation under normal circumstances. In this study, the lateral or medial OFC was inactivated during the extinction phase using the ABA fear renewal procedure. We found that these animals showed intact fear renewal during retrieval test with their freezing levels equivalent to the control rats, revealing that the OFC did not have decisive roles in extinction acquisition. Together with our previous study, we suggest that the OFC only interferes with fear regulation when it becomes pathophysiologically hyperactive.

Protocol for a randomized controlled study examining the role of rapid eye movement sleep in fear-related mechanisms: rapid eye movement fragmentation and fear inhibition in adults with insomnia disorders before and after cognitive behavioral therapy for insomnia

Insomnia confers a 2.5-to-3-fold risk of developing posttraumatic stress disorder (PTSD) after a traumatic event. The mechanism underlying this increased risk, however, remains unknown. We postulate insomnia may contribute to PTSD by disrupting rapid eye movement (REM) sleep, as REM sleep disruption has been shown to impair fear inhibitory processes, which are central to the natural recovery from trauma. To test this hypothesis, the following protocol aims to: (1) examine the relationship between REM sleep and fear inhibition in insomnia, and (2) examine whether reducing REM fragmentation by treating insomnia, in turn, improves fear inhibition. Ninety-two adults with Insomnia Disorder will be block randomized (1:1; stratified by sex) to an active treatment (7 weekly sessions of Cognitive Behavioral Therapy for Insomnia (CBT-I) via telehealth) or waitlist control condition. REM sleep (latent variable derived from REM %, REM efficiency, and REM latency) and fear inhibition (i.e. safety signal and extinction recall) will be assessed pre- and post-treatment in a 4 night/3 day testing protocol via at-home polysomnography and the fear-potentiated startle paradigm, respectively. Fear extinction recall will serve as the primary outcome, while safety signal recall will serve as the secondary outcome. In summary, this study aims to test an underlying mechanism potentially explaining why insomnia greatly increases PTSD risk, while demonstrating an existing clinical intervention (CBT-I) can be used to improve this mechanism. Findings will have potential clinical implications for novel approaches in the prevention, early intervention, and treatment of PTSD.

Estrous cycle state-dependent renewal of appetitive behavior recruits unique patterns of Arc mRNA in female rats

Introduction

Renewal is a behavioral phenomenon wherein extinction learning fails to generalize between different contextual environments, thereby representing a significant challenge to extinction-based rehabilitative therapies. Previously, we have shown that renewal of extinguished appetitive behavior differs across the estrous cycle of the female rat. In this experiment that effect is replicated and extended upon to understand how the estrous cycle may modulate contextual representation at the neuronal population level to drive renewal.

Methods

Estrous cycle stage [i.e., proestrus (P, high hormone) or metestrus/diestrus (M/D, low hormone)] was considered during two important learning and behavioral expression windows: at extinction training and during long-term memory (LTM)/renewal testing. Cellular compartment analysis of temporal activity using fluorescence in situ hybridization (catFISH) for Arc mRNA was conducted after the distinct context-stimulus exposures.

Results

Rats in P during context-dependent extinction training but in a different stage of the estrous cycle during LTM and renewal testing (P-different) were shown to exhibit more renewal of conditioned foodcup (but not conditioned orienting) behavior compared to rats in other estrous cycle groups. Importantly, we discovered this depends on the order of tests. P-different rats showed differential Arc mRNA expression in regions of the prefrontal cortex (PFC), amygdala, and hippocampus (HPC). For each case P-different rats had more co-expression (i.e., expression of both nuclear and cytoplasmic) of Arc mRNA compared to other groups; specific to the dorsal HPC, P-different rats also had a more robust Arc mRNA response to the extinction context exposure.

Conclusion

These data suggest female rats show estrous cycle state-dependent renewal of appetitive behavior, and differences in context and conditioned stimulus representation at the neuronal level may drive this effect.

Triple network model of brain connectivity changes related to adverse mood effects in an oral contraceptive placebo-controlled trial

Combined oral contraceptives (COC) are among the most commonly used contraceptive methods worldwide, and mood side effects are the major reason for discontinuation of treatment. We here investigate the directed connectivity patterns associated with the mood side effects of an androgenic COC in a double-blind randomized, placebo-controlled trial in women with a history of affective COC side effects (n = 34). We used spectral dynamic causal modeling on a triple network model consisting of the default mode network (DMN), salience network (SN) and executive control network (ECN). Within this framework, we assessed the treatment-related changes in directed connectivity associated with adverse mood side effects. Overall, during COC use, we found a pattern of enhanced connectivity within the DMN and decreased connectivity within the ECN. The dorsal anterior cingulate cortex (SN) mediates an increased recruitment of the DMN by the ECN during treatment. Mood lability was the most prominent COC-induced symptom and also arose as the side effect most consistently related to connectivity changes. Connections that were related to increased mood lability showed increased connectivity during COC treatment, while connections that were related to decreased mood lability showed decreased connectivity during COC treatment. Among these, the connections with the highest effect size could also predict the participants' treatment group above chance.

Neural correlates of immediate versus delayed extinction when simultaneously varying the time of the test in humans

Anxiety disorders are effectively treated with exposure therapy based on the extinction of Pavlovian fear conditioning. Animal research indicates that both the timing of extinction and test are important factors to reduce the return of fear. However, empirical evidence in humans is incomplete and inconsistent. In this neuroimaging study, we, therefore, tested 103 young, healthy participants in a 2-factorial between-subjects design with the factors extinction group (immediate, delayed) and test group (+1 day and +7 days). Immediate extinction led to greater retention of fear memory at the beginning of extinction training indicated by increased skin conductance responses. A return of fear was observed in both extinction groups, with a trend toward a greater return of fear in immediate extinction. The return of fear was generally higher in groups with an early test. Neuroimaging results show successful cross-group fear acquisition and retention, as well as activation of the left nucleus accumbens during extinction training. Importantly, the delayed extinction group showed a larger bilateral nucleus accumbens activation during test. This nucleus accumbens finding is discussed in terms of salience, contingency, relief, and prediction error processing. It may imply that the delayed extinction group benefits more from the test as a new learning opportunity.

Hormonal contraception and cognition: Considering the influence of endogenous ovarian hormones and genes for clinical translation

Despite the well-known influence of ovarian hormones on the brain and widespread use of hormonal contraception (HC) since the 1960s, our knowledge of HC's cognitive effects remains limited. To date, the cognitive findings have been inconsistent. In order to establish what might make HC studies more consistent, we surveyed the literature on HCs and cognition to determine whether studies considered HC formulation, phase, pharmacokinetics, duration, and gene interactions, and assessed whether oversight of these factors might contribute to variable findings. We found that synthetic HC hormones exert dose-dependent effects, the day of oral contraceptive (Pill) ingestion is critical for understanding cognitive changes, and gene-cognition relationships differ in women taking the Pill likely due to suppressed endogenous hormones. When these factors were overlooked, results were not consistent. We close with recommendations for research more likely to yield consistent findings and be therefore, translatable.

Estradiol-mediated protection against high-fat diet induced anxiety and obesity is associated with changes in the gut microbiota in female mice

Decreased estrogens during menopause are associated with increased risk of anxiety, depression, type 2 diabetes and obesity. Similarly, depleting estrogens in rodents by ovariectomy, combined with a high-fat diet (HFD), increases anxiety and adiposity. How estrogens and diet interact to affect anxiety and metabolism is poorly understood. Mounting evidence indicates that gut microbiota influence anxiety and metabolism. Here, we investigated the effects of estradiol (E) and HFD on anxiety, metabolism, and their correlation with changes in gut microbiota in female mice. Adult C57BL/6J mice were ovariectomized, implanted with E or vehicle-containing capsules and fed a standard diet or HFD. Anxiety-like behavior was assessed and neuronal activation was measured by c-fos immunoreactivity throughout the brain using iDISCO. HFD increased anxiety-like behavior, while E reduced this HFD-dependent anxiogenic effect. Interestingly, E decreased neuronal activation in brain regions involved in anxiety and metabolism. E treatment also altered gut microbes, a subset of which were associated with anxiety-like behavior. These findings provide insight into gut microbiota-based therapies for anxiety and metabolic disorders associated with declining estrogens in menopausal women.

Do oral contraceptives modulate the effects of stress induction on one-session exposure efficacy and generalization in women?

RATIONALE

The administration of glucocorticoids (GC) as an adjunct to exposure represents a promising strategy to improve one-session exposure outcome in anxiety disorders. It remains to be determined whether similar effects can be induced with the use of acute stress. Furthermore, the possible modulation of exposure effects by hormonal factors (e.g., use of oral contraceptives (OCs)) was not explored so far.

OBJECTIVES

We investigated whether acute stress prior to one-session exposure for spider fear affects its efficacy in women using oral contraceptives (OC) relative to free-cycling (FC) women. In addition, effects of stress on generalization of exposure therapy effects towards untreated stimuli were examined.

METHODS

Women with fears of spiders and cockroaches were randomly assigned to a Stress (n = 24) or No-Stress (n = 24) condition prior to one-session exposure. Of these 48 participants, 19 women used OC (n = 9 in the Stress, and n = 10 in the No-Stress group). All FC women had a regular menstrual cycle and were tested only in the follicular phase of their menstrual cycle. Pre-exposure stress induction was realized with the socially evaluated cold-pressor test. Exposure-induced changes towards treated and untreated fear stimuli were tested with behavioral approach tests for spiders and cockroaches and subjective fear and self-report measures.

RESULTS

Acute stress did not influence exposure-induced reduction in fear and avoidance of the treated stimuli (spiders). Similarly, stress had no effect on the generalization of exposure-therapy effects towards untreated stimuli (cockroaches). Exposure-induced reduction in subjective fear and self-report measures for treated stimuli was less evident in women using OC specifically after pre-exposure stress. Women using OC had higher levels of subjective fear and scored higher in self-report measures at post-treatment (24 h after exposure) and follow-up (4 weeks after exposure).

CONCLUSIONS

OC intake may represent an important confounding factor in augmentation studies using stress or GC.

The role of estrogen receptor manipulation during traumatic stress on changes in emotional memory induced by traumatic stress

RATIONALE

Traumatic stress leads to persistent fear, which is a core feature of post-traumatic stress disorder (PTSD). Women are more likely than men to develop PTSD after trauma exposure, which suggests women are differentially sensitive to traumatic stress. However, it is unclear how this differential sensitivity manifests. Cyclical changes in vascular estrogen release could be a contributing factor where levels of vascular estrogens (and activation of estrogen receptors) at the time of traumatic stress alter the impact of traumatic stress.

METHODS

To examine this, we manipulated estrogen receptors at the time of stress and observed the effect this had on fear and extinction memory (within the single prolonged stress (SPS) paradigm) in female rats. In all experiments, freezing and darting were used to measure fear and extinction memory.

RESULTS

In Experiment 1, SPS enhanced freezing during extinction testing, and this effect was blocked by nuclear estrogen receptor antagonism prior to SPS. In Experiment 2, SPS decreased conditioned freezing during the acquisition and testing of extinction. Administration of 17β-estradiol altered freezing in control and SPS animals during the acquisition of extinction, but this treatment had no effect on freezing during the testing of extinction memory. In all experiments, darting was only observed to footshock onset during fear conditioning.

CONCLUSION

The results suggest multiple behaviors (or different behavioral paradigms) are needed to characterize the nature of traumatic stress effects on emotional memory in female rats and that nuclear estrogen receptor antagonism prior to SPS blocks SPS effects on emotional memory in female rats.

The impact of between-session habituation, within-session habituation, and weight gain on response to food exposure for adolescents with eating disorders

OBJECTIVE

Exposure therapy is a promising treatment for eating disorders (EDs). However, questions remain about the effectiveness of exposure to feared foods during the weight restoration phase of treatment, and the importance of between-session and within-session habituation.

METHOD

We recruited 54 adolescents from a partial hospitalization program (PHP) for EDs which included daily food exposure. Throughout treatment, participants provided subjective units of distress (SUDS) ratings before and after eating a feared food, and completed measures of ED symptomatology.

RESULTS

Multilevel models found that pre-exposure SUDS decreased over time, providing some evidence that between-session habituation occurred. In contrast, the difference between pre-exposure and post-exposure SUDS did not decrease over time, indicating that within-session habituation did not occur. Weight gain predicted greater between-session habituation to feared foods, but did not predict within-session habituation. Between-session habituation, but not within-session habituation, predicted favorable treatment outcomes, including weight gain and improvements on the Children's Eating Attitudes Test and Fear of Food Measure.

DISCUSSION

Partial hospitalization programs that include daily exposure to feared foods may be effective at decreasing anxiety about foods for adolescents with EDs who are experiencing weight restoration. Further research is warranted to replicate our findings challenging the importance of within-session habituation, and to better understand between-session habituation and inhibitory learning as mechanisms of change when conducting food exposure for EDs.

PUBLIC SIGNIFICANCE

This study provides some evidence that PHPs that include food exposure may be useful for adolescents with EDs who are experiencing weight restoration. Between-session habituation, but not within-session habituation, predicted favorable treatment outcomes. Further research is needed to determine whether clinicians can disregard within-session habituation when conducting food exposure for EDs, and understand the importance of between-session habituation as a potential mechanism of food exposure.

Progesterone and contraceptive progestin actions on the brain: A systematic review of animal studies and comparison to human neuroimaging studies

In this review we systematically summarize the effects of progesterone and synthetic progestins on neurogenesis, synaptogenesis, myelination and six neurotransmitter systems. Several parallels between progesterone and older generation progestin actions emerged, suggesting actions via progesterone receptors. However, existing results suggest a general lack of knowledge regarding the effects of currently used progestins in hormonal contraception regarding these cellular and molecular brain parameters. Human neuroimaging studies were reviewed with a focus on randomized placebo-controlled trials and cross-sectional studies controlling for progestin type. The prefrontal cortex, amygdala, salience network and hippocampus were identified as regions of interest for future preclinical studies. This review proposes a series of experiments to elucidate the cellular and molecular actions of contraceptive progestins in these areas and link these actions to behavioral markers of emotional and cognitive functioning. Emotional effects of contraceptive progestins appear to be related to 1) alterations in the serotonergic system, 2) direct/indirect modulations of inhibitory GABA-ergic signalling via effects on the allopregnanolone content of the brain, which differ between androgenic and anti-androgenic progestins. Cognitive effects of combined oral contraceptives appear to depend on the ethinylestradiol dose.

Is Fear Extinction Impairment Central to Psychopathology?

As discussed in this chapter, there have been enormous advances in our understanding of how anxiety disorders develop, are maintained, and can be treated. Many of these advances have been the result of translational studies using fear conditioning and extinction models. Despite these successes, we recognize, as a field, that there are important limitations in the extent to which extinction can explain how anxiety disorders and behaviors remit. Clinically speaking, the outstanding challenge for treatment of anxiety disorders is to improve the current suboptimal success rates. Over the past 30 years, we have not improved our treatment success rates despite employing many pharmacological and pharmacological strategies. While extinction and related fear circuitry mechanisms most certainly appear to play a role in treatment of anxiety disorders, they are also apparently insufficient to fully accommodate the varied responses individuals exhibit with this treatment approach. Increasingly diverse and innovative approaches are needed that accommodate the multitude of change mechanisms involved in treating anxiety. However, this is not to suggest ignoring the key role that extinction and memory updating processes play in overcoming anxiety.

Sex Differences in Depression and Anxiety

Depression and anxiety disorders carry a tremendous worldwide burden and emerge as a significant cause of disability among western societies. Both disorders are known to disproportionally affect women, as they are twice more likely to be diagnosed and moreover, they are also prone to suffer from female-specific mood disorders. Importantly, the prevalence of these affective disorders has notably risen after the COVID pandemic, especially in women. In this chapter, we describe factors that are possibly contributing to the expression of such sex differences in depression and anxiety. For this, we overview the effect of transcriptomic and genetic factors, the immune system, neuroendocrine aspects, and cognition. Furthermore, we also provide evidence of sex differences in antidepressant response and their causes. Finally, we emphasize the importance to consider sex as a biological variable in preclinical and clinical research, which may facilitate the discovery and development of new and more efficacious antidepressant and anxiolytic pharmacotherapies for both women and men.

The cerebellum and fear extinction: evidence from rodent and human studies

The role of the cerebellum in emotional control has gained increasing interest, with studies showing it is involved in fear learning and memory in both humans and rodents. This review will focus on the contributions of the cerebellum to the extinction of learned fear responses. Extinction of fearful memories is critical for adaptive behaviour, and is clinically relevant to anxiety disorders such as post-traumatic stress disorder, in which deficits in extinction processes are thought to occur. We present evidence that supports cerebellar involvement in fear extinction, from rodent studies that investigate molecular mechanisms and functional connectivity with other brain regions of the known fear extinction network, to fMRI studies in humans. This evidence is considered in relation to the theoretical framework that the cerebellum is involved in the formation and updating of internal models of the inner and outer world by detecting errors between predicted and actual outcomes. In the case of fear conditioning, these internal models are thought to predict the occurrence of an aversive unconditioned stimulus (US), and when the aversive US is unexpectedly omitted during extinction learning the cerebellum uses prediction errors to update the internal model. Differences between human and rodent studies are highlighted to help inform future work.

The Impacts of Sex Differences and Sex Hormones on Fear Extinction

Fear extinction memories are strongly modulated by sex and hormonal status, but the exact mechanisms are still being discovered. In humans, there are some basal and task-related features in which male and female individuals differ in fear conditioning paradigms. However, analyses considering the effects of sex hormones demonstrate a role for estradiol in fear extinction memory consolidation. Translational studies are taking advantage of the convergent findings between species to understand the brain structures implicated. Nevertheless, the human brain is complex and the transfer of these findings into the clinics remains a challenge. The promising advances in the field together with the standardization of fear extinction methodologies in humans will benefit the design of new personalized therapies.

Sex differences in fear responses: Neural circuits

Women have increased vulnerability to PTSD and anxiety disorders compared to men. Understanding the neurobiological underpinnings of these disorders is critical for identifying risk factors and developing appropriate sex-specific interventions. Despite the clear clinical relevance of an examination of sex differences in fear responses, the vast majority of pre-clinical research on fear learning and memory formation has exclusively used male animals. This review highlights sex differences in context and cued fear conditioning, fear extinction and fear generalization with a focus on the neural circuits underlying these behaviors in rodents. There are mixed reports of behavioral sex differences in context and cued fear conditioning paradigms, which can depend upon the behavioral indices of fear. However, there is greater evidence of differential activation of the hippocampus, amygdalar nuclei and the prefrontal cortical regions in male and female rodents during context and cued fear conditioning. The bed nucleus of the stria terminalis (BNST), a sexually dimorphic structure, is of particular interest as it differentially contributes to fear responses in males and females. In addition, while the influence of the estrous cycle on different phases of fear conditioning is delineated, the clearest modulatory effect of estrogen is on fear extinction processes. Examining the variability in neural responses and behavior in both sexes should increase our understanding of how that variability contributes to the neurobiology of affective disorders. This article is part of the Special Issue on 'Fear, anxiety and PTSD'.

How Different Factors in Combination Change Fear Extinction Learning: The Case of Sex and Stress Hormones

Effects of a specific factor on fear extinction or exposure therapy have revealed promising results, for example how sex or stress hormones exert the capability to critically change extinction learning and consolidation processes. However, we must acknowledge that in real life these factors do not operate in isolation, they go hand in hand. In this chapter, the available evidence regarding interactions of sex and stress hormones on extinction processes and exposure therapy will be integrated and discussed. First hints exist that these factors in combination critically target extinction learning and consolidation processes, calling for more detailed research on the exact underlying mechanisms. In addition to experiments with high sample sizes, we must aim for a collaborative effort of laboratories across the whole world to be able to identify critical combinations of factors associated with improved, but also impaired extinction processes and exposure therapy success. We expect that the revelation of further relevant factors will not only be limited to the interplay between sex and stress hormones but will include factors such as sleep and exercise as well. In the long run, uncovering the most important interaction effects will give us critical hints for differential treatment options to be realized in the sense of a personalized medicine approach.

Involvement of D2-like dopaminergic receptors in contextual fear conditioning in female rats: influence of estrous cycle

Introduction: Dopamine has been increasingly recognized as a key neurotransmitter regulating fear/anxiety states. Nevertheless, the influence of sex and estrous cycle differences on the role of dopamine in fear responses needs further investigation. We aimed to evaluate the effects of sulpiride (a dopaminergic D2-like receptor antagonist) on contextual fear conditioning in females while exploring the influence of the estrous cycle. Methods: First, using a contextual fear conditioning paradigm, we assessed potential differences in acquisition, expression, and extinction of the conditioned freezing response in male and female (split in proestrus/estrus and metestrus/diestrus) Wistar rats. In a second cohort, we evaluated the effects of sulpiride (20 and 40 mg/kg) on contextual conditioned fear in females during proestrus/estrus and metestrus/diestrus. Potential nonspecific effects were assessed in motor activity assays (catalepsy and open-field tests). Results: No sex differences nor estrous cycle effects on freezing behavior were observed during the fear conditioning phases. Sulpiride reduced freezing expression in female rats. Moreover, females during the proestrus/estrus phases of the estrous cycle were more sensitive to the effects of sulpiride than females in metestrus/diestrus. Sulpiride did not cause motor impairments. Discussion: Although no sex or estrous cycle differences were observed in basal conditioned fear expression and extinction, the estrous cycle seems to influence the effects of D2-like antagonists on contextual fear conditioning.

Imaging the human brain on oral contraceptives: A review of structural imaging methods and implications for future research goals

Worldwide over 150 million women use oral contraceptives (OCs), which are the most prescribed form of contraception in both the United States and in European countries. Sex hormones, such as estradiol and progesterone, are important endogenous hormones known for shaping the brain across the life span. Synthetic hormones, which are present in OCs, interfere with the natural hormonal balance by reducing the endogenous hormone levels. Little is known how this affects the brain, especially during the most vulnerable times of brain maturation. Here, we review studies that investigate differences in brain gray and white matter in women using OCs in comparison to naturally cycling women. We focus on two neuroimaging methods used to quantify structural gray and white matter changes, namely structural MRI and diffusion MRI. Finally, we discuss the potential of these imaging techniques to advance knowledge about the effects of OCs on the brain and wellbeing in women.

Modeling hormonal contraception in female rats: A framework for studies in behavioral neurobiology

Research on hormonal contraceptives (HC) in animal models is lacking, and as a result, so is our understanding of the impact of HC on the brain and behavior. Here, we provide a review of the pharmacology of HC, as well as the methodology and best practices for designing a model of HC in female rats. We outline specific methodological considerations regarding dosing, route of administration, exposure time/timing, and selecting a control group. We also provide a framework outlining important levels of analysis for thinking about the impact of HC on behavioral and neurobiological outcomes. The purpose of this review is to equip researchers with foundational knowledge, and some basic elements of experimental design for future studies investigating the impact of HC on the brain and behavior of female rats.

Hormonal contraceptive usage influences stress hormone effects on cognition and emotion

Men and women partially differ in how they respond to stress and how stress in return affects their cognition and emotion. The influence of hormonal contraceptives (HCs) on this interaction has received little attention, which is surprising given the prevalence of HC usage. This selective review illustrates how HC usage modulates the effects of stress hormones on cognition and emotion. As three examples, we discuss stress hormone effects on episodic memory, fear conditioning and cognitive emotion regulation. The identified studies revealed that stress effects on cognitive-emotional processes in women using HCs were at times reduced or even absent when compared to men or naturally cycling women. Especially striking were the few examples of reversed effects in HC women. As underlying neuroendocrine mechanisms, we discuss influences of HCs on the neuroendocrine stress response and effects of HCs on central glucocorticoid sensitivity. The summarized findings emphasize the need for additional translational research.

The impact of hormonal contraceptives on anxiety treatments: From preclinical models to clinical settings

Exposure therapy is a central component of the first-line treatment for anxiety disorders, a common mental health condition that is twice as prevalent in women relative to men. A key underlying mechanism of exposure therapy is fear extinction, which is an active learning process supported by a neural circuitry that is highly regulated by ovarian hormones. This review synthesises research examining the impact of hormonal contraceptives on laboratory fear extinction tasks in female rats and women, and on exposure therapy in women with anxiety disorders. The evidence indicates that hormonal contraceptives have a detrimental impact on fear extinction and exposure therapy that is consistent across species, and from laboratory to clinical settings. Candidate pathways by which hormonal contraceptives impede fear extinction and exposure therapy include suppression of endogenous ovarian hormones and glucocorticoids, and downregulation of signalling pathways that support extinction learning. Key areas of focus for future research are discussed.

Hormonal contraceptives, stress, and the brain: The critical need for animal models

Hormonal contraceptives are among the most important health and economic developments in the 20thCentury, providing unprecedented reproductive control and a range of health benefits including decreased premenstrual symptoms and protections against various cancers. Hormonal contraceptives modulate neural function and stress responsivity. These changes are usually innocuous or even beneficial, including their effects onmood. However, in approximately 4-10% of users, or up to 30 million people at any given time, hormonal contraceptives trigger depression or anxiety symptoms. How hormonal contraceptives contribute to these responses and who is at risk for adverse outcomes remain unknown. In this paper, we discussstudies of hormonal contraceptive use in humans and describe the ways in which laboratory animal models of contraceptive hormone exposure will be an essential tool for expanding findings to understand the precise mechanisms by which hormonal contraceptives influence the brain, stress responses, and depression risk.

Oral contraceptives and stroke: Foes or friends

Incidents of strokes are increased in young women relative to young men, suggesting that oral contraceptive (OC) use is one of the causes of stroke among young women. Long-term exposures to the varying combinations of estrogen and progestogen found in OCs affect blood clotting, lipid and lipoprotein metabolism, endothelial function, and de novo synthesis of neurosteroids, especially brain-derived 17β-estradiol. The latter is essential for neuroprotection, memory, sexual differentiation, synaptic transmission, and behavior. Deleterious effects of OCs may be exacerbated due to comorbidities like polycystic ovary syndrome, sickle cell anemia, COVID-19, exposures to endocrine disrupting chemicals, and conventional or electronic cigarette smoking. The goal of the current review is to revisit the available literature regarding the impact of OC use on stroke, to explain possible underlying mechanisms, and to identify gaps in our understanding to promote future research to reduce and cure stroke in OC users.

Impact of hormonal contraceptives on sex differences in fear conditioning and fear extinction in PTSD

Sex differences in the neurobiological mechanisms involved in fear conditioning and extinction have been suggested to contribute to differential vulnerability for the development of posttraumatic stress disorder (PTSD) in women compared with men. Reproductive hormones, such as estradiol, have been shown to facilitate fear conditioning and extinction learning and may explain some of these differences. However, the effect of commonly used hormonal contraceptives on the neurobiological mechanisms of fear conditioning and extinction is poorly understood. A laboratory study was conducted in trauma-exposed men and women with and without full or partial PTSD to examine effects of sex and use of hormonal birth control on fear conditioning, fear extinction learning, and extinction retention. Participants underwent fear conditioning with stimuli that were paired (CS+) or unpaired (CS−) with shock. Extinction learning occurred 72 h later, and extinction retention was tested 1 wk after extinction. Women on hormonal contraceptives (HCs) demonstrated enhanced acquisition of fear conditioning and enhanced extinction of fear as compared with women off hormonal birth control and men. While clinical implications have yet to be determined, these results suggest that hormonal contraceptives may facilitate learning during both fear acquisition and extinction. Understanding the impact of sex and hormones on fear conditioning and extinction processes may lead to new insights into the pathophysiology of PTSD and result in advancements in treatment that may vary by sex.

Revisiting sex differences in the acquisition and extinction of threat conditioning in humans

Findings pertaining to sex differences in the acquisition and extinction of threat conditioning, a paradigm widely used to study emotional homeostasis, remain inconsistent, particularly in humans. This inconsistency is likely due to multiple factors, one of which is sample size. Here, we pooled functional magnetic resonance imaging (fMRI) and skin conductance response (SCR) data from multiple studies in healthy humans to examine sex differences during threat conditioning, extinction learning, and extinction memory recall. We observed increased functional activation in males, relative to females, in multiple parietal and frontal (medial and lateral) cortical regions during acquisition of threat conditioning and extinction learning. Females mainly exhibited higher amygdala activation during extinction memory recall to the extinguished conditioned stimulus and also while responding to the unconditioned stimulus (presentation of the shock) during threat conditioning. Whole-brain functional connectivity analyses revealed that females showed increased connectivity across multiple networks including visual, ventral attention, and somatomotor networks during late extinction learning. At the psychophysiological level, a sex difference was only observed during shock delivery, with males exhibiting higher unconditioned responses relative to females. Our findings point to minimal to no sex differences in the expression of conditioned responses during acquisition and extinction of such responses. Functional MRI findings, however, show some distinct functional activations and connectivities between the sexes. These data suggest that males and females might use different neural mechanisms, mainly related to cognitive processing, to achieve comparable levels of acquired conditioned responses to threating cues.