3alpha-reduced neuroactive steroids and their precursors during pregnancy and the postpartum period

New treatments: Opportunities and challenges

Across the spectrum of perinatal mental illness, there exist a variety of effective treatments. However, the available treatments are not always matched to the presentation, resources, constraints, or values of each patient. Furthermore, provider, local, and systemic factors complicate access to current treatment options. New and emerging approaches offer the potential of more effective treatment for specific perinatal psychiatric disorders. From neuroactive steroid medications to accelerated psychotherapy interventions, recent innovations have demonstrated enhanced efficacy on a faster timeline. Optimally, these developments will also lower barriers to care but this is not necessarily true. We review novel and upcoming interventions across perinatal mental illness and place them in the context of existing treatments and common challenges.

Allopregnanolone in the peripartum: Correlates, concentrations, and challenges - A systematic review

BACKGROUND

Allopregnanolone (ALLO) is a metabolite of progesterone and a neuroactive steroid hormone. As a positive allosteric modulator of gamma-aminobutyric acid (GABA) receptors, ALLO seems to have antidepressant and anxiolytic effects, and was therefore approved as a specific medication for the treatment of postpartum depression in 2019. Despite the growing number of publications investigating ALLO levels, results on the biological and psychological correlates in the peripartum period remain inconsistent, possibly due to methodological challenges regarding measurement. To date, however, there is no systematic review examining the correlates, concentrations, and challenges in measuring ALLO in peripartum women.

METHOD

A systematic literature search of PubMed and PsycINFO was conducted in August 2023. Original research articles that measured ALLO concentrations in peripartum women were included. Reports were excluded if they were not original research, included non-human subjects, did not include peripartum women, did not include ALLO measurement as an outcome, included (pharmacological) interventions, constituted method validations, or used the same cohort as another study.

RESULTS

The literature search yielded 234 articles, and two articles were identified from other sources. After full-text screening, 19 articles (N = 1401) met the inclusion criteria, of which seven focused on biological correlates of ALLO and 12 on mood correlates. Of the latter, six found no association between ALLO and mood, four found a negative association, and two found a positive association. Overall, the results show an increase in ALLO levels during pregnancy and a decrease after birth, with levels then remaining low until six months postpartum. ALLO was most commonly measured in blood plasma and by gas chromatography-mass spectrometry (GC-MS). A significant matrix effect was found for blood serum and a significant method effect for radioimmunoassays (RIAs). A significant effect of time of measurement was found.

CONCLUSION

ALLO measurement shows method and matrix effects. ALLO levels are higher when measured in serum compared to in plasma, and when measured using RIA compared to other methods. Time of measurement, study design, and standardization of measurement also influence the reliability of measurement and the interpretation of results.

Mid-pregnancy allopregnanolone levels and trajectories of perinatal depressive symptoms

Perinatal depression is a major cause of disability for individuals giving birth worldwide, with detrimental effects on short- and long-term parental and child outcomes. There is emerging evidence that the neuroactive steroid hormone allopregnanolone is implicated in the pathophysiology and course of perinatal mood symptoms. However, no study thus far has examined allopregnanolone levels whilst making use of longitudinal data on depressive symptom trajectories throughout the perinatal period. The present study investigated levels of allopregnanolone at gestational week 17 of 252 participants in relation to perinatal depressive symptom trajectories, with a secondary aim of exploring the role of history of depression as an effect modifier. Four perinatal depressive symptom trajectories were investigated: controls (no depressive symptoms throughout perinatal period) (N=161), antepartum (depressive symptoms prenatally with postpartum remission) (N=31), postpartum-onset (no depressive symptoms during pregnancy, development of depressive symptoms postpartum) (N=23), and persistent (depressive symptoms throughout the perinatal period) (N=37). Results show that for every one nmol/l increase in allopregnanolone, there was 7% higher odds for persistent depressive symptoms (OR 1.07, 95% CI 1.01-1.14) compared to controls. No association was seen for antepartum and postpartum-onset depressive symptoms. History of depression did not modify the association between allopregnanolone and perinatal depressive symptom trajectories. These results show the role of allopregnanolone for persistent depressive symptoms and strengthen the hypothesis of differences in pathophysiology among the trajectories.

Neuroendocrine insights into neurosteroid therapy for postpartum depression

Postpartum depression (PPD) is associated with a decline in progesterone-derived anxiolytic-antidepressant neurosteroids after delivery. Neurosteroid replacement therapy (NRT) with GABA-A receptor-modulating allopregnanolone (brexanolone) shows promise as the first drug treatment for PPD. Here we describe the molecular insights of the neurosteroid approach for rapid relief of PPD symptoms compared with traditional antidepressants.

Metabolites of progesterone in pregnancy: Associations with perinatal anxiety

BACKGROUND

Anxiety disorders are the most common psychiatric disorder during the perinatal period and one of the major risk factors for postpartum depression, yet we know little about biological factors in the etiology of perinatal anxiety. A growing literature points to neuroactive steroid (NAS) dysregulation in perinatal mental illness, but directionality has not been clearly demonstrated, results are not consistent, and no studies have investigated NAS in a population with pure anxiety without comorbid depression. We aimed to add to the limited literature by examining the association between anxiety without comorbid depression and metabolic pathways of NAS longitudinally across the peripartum.

METHODS

We measured anxiety symptoms by psychological scales and NAS levels using Gas Chromatography-Mass Spectrometry (GC-MS) at the second and third trimester (T2 and T3) and week 6 postpartum (W6) in n = 36 women with anxiety and n = 38 healthy controls. The anxiety group was determined by a data-driven approach, and cross-sectional and longitudinal statistical methods were used to examine the relationship between the study population and NAS.

RESULTS

We found that anxiety had a significant moderating effect on the relationship between progesterone and allopregnanolone, with no such effect for the relationships between progesterone and the intermediate (5α-DHP) or isomeric (isoallopregnanolone) compounds in this pathway, and no effects on the corresponding pathway converting progesterone to pregnanolone and epipregnanolone. We also found a less precipitous decline in the ratio of allopregnanolone to progesterone between T3 and W6 in the anxiety group compared to the non-anxiety group. A genotype analysis of a single-nucleotide polymorphism in the AKR1C2 gene demonstrated that the relationship of allopregnanolone to the intermediate metabolite, 5α-DHP, differed by genotype.

CONCLUSION

Our exploratory findings indicate that, for pregnant people with anxiety, metabolism is shunted more aggressively toward the endpoint of the progesterone to allopregnanolone metabolic pathway than it is for those without anxiety.

Preclinical and clinical pharmacology of brexanolone (allopregnanolone) for postpartum depression: a landmark journey from concept to clinic in neurosteroid replacement therapy

This article describes the critical role of neurosteroids in postpartum depression (PPD) and outlines the landmark pharmacological journey of brexanolone as a first-in-class neurosteroid antidepressant with significant advantages over traditional antidepressants. PPD is a neuroendocrine disorder that affects about 20% of mothers after childbirth and is characterized by symptoms including persistent sadness, fatigue, dysphoria, as well as disturbances in cognition, emotion, appetite, and sleep. The main pathology behind PPD is the postpartum reduction of neurosteroids, referred to as neurosteroid withdrawal, a concept pioneered by our preclinical studies. We developed neurosteroid replacement therapy (NRT) as a rational approach for treating PPD and other conditions related to neurosteroid deficiency, unveiling the power of neurosteroids as novel anxiolytic-antidepressants. The neurosteroid, brexanolone (BX), is a progesterone-derived allopregnanolone that rapidly relieves anxiety and mood deficits by activating GABA-A receptors, making it a transformational treatment for PPD. In 2019, the FDA approved BX, an intravenous formulation of allopregnanolone, as an NRT to treat PPD. In clinical studies, BX significantly improved PPD symptoms within hours of administration, with tolerable side effects including headache, dizziness, and somnolence. We identified the molecular mechanism of BX in a neuronal PPD-like milieu. The mechanism of BX involves activation of both synaptic and extrasynaptic GABA-A receptors, which promote tonic inhibition and serve as a key target for PPD and related conditions. Neurosteroids offer several advantages over traditional antidepressants, including rapid onset, unique mechanism, and lack of tolerance upon repeated use. Some limitations of BX therapy include lack of aqueous solubility, limited accessibility, hospitalization for treatment, lack of oral product, and serious adverse events at high doses. However, the unmet need for synthetic neurosteroids to address this critical condition supersedes these limitations. Recently, we developed novel hydrophilic neurosteroids with a superior profile and improved drug delivery. Overall, approval of BX is a major milestone in the field of neurotherapeutics, paving the way for the development of novel synthetic neurosteroids to treat depression, epilepsy, and status epilepticus.

Adrenocorticotropic hormone secretion in response to anticipatory stress and venepuncture: The role of menstrual phase and oral contraceptive use

INTRODUCTION

Oral contraceptives (OCs) are primarily known for their effects on the reproductive system, but they can also impact the hypothalamic-pituitary-adrenal (HPA) axis. The present study aimed to compare plasma adrenocorticotropic hormone (ACTH) responses to the anticipatory stress of participating in a scientific experiment and venepuncture in OC users versus naturally cycling (NC) women, with a focus on variations throughout the menstrual cycle.

METHODS

We recruited 131 young women (average age 20.5) and obtained blood samples to measure plasma ACTH concentrations immediately after venepuncture and again after 15 min of group activities designed to facilitate interpersonal attachment and stress-buffering.

RESULTS

ACTH levels decreased in 70% of all participants throughout the group activities. A two-way repeated measures ANOVA highlighted a significant interaction between time and OC use, indicating differential changes in ACTH levels during social interaction between OC users and NC women. Further, the post-hoc analysis revealed that a period of stress-buffering group activities significantly decreased ACTH levels in NC women during menstrual and secretory phases, but not during the proliferative phase. In contrast, OC users did not display a decrease during group activities, regardless of the phase.

CONCLUSION

This study underscores the influence of OC use on stress regulation, demonstrating that OCs not only modulate reproductive functions but also impact ACTH stress reactivity. Additionally, it emphasizes the importance of considering hormonal contraceptive use and menstrual cycle phases when assessing female stress responses.

Biological Mechanisms in Pregnant Women With Anxiety (Happy Mother-Healthy Baby Supplement Study): Protocol for a Longitudinal Mixed Methods Observational Study

BACKGROUND

Anxiety and depression are common in the perinatal period and negatively affect the health of the mother and baby. Our group has developed "Happy Mother-Healthy Baby" (HMHB), a cognitive behavioral therapy-based psychosocial intervention to address risk factors specific to anxiety during pregnancy in low- and middle-income countries (LMICs).

OBJECTIVE

The purpose of this study is to examine biological mechanisms that may be linked to perinatal anxiety in conjunction with a randomized controlled trial of HMHB in Pakistan.

METHODS

We are recruiting 120 pregnant women from the Holy Family Hospital, a public facility in Rawalpindi, Pakistan. Participants are assessed for at least mild anxiety symptoms using the Hospital Anxiety and Depression Scale (ie, a score ≥8 on the anxiety scale is necessary for inclusion in the anxiety groups and <8 for inclusion in the healthy control group). Women who meet the criteria for an anxiety group are randomized into either the HMHB intervention group or an enhanced usual care (EUC) control group. Participants receive HMHB or EUC throughout pregnancy and undergo blood draws at 4 time points (baseline, second trimester, third trimester, and 6 weeks post partum). We will assess peripheral cytokine concentrations using a multiplex assay and hormone concentrations using gas chromatography and mass spectrometry. The statistical analysis will use generalized linear models and mixed effects models to assess the relationships across time among anxiety, immune dysregulation, and hormone levels, and to assess whether these biological factors mediate the relationship between anxiety and birth and child development outcomes.

RESULTS

Recruitment started on October 20, 2020, and data collection was completed on August 31, 2022. The start date for recruitment for this biological supplement study was delayed by approximately half a year due to the COVID-19 pandemic. The trial was registered at ClinicalTrials.gov (NCT03880032) on September 22, 2020. The last blood samples were shipped to the United States on September 24, 2022, where they will be processed for analysis.

CONCLUSIONS

This study is an important addition to the HMHB randomized controlled trial of an intervention for antenatal anxiety. The intervention itself makes use of nonspecialist providers and, if effective, will represent an important new tool for the treatment of antenatal anxiety in LMICs. Our biological substudy is one of the first attempts to link biological mechanisms to antenatal anxiety in an LMIC in the context of a psychosocial intervention, and our findings have the potential to significantly advance our knowledge of the biological pathways of perinatal mental illness and treatment efficacy.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03880032; https://clinicaltrials.gov/ct2/show/NCT03880032.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/43193.

Prenatal Stress Induces Translational Disruption Associated with Myelination Deficits

Disruptions to neurodevelopment are known to be linked to behavioral disorders in childhood and into adulthood. The fetal brain is extremely vulnerable to stimuli that alter inhibitory GABAergic pathways and critical myelination processes, programing long-term neurobehavioral disruption. The maturation of the GABAergic system into the major inhibitory pathway in the brain and the development of oligodendrocytes into mature cells capable of producing myelin are integral components of optimal neurodevelopment. The current study aimed to elucidate prenatal stress-induced mechanisms that disrupt these processes and to delineate the role of placental pathways in these adverse outcomes. Pregnant guinea pig dams were exposed to prenatal stress with strobe light exposure for 2 h/day on gestational age (GA) 35, 40, 45, 50, 55, 60, and 65, and groups of fetuses and placentae were collected after the stress exposure on GA40, GA50, GA60, and GA69 (term). Fetal plasma, placental, and brain tissue were collected for allopregnanolone and cortisol quantification with ELISA. Relative mRNA expression of genes of specific pathways of interest was examined with real-time PCR in placental and hippocampal tissue, and myelin basic protein (MBP) was quantified immunohistochemically in the hippocampus and surrounding regions for assessment of mature myelin. Prenatal stress in mid-late gestation resulted in disruptions to the translational machinery responsible for the production of myelin and decreased myelin coverage in the hippocampus and surrounding regions. The male placenta showed an initial protective increase in allopregnanolone concentrations in response to maternal psychosocial stress. The male and female placentae had a sex-dependent increase in neurosteroidogenic enzymes at term following prenatal stress. Independent from exposure to prenatal stress, at gestational day 60 - a critical period for myelin development, the placentae of female fetuses had increased capability of preventing cortisol transfer to the fetus through expression of 11-beta-hydroxysteroid dehydrogenase types 1 and 2. The deficits early in the process of maturation of myelination indicate that the reduced myelination observed at childhood equivalence in previous studies begins in fetal life. This negative programing persists into childhood, potentially due to dysregulation of MBP translation processes. Expression patterns of neurosteroidogenic enzymes in the placenta at term following stress may identify at-risk fetuses that have been exposed to a stressful in utero environment.

Progesterone and Its Metabolites Play a Beneficial Role in Affect Regulation in the Female Brain

Premenstrual dysphoric disorder is a female affective disorder that is defined by mood symptoms. The condition is linked to unstable progesterone concentrations. Progestin supplementation is given in cases of threatened or recurrent miscarriage and for luteal phase support. Progesterone is essential for implantation, immune tolerance, and modulation of uterine contractility. For a long time, the administration of progestins was associated with an unfavorable impact on mood, leading to negative affect, and, therefore, was contraindicated in existing mood disorders. Establishing the role of the natural progesterone derivative allopregnanolone in advances in the treatment of postpartum depression has shed new light on the general pathophysiology of mood disorders. Allopregnanolone directly interacts with gamma-aminobutyric acid type A (GABA-A) receptors even at nanomolar concentrations and induces significant anti-depressant, anti-stress, sedative, and anxiolytic effects. Postpartum depression is caused by a rapid drop in hormones and can be instantly reversed by the administration of allopregnanolone. Premenstrual dysphoric disorder can also be considered to result from insufficient neuroactive steroid action due to low progesterone derivative concentration, unstable hormone levels, or decreased receptor sensitivity. The decrease in progesterone levels in perimenopause is also associated with affective symptoms and an exacerbation of some psychosomatic syndromes. Bioidentical progesterone supplementation encounters several obstacles, including limited absorption, first-pass effect, and rapid metabolism. Hence, non-bioidentical progestins with better bioavailability were widely applied. The paradoxical, unfavorable effect of progestins on mood can be explained by the fact that progestins suppress ovulation and disturb the endocrine function of the ovary in the luteal phase. Moreover, their distinct chemical structure prevents their metabolism to neuroactive, mood-improving derivatives. A new understanding of progesterone-related mood disorders can translate the study results from case series and observational studies to cohort studies, clinical trials, and novel, effective treatment protocols being developed.

Clinical Implications of the Neurosteroid Allopregnanolone in Reproductive Depression

Certain women develop depression with fluctuations in hormone levels whereas other women do not; this hormonally driven depression has been termed reproductive depression. The pathophysiology of reproductive depression differs from that of major depressive disorder, and this distinction has important clinical-including treatment-implications. Recent advances have revealed that the neurosteroid, allopregnanolone, plays a central role in reproductive depression. Appreciation of allopregnanolone's role in reproductive depression aids in selecting targeted treatments and in predicting symptom worsening during subsequent reproductive stages, and it can be used to reduce risk of relapse. This knowledge is also guiding the development of new pharmacologic treatments for reproductive depression.

A Nested Case-Control Study of Allopregnanolone and Preterm Birth in the Healthy Start Cohort

Context

Chronic stress is a risk factor for preterm birth; however, objective measures of stress in pregnancy are limited. Maternal stress biomarkers may fill this gap. Steroid hormones and neurosteroids such as allopregnanolone (ALLO) play important roles in stress physiology and pregnancy maintenance and therefore may be promising for preterm birth prediction.

Objective

We evaluated maternal serum ALLO, progesterone, cortisol, cortisone, pregnanolone, and epipregnanolone twice in gestation to evaluate associations with preterm birth.

Methods

We performed a nested case-control study using biobanked fasting serum samples from the Healthy Start prebirth cohort. We included healthy women with a singleton pregnancy and matched preterm cases with term controls (1:1; N = 27 per group). We used a new HPLC-tandem mass spectrometry assay to quantify ALLO and five related steroids. We used ANOVA, Fisher exact, χ², t test, and linear and logistic regression as statistical tests.

Results

Maternal serum ALLO did not associate with preterm birth nor differ between groups. Mean cortisol levels were significantly higher in the preterm group early in pregnancy (13w0d-18w0d; P < 0.05) and higher early pregnancy cortisol associated with increased odds of preterm birth (at 13w0d; odds ratio, 1.007; 95% CI, 1.0002-1.014). Progesterone, cortisone, pregnanolone, and epipregnanolone did not associate with preterm birth.

Conclusion

The findings from our pilot study suggest potential utility of cortisol as a maternal serum biomarker for preterm birth risk assessment in early pregnancy. Further evaluation using larger cohorts and additional gestational timepoints for ALLO and the other analytes may be informative.

Lack of placental neurosteroid alters cortical development and female somatosensory function

Placental endocrine function is essential to fetal brain development. Placental hormones include neurosteroids such as allopregnanolone (ALLO), a regulator of neurodevelopmental processes via positive allosteric modulation of the GABAA receptor (GABAA-R). Using a mouse model (plKO) in which the gene encoding the ALLO synthesis enzyme is specifically deleted in trophoblasts, we previously showed that placental ALLO insufficiency alters cerebellar white matter development and leads to male-specific autistic-like behavior. We now demonstrate that the lack of placental ALLO causes female-predominant alterations of cortical development and function. Placental ALLO insufficiency disrupts cell proliferation in the primary somatosensory cortex (S1) in a sex-linked manner. Early changes are seen in plKO embryos of both sexes, but persist primarily in female offspring after birth. Adolescent plKO females show significant reduction in pyramidal neuron density, as well as somatosensory behavioral deficits as compared with plKO males and control littermates. Assessment of layer-specific markers in human postmortem cortices suggests that preterm infants may also have female-biased abnormalities in cortical layer specification as compared with term infants. This study establishes a novel and fundamental link between placental function and sex-linked long-term neurological outcomes, emphasizing the importance of the growing field of neuroplacentology.

Neurosteroids and early-life programming: An updated perspective

Early-life stress can lead to detrimental offspring outcomes, including an increased risk for mood disorders and hypothalamic-pituitary-adrenal axis dysregulation. Neurosteroids bind to ligand-gated neurotransmitter receptors, rapidly modulating neuronal excitability and promoting termination of stress responses. Reduced neurosteroidogenesis underlies some of the aberrant neuroendocrine and behavioural phenotypes observed in adult prenatally stressed rodents. During development, disruptions in neurosteroid generation and action also lead to long-term programming effects on the off-spring's brain and behaviour. Here, we review recent advances in the field, focusing on the interaction between neurosteroids and early-life stress outcomes in adulthood and in the perinatal period. We also discuss the direction of future research, with emphasis on quantification methods, sex differences, and neurosteroids as targets for therapeutic intervention.

Development of neuroactive steroids for the treatment of postpartum depression

Postpartum depression (PPD) is a common major depressive episode surrounding childbirth, with estimated rates ranging from 5.5% to 23.5% of all live births across Europe and the USA based on the presence of key symptoms. PPD has been associated with significant impairments in both maternal functioning and mother-infant attachment, and these impairments can have lasting effects on the emotional and cognitive development of children. Although the precise pathophysiology of PPD is unknown, preclinical findings suggest that large fluctuations in neurosteroid hormone levels can induce physiological plasticity in the expression of functional GABA_A receptors during pregnancy and the postpartum period, and that deficits in this plasticity may underpin a biological mechanism that contributes to the manifestation of depressive symptoms. Here, we review the controlled clinical trials to date that have assessed the efficacy of pharmacological treatments for PPD, including oestradiol, selective serotonin reuptake inhibitors, brexanolone (an iv formulation of allopregnanolone) and an investigational neuroactive steroid and GABA_A positive allosteric modulator, zuranolone. Coupled with the GABAergic deficits implicated in major depressive disorder, these findings highlight not only the potential role of GABA_A receptor plasticity in the pathophysiology of PPD, but also the novel therapeutic approach of using positive allosteric modulators targeting GABAergic transmission to treat women affected by PPD.

Relating neurosteroid modulation of inhibitory neurotransmission to behaviour

Studies in the 1980s revealed endogenous metabolites of progesterone and deoxycorticosterone to be potent, efficacious, positive allosteric modulators (PAMs) of the GABA_A receptor (GABA_A R). The discovery that such steroids are locally synthesised in the central nervous system (CNS) promoted the thesis that neural inhibition in the CNS may be "fine-tuned" by these neurosteroids to influence behaviour. In preclinical studies, these neurosteroids exhibited anxiolytic, anticonvulsant, analgesic and sedative properties and, at relatively high doses, induced a state of general anaesthesia, a profile consistent with their interaction with GABA_A Rs. However, realising the therapeutic potential of either endogenous neurosteroids or synthetic "neuroactive" steroids has proven challenging. Recent approval by the Food and Drug Administration of the use of allopregnanolone (brexanolone) to treat postpartum depression has rekindled enthusiasm for exploring their potential as new medicines. Although neurosteroids are selective for GABA_A Rs, they exhibit little or no selectivity across the many GABA_A R subtypes. Nevertheless, a relatively minor population of receptors incorporating the δ-subunit (δ-GABA_A Rs) appears to be an important contributor to their behavioural effects. Here, we consider how neurosteroids acting upon GABA_A Rs influence neuronal signalling, as well as how such effects may acutely and persistently influence behaviour, and explore the case for developing selective PAMs of δ-GABA_A R subtypes for the treatment of psychiatric disorders.

Maternal Experience Does Not Predict Fear Extinction and Anxiety-Like Behaviour in Primiparous Rats Post-weaning

Reproductive experience leads to long-lasting changes in anxiety-like behaviour and fear extinction, the laboratory model of exposure therapy for anxiety disorders. For example, fear extinction is influenced by estrous cycle in nulliparous (no reproductive experience) female rats, but this effect is abolished in primiparous (one reproductive experience) females. It is unclear whether such changes are driven by pregnancy, maternal experience of caring for offspring during the postpartum period, or a combination of both experiences. The present study sought to determine the influence of maternal experience (i.e., exposure to pups and mother-pup interactions) on fear extinction in primiparous rats. In Experiment 1, we tested whether pup exposure is necessary to mitigate estrous effects on fear extinction in primiparous rats. Age-matched nulliparous rats, primiparous rats, and primiparous rats who experienced pregnancy but not pup exposure, underwent fear conditioning on day 1 (2 months post-parturition), extinction training during proestrus (high sex hormones) or metestrus (low sex hormones) on day 2, and extinction recall on day 3. Replicating past research, nulliparous rats showed impaired extinction recall when they were extinguished during metestrus compared to proestrus. In contrast, primiparous rats with and without pup exposure showed comparable extinction recall irrespective of estrous phase. In Experiment 2, we assessed whether naturally-occurring variation in mother-pup interactions predict future fear extinction performance and anxiety-like behaviour. During the first week of lactation, primiparous rats were measured for maternal behaviours toward pups. Primiparous rats were then tested on the light-dark box and elevated plus maze to measure anxiety-like behaviour and underwent a fear extinction protocol 1 month post-weaning. We found no significant correlations between maternal behaviour and fear extinction outcomes or anxiety-like behaviour. Our findings suggest that pregnancy, not maternal experience, mitigates the impact of estrous cycle on fear extinction. In addition, natural variation in maternal experience does not appear to contribute to variability in future fear extinction outcomes or anxiety-like behaviour in primiparous rats.

Involvement of neurosteroids in the control of hypothalamic-pituitary-adrenal axis activity in pregnant sheep under basal and stressful conditions

Neurosteroids are synthesized locally in the brain, where they can modify neuronal functionality depending on the physiological state. A high correlation was demonstrated between the increasing activity of the hypothalamic-pituitary-adrenal (HPA) axis and allopregnanolone (AL) concentration in the cerebrospinal fluid in sheep during pregnancy. Therefore, the present study tested the hypothesis that blocking neurosteroid synthesis in the brain of a pregnant sheep would affect HPA axis activity under both basal and stressful conditions. Two groups of sheep in the fourth month of gestation (n = 7 each) were subjected to the following treatments: 1) intracerebroventricular (icv) infusion of vehicle for three days (C) and then icv infusion of finasteride (a total of 100 μg/240 μL/day) for three days (F), one week apart, and 2) icv infusion of vehicle for three days and application of stressful stimuli (isolation and partial movement restriction) on the third day (S), and subsequently icv infusion of finasteride for three days and application of stressful stimuli on the third day (SF), one week apart. On the third days of the experiment, a 4-h push-pull perfusion of the infundibular nucleus/median eminence and blood sampling were performed. Mean perfusate corticotropin-releasing hormone (CRH), plasma adrenocorticotropin (ACTH) and cortisol concentrations were significantly higher in sheep treated with finasteride, stress and finasteride in combination with stress compared to controls. The highest hormone concentrations in Groups F, S and SF, were recorded during the first 60 min; however, significant increases in CRH and ACTH levels were observed in Group SF towards the end of the experiment. It can be concluded that neurosteroids may be an essential component of the mechanism controlling HPA axis activity in pregnant sheep, not only under stress-free conditions, but more importantly, also by inhibiting the neuroendocrine response to stressors.

Neuroactive steroids and depression in early pregnancy

Progesterone (P4) can be metabolized to two general classes of neuroactive steroids (NAS) -those like allopregnanolone (ALLO) and pregnanolone (PA) which are positive allosteric modulators of the Gamma Aminobutyric Acid type A (GABAA) receptor and those like isoallopregnanolone (ISOALLO) and epipregnanolone (EPI) which are negative allosteric modulators of the GABAA receptor. While exogenous administration of ALLO is effective in treating postpartum depression, knowledge gaps remain in the dynamic interplay of NAS across the perinatal period. In particular little is known about ALLO and PA in relation to depression earlier in pregnancy, and the role of ISOALLO and EPI in relation to depression at any point in the perinatal period. In a prospective, nested case/control study in low-income women of color, we compared the metabolism of P4 to four NAS (i.e., ratios ALLO:P4, PA:P4, ISOALLO:P4, EPI:P4) in pregnant women with depression at either or both of the first and second trimesters (cases) and women without depression at either time point (controls). Fifty women (36% depressed, 56% Black, 28% Latina) completed depression screening using a computerized adaptive test of mental health (CAT-MH™) and provided blood serum samples in both trimesters. In longitudinal mixed effects models of both trimesters, PND cases showed higher ratios of ALLO:P4 (p = .002) and PA:P4 (p = .03) compared to controls. In regression models of only first trimester data, there was no significant difference in NAS ratios between cases and controls (p > .05). Conversely, in models of the second trimester, ratios of PA:P4 (p = .002) and ISOALLO:P4 (p = .01) were significantly higher in cases compared to controls, and ratios of ALLO:P4 (p = .08) and EPI:P4 (p = .1) also trended higher in cases. The most severe cases, those with depression at both trimesters, showed an increase in ALLO:P4 (p = .06) and EPI:P4 (p < .001) ratios from the first to the second trimester, whereas controls showed a decrease in these ratios. Secondary analyses confirmed higher levels of ALLO (p = .04) and PA (p = .07) overall in cases compared to controls, along with higher levels of PA (p = .005) and ISOALLO (p = .02) in the second trimester alone. This work suggests a dynamic relationship between NAS and PND; whereas low ALLO levels have been previously associated with postpartum depression, earlier in pregnancy a higher metabolism of P4 to ALLO (and higher ALLO levels) is associated with depression. Some women may show a hormone-sensitive depressive response to acute increases in NAS metabolism in early pregnancy.

Development and validation of an LC-MS/MS assay for the quantification of allopregnanolone and its progesterone-derived isomers, precursors, and cortisol/cortisone in pregnancy

Neuroactive steroids are potent neuromodulators that play a critical role in both maternal and fetal health during pregnancy. These stress-responsive compounds are reportedly low in women with perinatal depression and may be associated with poor pregnancy outcomes in animal models. Chronic stress is a risk factor for adverse birth outcomes. Simultaneous quantification of neuroactive steroids, in combination with stress hormones cortisol/cortisone, provides an opportunity to investigate the synergistic relationship of these analytes within the convenience of one assay. A simple, reliable, and sensitive method for quantifying these endogenous compounds is necessary for further research with the potential to advance clinical diagnostic tools during pregnancy. Analytes were extracted from serum with a simple protein precipitation using methanol and then separated and quantified using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). After online extraction, analytes were separated using an Agilent Poroschell 120, 50 × 4.6 mm, 2.7 μm particle size, EC-C18 analytical column. The reliable quantification range was from 0.78 to 1000 ng/mL. QC sample inter- and intraday trueness was between 90 and 110% while inter- and intraday imprecision was less than 10%. Extracted samples were stable up to 7 days at 4 °C and extraction recovery was above 95%. Serum samples from 54 women in pregnancy were analyzed using this method. Here, we provide a validated, fast, and specific assay with sufficient sensitivity that allows for simultaneous quantification of blood serum concentrations of allopregnanolone (3α-hydroxy-5α-pregnan-20-one), pregnanolone (3α-hydroxy-5β-pregnan-20-one), epipregnanolone (3β-hydroxy-5β-pregnan-20-one), pregnenolone, progesterone, cortisol, and cortisone in pregnancy for clinical study samples and clinical diagnostics.

Promising leads and pitfalls: a review of dietary supplements and hormone treatments to prevent postpartum blues and postpartum depression

Prevention of postpartum depression (PPD) is important because it typically has a 13% prevalence rate, impactful immediate symptoms with greater risk of suicide, and higher long-term risk of psychiatric symptoms in both the mother and family. There are no universal approaches across all childbearing women that have proven to be preventative for PPD, so it is hoped that dietary and/or hormonal interventions will be developed. There are some effective preventative approaches for PPD, such as psychotherapy and medical management, for the highest risk cases, like when there is a past history of a major depressive episode. The purpose is to review studies that assess dietary and hormonal interventions for prevention of PPD and/or postpartum blues, a high-risk state for PPD. Studies that assess dietary and hormonal interventions for prevention of PPD which included a comparison group were reviewed, including omega-3 fatty acids, mineral and vitamin supplements, amino acid combinations, allopregnanolone, progesterone, and thyroxine. Presently, development of dietary supplements and hormonal products for prevention of PPD is at an early stage with most trials showing results that are either preliminary, not definitive, trend level or variable across studies. Even so, a few directions are not recommended for further investigation such as progesterone and thyroxine. On the other hand, studies of allopregnanolone for prophylaxis of PPD are needed. Also, given the number of trend level findings and the multifactorial etiology of PPD, it may be prudent to investigate combined interventions rather than monotherapies. There is still a major need to develop a dietary supplement that creates resiliency against the biological changes in early postpartum associated with risk for mood disorders and/or PPD.

Allopregnanolone in mood disorders: Mechanism and therapeutic development

The neuroactive steroid allopregnanolone (ALLO) is an endogenous positive allosteric modulator of GABA type A receptor (GABA_AR), and the down-regulation of its biosynthesis have been attributed to the development of mood disorders, such as depression, anxiety and post-traumatic stress disorder (PTSD). ALLO mediated depression/anxiety involves GABAergic mechanisms and appears to be related to brain-derived neurotrophic factor (BDNF), dopamine receptor, glutamate neurotransmission, and Ca²⁺ channel. In the clinical, brexanolone, as a newly developed intravenous ALLO preparation, has been approved for the treatment of postpartum depression (PPD). In addition, traditional antidepressants such as selective serotonin reuptake inhibitor (SSRI) could reverse ALLO decline. Recently, the translocation protein (TSPO, 18 kDa), which involves in the speed-limiting step of ALLO synthesis, and ALLO derivatization have been identified as new directions for antidepressant therapy. This review provides an overview of ALLO researches in animal model and patients, discusses its role in the development and treatment of depression/anxiety, and directs its therapeutic potential in future.

The delivery of a placenta/fetus with high gonadal steroid production contributes to postpartum depressive symptoms

BACKGROUND

A correlation between gonadal steroids and depressive symptoms during the perinatal period has long been suggested; however, the underlying mechanism for this relationship remains unclear.

METHODS

This study was designed to examine the correlation between gonadal steroid concentrations of umbilical cord blood and postpartum depressive symptoms as well as longitudinal alterations in maternal plasma gonadal steroid concentrations among 204 perinatal women. The levels of postpartum depressive state at 1 month postpartum were evaluated using the Edinburgh Postnatal Depression Scale.

RESULTS

Umbilical progesterone, estradiol, and testosterone levels were significantly higher in infants delivered by depressed mothers (870.7 ± 281.7 ng/ml, 8607.7 ± 4354.6 pg/ml, and 2.5 ± 0.9 ng/ml, respectively) than those delivered by nondepressed mothers (741.3 ± 324.0 ng/ml, 5221.9 ± 3416.3 pg/ml, and 2.1 ± 0.6 ng/ml, p < .01, p < .05, and p < .05, respectively). Postpartum plasma progesterone levels of depressed mothers (3.5 ± 3.1 ng/ml) measured in the early postpartum period were significantly lower than those of nondepressed mothers (9.1 ± 9.7 ng/ml, p < .01). The decrease in progesterone from mid-pregnancy to the early postpartum period was significantly higher in depressed mothers than in nondepressed mothers. Subgroup analyses specific to primiparas or multiparas indicated that a significant drop of progesterone was seen only in primiparas.

CONCLUSION

The current study suggests that the delivery of a placenta/fetus with high gonadal steroid production may cause a wider range of fluctuations in maternal plasma gonadal steroid concentrations, which may be concurrent with postpartum depressive symptoms.

Impaired Oligodendrocyte Development Following Preterm Birth: Promoting GABAergic Action to Improve Outcomes

Preterm birth is associated with poor long-term neurodevelopmental and behavioral outcomes, even in the absence of obvious brain injury at the time of birth. In particular, behavioral disorders characterized by inattention, social difficulties and anxiety are common among children and adolescents who were born moderately to late preterm (32-37 weeks' gestation). Diffuse deficits in white matter microstructure are thought to play a role in these poor outcomes with evidence suggesting that a failure of oligodendrocytes to mature and myelinate axons is responsible. However, there remains a major knowledge gap over the mechanisms by which preterm birth interrupts normal oligodendrocyte development. In utero neurodevelopment occurs in an inhibitory-dominant environment due to the action of placentally derived neurosteroids on the GABA_A receptor, thus promoting GABAergic inhibitory activity and maintaining the fetal behavioral state. Following preterm birth, and the subsequent premature exposure to the ex utero environment, this action of neurosteroids on GABA_A receptors is greatly reduced. Coinciding with a reduction in GABAergic inhibition, the preterm neonatal brain is also exposed to ex utero environmental insults such as periods of hypoxia and excessive glucocorticoid concentrations. Together, these insults may increase levels of the excitatory neurotransmitter glutamate in the developing brain and result in a shift in the balance of inhibitory: excitatory activity toward excitatory. This review will outline the normal development of oligodendrocytes, how it is disrupted under excitation-dominated conditions and highlight how shifting the balance back toward an inhibitory-dominated environment may improve outcomes.

Progesterone, reproduction, and psychiatric illness

Mood and anxiety disorders are vastly overrepresented in women, and one important contributor to these differences is the fluctuation in sex steroids in women during the reproductive years. Considerable evidence supports a role for abnormal sensitivity to these hormonal fluctuations for some women, who develop mood symptoms associated with reproductive transitions. This chapter presents evidence of the role of endogenous progesterone and its metabolites in such mood symptoms, and then goes on to cover the evidence concerning exogenous progesterone's effects on mood. Overall, the literature does not support an association between exogenous progesterone and negative mood in the general population, but does indicate that subset of women may be vulnerable to such effects. Research is lacking on women with psychiatric illness.

Prenatal resident-intruder stress decreases levels of allopregnanolone in the cortex, hypothalamus, and midbrain of males, and increases levels in the hippocampus and cerebellum of female, juvenile rat offspring

Prenatal stress (PNS) can influence behaviors associated with cognition, reward and emotional regulation, which are controlled by brain areas such as the cortex, hippocampus, hypothalamus, midbrain and cerebellum. Allopregnanolone in these regions modulates behavioral and parasympathetic effects. The current study tested whether exposing pregnant dams to 5 days of resident-intruder stress on prenatal days 15-20 for 10 min altered the levels of allopregnanolone in cortex, hypothalamus, hippocampus, midbrain, and cerebellum of male and female juvenile offspring. In cortex, hypothalamus, and midbrain of male rats exposed to prenatal stress, levels of allopregnanolone were significantly lower compared to all other groups. In the hippocampus and cerebellum, among females exposed to prenatal stress levels were significantly higher compared to all other groups. These differences in allopregnanolone levels varying by prenatal stress, sex and brain regions provide insight in potential mechanism of stress regulation and etiopathophysiology of stress-related disorders.

"Rapid actions of the neurosteroid allopregnanolone on ovarian and hypothalamic steroidogenesis: Central and peripheral modulation"

The present study aimed to determine whether an i.c.v. administration of allopregnanolone (ALLO) rapidly modifies the hypothalamic and ovarian 3β-hydroxysteroid dehydrogenase (3β-HSD) enzymatic activity and gene expression in in vivo and ex vivo systems in pro-oestrus (PE) and dioestrus I (DI) rats. Animals were injected with vehicle, ALLO, bicuculline or bicuculline plus ALLO and were then killed. In the in vivo experiment, the hypothalamus, ovaries and serum were extracted and analysed. In the ex vivo experiment, the superior mesenteric ganglion - ovarian nerve plexus - ovary system was extracted and incubated during 120 minutes at 37 ºC. The serum and ovarian compartment fluids were used to determine progesterone by radioimmunoanalysis. In the in vivo experiments, ALLO caused a decrease in hypothalamic and ovarian 3β-HSD enzymatic activity during PE. During DI, ALLO increased hypothalamic and ovarian 3β-HSD activity and gene expression. The ovarian 3β-HSD activity increased in both stages in the ex vivo system; gene expression increased only during DI. ALLO induced an increase in serum progesterone only in D1 and in the ovarian incubation liquids in both stages. All findings were reversed by an injection of bicuculline before ALLO. Ovarian steroidogenic changes could be attributed to signals coming from ganglion neurones, which are affected by the acute central neurosteroid stimulation. The i.c.v. administration of ALLO via the GABAergic system altered 3β-HSD activity and gene expression, modulating the neuroendocrine axis. The present study reveals the action that ALLO exerts on the GABAA receptor in both the central and peripheral nervous system and its relationship with hormonal variations. ALLO is involved in the "fine tuning" of neurosecretory functions as a potent modulator of reproductive processes in female rats.

Realising the therapeutic potential of neuroactive steroid modulators of the GABAA receptor

In the 1980s particular endogenous metabolites of progesterone and of deoxycorticosterone were revealed to be potent, efficacious, positive allosteric modulators (PAMs) of the GABA_A receptor (GABA_AR). These reports were followed by the discovery that such steroids may be synthesised not only in peripheral endocrine glands, but locally in the central nervous system (CNS), to potentially act as paracrine, or autocrine "neurosteroid" messengers, thereby fine tuning neuronal inhibition. These discoveries triggered enthusiasm to elucidate the physiological role of such neurosteroids and explore whether their levels may be perturbed in particular psychiatric and neurological disorders. In preclinical studies the GABA_AR-active steroids were shown to exhibit anxiolytic, anticonvulsant, analgesic and sedative properties and at relatively high doses to induce a state of general anaesthesia. Collectively, these findings encouraged efforts to investigate the therapeutic potential of neurosteroids and related synthetic analogues. However, following over 30 years of investigation, realising their possible medical potential has proved challenging. The recent FDA approval for the natural neurosteroid allopregnanolone (brexanolone) to treat postpartum depression (PPD) should trigger renewed enthusiasm for neurosteroid research. Here we focus on the influence of neuroactive steroids on GABA-ergic signalling and on the challenges faced in developing such steroids as anaesthetics, sedatives, analgesics, anticonvulsants, antidepressants and as treatments for neurodegenerative disorders.

[GABAergic approach of postpartum depression: A translational review of literature]

INTRODUCTION

Prevalence of postpartum depression (PPD) ranges from 10 to 15 % of parturients. The impact of the PPD is major on the maternal bond and the health of both mother and child. Its physiopathological mechanisms appear to differ from other types of depression. Today, pharmacotherapy is based on nonspecific treatment, and recent therapeutic advances in this field require a comprehensive approach of the implication of the GABAergic system in the development of PPD. Neurosteroid levels during pregnancy and after parturition and the GABA-A-r modulation are thought to be involved in PPD.

OBJECTIVE

To evaluate if the GABAergic approach is relevant in postpartum depression management.

METHODS

We conducted a systematic review of literature based on the MEDLINE database with the following Medical Subject Headings (MeSH): "postpartum depression", "GABA", "ganaxolone", "brexanolone", "allopregnanolone", prior to September 2019. We selected articles in English: preclinical and clinical studies, literature review, observational and therapeutic studies.

RESULTS

Preclinical models (mouse and rat) show changes in GABAergic inhibition in the peripartum period and correlation between allopregnanolone and GABA-A-r plasticity. This plasticity in the peripartum period maintains levels of inhibition adapted despite increased neurosteroid levels. KO models for the GABA-A-r δ subunit develop depression and anxiety symptoms in the postpartum period, and a change in the expression of the gene coding for the GABA-R alpha-4 subunit was found. Artificial inhibition of progesterone metabolism during post-partum increased depression symptoms. GABAergic fluctuation seems to be interrelated with other systems such as those of oxytocins. A synthetic neurosteroid (SGE-516) was tested on mouse models of PPD, KO for δ-GABA-A-r or KCC2, and showed decreased depressive symptoms and better mothering. Clinical studies confirm neurosteroid fluctuation and changes in the GABAergic system during the peripartum period. Allopregnanolone is the neurosteroid the most studied in PPD, and it is elevated in the brain during the pregnancy. Studies disagree on the presence of significant differences in allopregnanolone plasma levels during pregnancy or postpartum between women with PPD or not. Women with a history of PPD have greater susceptibility to neurosteroid withdrawal. Imagery and genetical data also show a link between allopregnanolone and PPD. The GABA-A-r may not recover in time following a reduced number during pregnancy, and this mismatch between neurosteroid levels and their receptor may trigger PPD. Several randomized controlled trials investigated brexanolone administrated IV, a synthetic formulation of allopregnanolone, and demonstrated a rapid and well tolerated reduction in depressive symptoms. In March 2019 brexanolone obtained FDA approval in PPD indication under the name Zulresso. However, there are differences in the time of beginning of PPD, which could constitute different subgroups of this disease, and which physiopathology could respond to different mechanisms. Prenatal depression does not respond to a GABAergic approach, but women without any risk factor or previous mood disorder developing PPD in the weeks following childbirth could be particularly responsive to this kind of treatment.

CONCLUSION

Disability to modulate GABA-A-r expression during pregnancy and restore its previous state after parturition appears to trigger PPD. The GABAergic system is a promising pharmacotherapy target. From preclinical to clinical studies for about twenty years the GABAergic system has been incriminated and targeted in this challenging mental disease.

Brexanolone for the treatment of patients with postpartum depression

On March 19, 2019, the United States Food and Drug Administration (FDA) approved Zulresso (brexanolone) for intravenous use for the treatment of postpartum depression (PPD) in adult women. The decision was based on three recent clinical trials following an FDA priority review and breakthrough therapy designation. Brexanolone is now available through a restricted process called the Zulresso Risk Evaluation and Mitigation Strategy Program that requires the drug to be administered by a healthcare provider in a certified healthcare facility. Brexanolone represents an important new treatment option to address treatment-resistant depressive symptoms. In this article, we discuss the current critical need for PPD treatments, the mechanisms of brexanolone action, and the efficacy and drug safety studies that led to FDA approval. Additionally, we discuss some limitations of the current formulation, specific populations of women that might benefit from this treatment, and how new drugs on the horizon may increase the ability to treat PPD in a variety of patient populations.

Allopregnanolone and reproductive psychiatry: an overview

Psychiatric symptoms that coincide with reproductive transitions are related to changes in sex steroids, but studies show that this relationship is governed by individual women's vulnerability to change rather than by differences in level. There is growing interest in the role of allopregnanolone (ALLO), a 3-α reduced metabolite of progesterone and a strong allosteric modulator of the GABA_A receptor, in such symptoms, with enough evidence now across various times of reproductive transition to offer an overview of the role of this hormone in reproductive psychiatry. This review offers a brief overview, focusing on literature of the last 3 years, of the relationship between allopregnanolone and mood at menarche; in the menstrual cycle; in the peripartum; and in the menopausal transition. ALLO dysregulation is identified in all of these transitions and found to be associated with mood symptoms, although evidence of its exact role; its relationship to other systems; and directionality is not consistent.

Structural and Functional Biology of Aldo-Keto Reductase Steroid-Transforming Enzymes

Aldo-keto reductases (AKRs) are monomeric NAD(P)(H)-dependent oxidoreductases that play pivotal roles in the biosynthesis and metabolism of steroids in humans. AKR1C enzymes acting as 3-ketosteroid, 17-ketosteroid, and 20-ketosteroid reductases are involved in the prereceptor regulation of ligands for the androgen, estrogen, and progesterone receptors and are considered drug targets to treat steroid hormone-dependent malignancies and endocrine disorders. In contrast, AKR1D1 is the only known steroid 5β-reductase and is essential for bile-acid biosynthesis, the generation of ligands for the farnesoid X receptor, and the 5β-dihydrosteroids that have their own biological activity. In this review we discuss the crystal structures of these AKRs, their kinetic and catalytic mechanisms, AKR genomics (gene expression, splice variants, polymorphic variants, and inherited genetic deficiencies), distribution in steroid target tissues, roles in steroid hormone action and disease, and inhibitor design.

GABAA dysregulation as an explanatory model for late-onset postpartum depression associated with weaning and resumption of menstruation

It is well established that a subgroup of women are particularly vulnerable to affective dysregulation during times of hormonal fluctuation. One underrecognized reproductive transition may be late-onset postpartum depression (PPD) in the context of weaning from breastfeeding and the resumption of menstruation. The goal of this review is to propose a biologically plausible mechanism for affective dysregulation during these transitions. The relationship between affective symptoms and neurohormonal changes associated with weaning will be investigated through a hypothesis-driven review of relevant literature. Neurosteroids, like allopregnanolone (ALLO), are widely recognized for augmenting GABAergic inhibition and having a powerful anxiolytic effect (Belelli D and Lambert JL, Nature Reviews Neuroscience 6:565-575, 2005). However, when ALLO is administered after prolonged withdrawal, there may be a paradoxical anxiogenic effect (Smith et al., Psychopharmacology 186:323-333, 2006; Shen et al., Nat Neurosci 10:469-477, 2007). Weaning from breastfeeding is a physiologic example of fluctuating levels of ALLO after prolonged withdrawal. We propose that the complex hormonal milieu during weaning and resumption of menstruation may modify GABA_A receptors such that ALLO may contribute to rather than ameliorate depressive symptoms in vulnerable individuals. The proposed model provides an initial step for understanding the mechanisms by which the changing hormonal environment during weaning and resumption of menstruation may contribute to an increased risk of depression in a subgroup of women who are hormonally sensitive. Future research investigating this model would be valuable both to identify women at increased risk for developing mood symptoms late in postpartum and to inform treatment for this and related reproductive depressive disorders.

Neuroactive Steroids and Perinatal Depression: a Review of Recent Literature

PURPOSE OF REVIEW

The purpose of this review is to provide a theoretical explanation and a review of the recent literature concerning the role of neuroactive steroids in perinatal depression, and to use this information to suggest future directions of research.

RECENT FINDINGS

The bulk of the evidence on neuroactive steroids in perinatal depression concerns allopregnanolone. Recent studies have been mixed, with some studies finding a direct correlation between lower levels of allopregnanolone and increased depressive symptoms but other studies finding no relationship. Evidence concerning other neuroactive steroids and perinatal depression is sparse. Additional research is needed with larger sample sizes and better characterization across the perinatal period (rather than cross-sectionally). Because some studies point to a lag between neuroactive steroid dysregulation and subsequent symptoms, future research should consider interactions with other aspects of neuroactive steroid physiology, such as synthetic enzymes or receptor plasticity.

Disruptions to the cerebellar GABAergic system in juvenile guinea pigs following preterm birth

BACKGROUND

Children that are born preterm are at an increased risk of developing cognitive problems and behavioural disorders, such as attention deficit hyperactivity disorder (ADHD). There is increasing interest in the role of the cerebellum in these processes and the potential involvement of GABAergic pathways in neurodevelopmental disorders. We propose that preterm birth, and the associated loss of the trophic intrauterine environment, alters the development of the cerebellum, contributing to ongoing neurobehavioral disorders.

METHODS

Guinea pigs were delivered preterm (GA62) or spontaneously at term (GA69), and tissues collected at corrected postnatal day (PND) 28. Neurodevelopmental and GABAergic markers myelin basic protein (MBP), neuronal nuclei (NeuN), calbindin (Purkinje cells), and GAD67 (GABA synthesis enzyme) were analysed in cerebellar lobules IX and X by immunohistochemistry. Protein expression of GAD67 and GAT1 (GABA transporter enzyme) were quantified by western blot, whilst neurosteroid-sensitive GABA_A receptor subunits were measured by RT-PCR.

RESULTS

MBP immunostaining was increased in lobule IX of preterm males, and reduced in lobule X of preterm females when compared to their term counterparts. GAD67 staining was decreased in lobule IX and X of the preterm males, but only in lobule X of the preterm females compared to term cohorts for each sex. Internal granule cell layer width of lobule X was decreased in preterm cohorts of both sexes compared to terms. There were no differences between gestational age groups for NeuN staining, GAD67 and GAT1 protein expression as measured by western blotting, or GABA_A receptor subunits as measured by RT-PCR between preterm and term for either sex.

CONCLUSIONS

The present findings suggest that components of the cerebellar GABAergic system of the ex-preterm cerebellum are disrupted. The higher expression of myelin in the preterm males may be due to a deficit in axonal pruning, whereas females have a deficit in myelination at 28 corrected days of age. Together these ongoing alterations may contribute to the neurodevelopmental and behavioural disorders observed in those born preterm.

Effects of combined IUGR and prenatal stress on the development of the hippocampus in a fetal guinea pig model

Intrauterine growth restriction (IUGR) and maternal stress during pregnancy are two compromises that negatively impact neurodevelopment and increase the risk of developing later life neuropsychiatric disorders such as schizophrenia, depression and behavioural disorders. Neurosteroids, particularly allopregnanolone, are important in protecting the developing brain and promoting many essential neurodevelopmental processes. Individually, IUGR and prenatal stress (PS) reduce myelination and neurogenesis within affected fetal brains, however less information is available on the combined effects of these two disorders on the term fetal brain. This study aimed to investigate how IUGR and PS impairs the neurosteroid pathway when combined using a guinea pig model, and how these then disrupt the neurodevelopment of the fetus. Uterine artery blood flow restriction was performed at GA30-35 to induce growth restriction, whilst PS was induced by exposure of the dam to a strobe light during gestation commencing GA40 and repeated every 5 days. Exposure in this model caused reductions in hippocampal CA1 MBP immunostaining of male fetuses in both IUGR alone and IUGR+PS paradigms but only by IUGR in the subcortical white mater, compared with control males. Plasma allopregnanolone was reduced by both stressors irrespective of sex, whereas GFAP or MAP2 expression were not affected by either stressor. Female neurodevelopment, as assessed by these markers, was unimpeded by these compromises. The addition of prenatal stress did not further compound these deficits.

Lower allopregnanolone during pregnancy predicts postpartum depression: An exploratory study

Current evidence is mixed on the role of progesterone and its metabolites in perinatal mood and anxiety disorders. We measured second and third trimester (T2 and T3) progesterone (PROG) and allopregnanolone (ALLO) levels by ELISA and postpartum depression (PPD) by clinician interview (DSM-IV criteria) in 60 pregnant women with a prior diagnosis of a mood disorder. Methods included multivariate and logistic regression with general linear mixed effect models. We found that, after adjustment, every additional ng/mL of T2 ALLO resulted in a 63% (95% CI 13% to 84%, p=0.022) reduction in the risk of developing PPD. Our findings extend previous work connecting ALLO and depression within pregnancy, and indicate that the relationship between pregnancy ALLO and PPD is worth further exploration in a larger sample.

Increased anxiety-like phenotype in female guinea pigs following reduced neurosteroid exposure in utero

Neurosteroids are essential for aiding proper fetal neurodevelopment. Pregnancy compromises such as preterm birth, prenatal stress and intrauterine growth restriction are associated with an increased risk of developing behavioural and mood disorders, particularly during adolescence. These pathologies involve the premature loss or alteration of trophic steroid hormones reaching the fetus leading to impaired neurodevelopment. While the specific programming mechanisms are yet to be fully elucidated, in adult life, dysfunctions of allopregnanolone action are prevalent in individuals with depression, post-traumatic stress disorder and anxiety disorders. The objective of this study was to assess if changes in concentrations of the neurosteroid, allopregnanolone, may be a fetal programming factor in priming the brain towards a negative behavioural phenotype during the childhood to adolescent period using a guinea pig model. Pregnant guinea pigs received either vehicle (45% (2-hydroxypropyl)-β-cyclodextrin) or the 5α-reductase inhibitor, finasteride (25mg/kg maternal weight) from gestational age 60 until spontaneous delivery (∼71days gestation). Male and female offspring from vehicle and finasteride treated dams were tested at postnatal day 20 (juvenile-equivalence) in an open field arena, and hippocampus and amygdala subsequently assessed for neurological changes in markers of development and GABA production pathways 24h later. Females with reduced allopregnanolone exposure in utero displayed increased neophobic-like responses to a change in their environment compared to female controls. There were no differences in the neurodevelopmental markers assessed; MAP2, NeuN, MBP, GFAP or GAD67 between intrauterine finasteride or vehicle exposure, in either the hippocampus or amygdala whereas GAT1 staining was decreased. This study indicates that an intrauterine reduction in the supply of allopregnanolone programs vulnerability of female offspring to anxiety-like disorders in juvenility without impacting long term allopregnanolone concentrations.

Peripartum neuroactive steroid and γ-aminobutyric acid profiles in women at-risk for postpartum depression

Neuroactive steroids (NAS) are allosteric modulators of the γ-aminobutyric acid (GABA) system. NAS and GABA are implicated in depression. The peripartum period involves physiologic changes in NAS which may be associated with peripartum depression and anxiety. We measured peripartum plasma NAS and GABA in healthy comparison subjects (HCS) and those at-risk for postpartum depression (AR-PPD) due to current mild depressive or anxiety symptoms or a history of depression. We evaluated 56 peripartum medication-free subjects. We measured symptoms with the Hamilton Depression Rating Scale (HAM-D17), Hamilton Anxiety Rating Scale (HAM-A) and Spielberger State-Trait Anxiety Inventory-State (STAI-S). Plasma NAS and GABA were quantified by liquid chromatography-mass spectrometry. We examined the associations between longitudinal changes in NAS, GABA and depressive and anxiety symptoms using generalized estimating equation methods. Peripartum GABA concentration was 1.9±0.7ng/mL (p=0.004) lower and progesterone and pregnanolone were 15.8±7.5 (p=0.04) and 1.5±0.7ng/mL (p=0.03) higher in AR-PPD versus HCS, respectively. HAM-D17 was negatively associated with GABA (β=-0.14±0.05, p=0.01) and positively associated with pregnanolone (β=0.16±0.06, p=0.01). STAI-S was positively associated with pregnanolone (β=0.11±0.04, p=0.004), allopregnanolone (β=0.13±0.05, p=0.006) and pregnenolone (β=0.02±0.01, p=0.04). HAM-A was negatively associated with GABA (β=-0.12±0.04, p=0.004) and positively associated with pregnanolone (β=0.11±0.05, p=0.05). Altered peripartum NAS and GABA profiles in AR-PPD women suggest that their interaction may play an important role in the pathophysiology of peripartum depression and anxiety.

Maternal Serum Lipid, Estradiol, and Progesterone Levels in Pregnancy, and the Impact of Placental and Hepatic Pathologies

OBJECTIVE

Lipids and steroid hormones are closely linked. While cholesterol is the substrate for (placental) steroid hormone synthesis, steroid hormones regulate hepatic lipid production. The aim of this study was to quantify circulating steroid hormones and lipid metabolites, and to characterize their interactions in normal and pathological pregnancies with a focus on hepatic and placental pathologies.

METHODS

A total of 216 serum samples were analyzed. Group A consisted of 32 patients with uncomplicated pregnancies who were analyzed at three different time-points in pregnancy (from the first through the third trimester) and once post partum. Group B consisted of 36 patients (24th to 42nd week of gestation) with pregnancy pathologies (IUGR n = 10, preeclampsia n = 13, HELLP n = 6, intrahepatic cholestasis n = 7) and 31 controls with uncomplicated pregnancies. Steroid profiles including estradiol, progesterone, and dehydroepiandrosterone were measured by GC-MS and compared with lipid concentrations.

RESULTS

In Group A, cholesterol and triglycerides correlated positively with estradiol (cholesterol ρ = 0.50, triglycerides ρ = 0.57) and progesterone (ρ = 0.49, ρ = 0.53) and negatively with dehydroepiandrosterone (ρ = - 0.47, ρ = - 0.38). Smoking during pregnancy affected estradiol concentrations, leading to lower levels in the third trimester compared to non-smoking patients (p < 0.05). In Group B, cholesterol levels were found to be lower in IUGR pregnancies and in patients with HELLP syndrome compared to controls (p < 0.05). Steroid hormone concentrations of estradiol (p < 0.05) and progesterone (p < 0.01) were lower in pregnancies with IUGR.

DISCUSSION

Lipid and steroid levels were affected most in IUGR pregnancies, while only minor changes in concentrations were observed for other pregnancy-related disorders. Each of the analyzed entities displayed specific changes. However, since the changes were most obvious in pregnancies complicated by IUGR and only minor changes were observed in pregnancies where patients had impaired liver function, our data suggests that placental rather than maternal hepatic function strongly determines lipid and steroid levels in pregnancy.

Neurosteroidogenesis Today: Novel Targets for Neuroactive Steroid Synthesis and Action and Their Relevance for Translational Research

Neuroactive steroids are endogenous neuromodulators synthesised in the brain that rapidly alter neuronal excitability by binding to membrane receptors, in addition to the regulation of gene expression via intracellular steroid receptors. Neuroactive steroids induce potent anxiolytic, antidepressant, anticonvulsant, sedative, analgesic and amnesic effects, mainly through interaction with the GABAA receptor. They also exert neuroprotective, neurotrophic and antiapoptotic effects in several animal models of neurodegenerative diseases. Neuroactive steroids regulate many physiological functions, such as the stress response, puberty, the ovarian cycle, pregnancy and reward. Their levels are altered in several neuropsychiatric and neurological diseases and both preclinical and clinical studies emphasise a therapeutic potential of neuroactive steroids for these diseases, whereby symptomatology ameliorates upon restoration of neuroactive steroid concentrations. However, direct administration of neuroactive steroids has several challenges, including pharmacokinetics, low bioavailability, addiction potential, safety and tolerability, which limit its therapeutic use. Therefore, modulation of neurosteroidogenesis to restore the altered endogenous neuroactive steroid tone may represent a better therapeutic approach. This review summarises recent approaches that target the neuroactive steroid biosynthetic pathway at different levels aiming to promote neurosteroidogenesis. These include modulation of neurosteroidogenesis through ligands of the translocator protein 18 kDa and the pregnane xenobiotic receptor, as well as targeting of specific neurosteroidogenic enzymes such as 17β-hydroxysteroid dehydrogenase type 10 or P450 side chain cleavage. Enhanced neurosteroidogenesis through these targets may be beneficial not only for neurodegenerative diseases, such as Alzheimer's disease and age-related dementia, but also for neuropsychiatric diseases, including alcohol use disorders.

Neurosteroids and GABAergic signaling in health and disease

Endogenous neurosteroids such as allopregnanolone, allotetrahydrodeoxycorticosterone, and androstanediol are synthesized either de novo in the brain from cholesterol or are generated from the local metabolism of peripherally derived progesterone or corticosterone. Fluctuations in neurosteroid concentrations are important in the regulation of a number of physiological responses including anxiety and stress, reproductive, and sexual behaviors. These effects are mediated in part by the direct binding of neurosteroids to γ-aminobutyric acid type-A receptors (GABAARs), resulting in the potentiation of GABAAR-mediated currents. Extrasynaptic GABAARs containing the δ subunit, which contribute to the tonic conductance, are particularly sensitive to low nanomolar concentrations of neurosteroids and are likely their preferential target. Considering the large charge transfer generated by these persistently open channels, even subtle changes in neurosteroid concentrations can have a major impact on neuronal excitability. Consequently, aberrant levels of neurosteroids have been implicated in numerous disorders, including, but not limited to, anxiety, neurodegenerative diseases, alcohol abuse, epilepsy, and depression. Here we review the modulation of GABAAR by neurosteroids and the consequences for health and disease.

Effect of postnatal progesterone therapy following preterm birth on neurosteroid concentrations and cerebellar myelination in guinea pigs

Allopregnanolone protects the fetal brain and promotes normal development including myelination. Preterm birth results in the early separation of the infant from the placenta and consequently a decline in blood and brain allopregnanolone concentrations. Progesterone therapy may increase allopregnanolone and lead to improved oligodendrocyte maturation. The objectives of this study were to examine the efficacy of progesterone replacement in augmenting allopregnanolone concentrations during the postnatal period and to assess the effect on cerebellar myelination – a region with significant postnatal development. Preterm guinea pig neonates delivered at 62 days of gestation by caesarean section received daily s.c. injections of vehicle (2-Hydroxypropyl-β-cyclodextrin) or progesterone (16 mg/kg) for 8 days until term-equivalent age (TEA). Term delivered controls (PND1) received vehicle. Neonatal condition/wellbeing was scored, and salivary progesterone was sampled over the postnatal period. Brain and plasma allopregnanolone concentrations were measured by radioimmunoassay; cortisol and progesterone concentrations were determined by enzyme immunoassay; and myelin basic protein (MBP), proteolipid protein (PLP), oligodendroctye transcription factor 2 (OLIG2) and platelet-derived growth factor receptor-α (PDGFRα) were quantified by immunohistochemistry and western blot. Brain allopregnanolone concentrations were increased in progesterone-treated neonates. Plasma progesterone and cortisol concentrations were elevated in progesterone-treated male neonates. Progesterone treatment decreased MBP and PLP in lobule X of the cerebellum and total cerebellar OLIG2 and PDGFRα in males but not females at TEA compared with term animals. We conclude that progesterone treatment increases brain allopregnanolone concentrations, but also increases cortisol levels in males, which may disrupt developmental processes. Consideration should be given to the use of non-metabolizable neurosteroid agonists.

Quantification of neurosteroids during pregnancy using selective ion monitoring mass spectrometry

Analytical techniques used to quantify neurosteroids in biological samples are often compromised by non-specificity and limited dynamic range which can result in erroneous results. A relatively rapid and inexpensive gas chromatography-mass spectrometry (GC-MS) was developed to simultaneously measure nine neurosteroids, including allopregnanolone, estradiol, and progesterone, as well as 25-hydroxy-vitamin D3 in plasma samples collected from adult women subjects during and after pregnancy. Sample preparation involved solid-phase extraction and derivatization, followed by automated injection on a GC equipped with a mass selective detector (MSD) operated in single ion monitoring (SIM) mode to yield a run time of less than 11min. Method detection limits for all neurosteroids ranged from 30 to 200pg/mL (parts per trillion), with coefficients of variation that ranged from 3% to 5% based on intra-assay comparisons run in triplicate. Although concentrations of estradiol measured by chemiluminescent immunoassay (CIA) were consistent with values determined by GC-MS values, CIA yielded considerable higher values of progesterone, suggesting antibody cross reactions resulting from low specificity. Mean neurosteroid levels and representative time-course data demonstrate the ability of the method to quantify changes in multiple neurosteroids during pregnancy, including rapid declines in neurosteroid levels associated with delivery. This simplified GC-MS method holds particular promise for research and clinical laboratories that require simultaneous quantification of multiple neurosteroids, but lack the resources and expertise to support advanced liquid chromatography-tandem mass spectrometry facilities.

Anxiety disorders and GABA neurotransmission: a disturbance of modulation

Lines of evidence coming from many branches of neuroscience indicate that anxiety disorders arise from a dysfunction in the modulation of brain circuits which regulate emotional responses to potentially threatening stimuli. The concept of anxiety disorders as a disturbance of emotional response regulation is a useful one as it allows anxiety to be explained in terms of a more general model of aberrant salience and also because it identifies avenues for developing psychological, behavioral, and pharmacological strategies for the treatment of anxiety disorder. These circuits involve bottom-up activity from the amygdala, indicating the presence of potentially threatening stimuli, and top-down control mechanisms originating in the prefrontal cortex, signaling the emotional salience of stimuli. Understanding the factors that control cortical mechanisms may open the way to identification of more effective cognitive behavioral strategies for managing anxiety disorders. The brain circuits in the amygdala are thought to comprise inhibitory networks of γ-aminobutyric acid-ergic (GABAergic) interneurons and this neurotransmitter thus plays a key role in the modulation of anxiety responses both in the normal and pathological state. The presence of allosteric sites on the GABAA receptor allows the level of inhibition of neurons in the amygdala to be regulated with exquisite precision, and these sites are the molecular targets of the principal classes of anxiolytic drugs. Changes in the levels of endogenous modulators of these allosteric sites as well as changes in the subunit composition of the GABAA receptor may represent mechanisms whereby the level of neuronal inhibition is downregulated in pathological anxiety states. Neurosteroids are synthesized in the brain and act as allosteric modulators of the GABAA receptor. Since their synthesis is itself regulated by stress and by anxiogenic stimuli, targeting the neurosteroid-GABAA receptor axis represents an attractive target for the modulation of anxiety.

Increased placental neurosteroidogenic gene expression precedes poor outcome in the preterm guinea pig

Placental 5α-reductase (5αR) is influenced by in utero compromises and has a role in regulating neuroactive steroid concentrations in the fetus. The objective of this study was to determine if changes in placental 5αR were associated with neonatal outcome after birth. Guinea pigs were delivered by cesarean section at term (GA69, n=22) or preterm (GA62, n=36) and the placenta collected. Preterm neonates were maintained for 24 h unless their condition deteriorated before this time. Enzyme mRNA expression of 5αR type-1 and 5αR type-2 were determined using real-time PCR. All preterm neonates had significantly higher 5αR2 expression in their placenta compared with placentae from term neonates (P<0.0001). Expression was also markedly higher in the placentae from neonates that did not survive until 24 h, compared with surviving preterm neonates (P=0.04). These findings suggest differences of in utero neurosteroidogenic capacity between surviving and non-surviving preterm guinea pig neonates. The increased 5αR2 mRNA expression in the placenta of non-survivors suggests an induction of the neurosteroid pathway due to prior exposure to an in utero compromise, with such exposure possibly a predisposing factor that contributed to their poor ex utero outcome.

Allopregnanolone and social stress: regulation of the stress response in early pregnancy in pigs

This experiment investigated whether allopregnanolone, a neurosteroid metabolite from progesterone, modulates the stress response during early pregnancy. Twenty-five nulliparous sows (Sus scrofa) were allocated to one of three treatments: pregnant, ovariectomized or ovariectomized administered daily intravenously with alfaxalone as a synthetic allopregnanolone analog. On days 5, 12 and 19 of pregnancy, all sows were subjected to social stress by submitting them individually to a resident-intruder test, acting as the intruder. Blood samples were collected to analyze plasma progesterone, allopregnanolone, cortisol and adrenocorticotropic hormone (ACTH) concentrations. On day 26, 10 sows across the three treatments were subjected to a dexamethasone suppression test followed by a corticotrophin-releasing hormone administration to test the functionality of their hypothalamo-pituitary-adrenal (HPA) axis through cortisol release. Pregnant sows returned more rapidly to baseline cortisol concentrations following the resident-intruder test (p = 0.006). However, there were no other differences in cortisol or ACTH concentrations according to treatment or day, or to the HPA responsivity test on day 26. Allopregnanolone concentration in pregnant sows was higher than in ovariectomized sows (p < 0.001), but stable during the first third of pregnancy. Allopregnanolone concentration was correlated with longer resident-intruder test duration (pregnant: r = 0.66, p = 0.0003; ovariectomized: r = 0.47, p = 0.03), reflecting lower aggressiveness, and with progesterone concentration (r = 0.25, p = 0.03). Alfaxalone administration raised plasma allopregnanolone concentration in alfaxalone-administered sows but resulted in little behavioral and physiological effects. These findings did not support the hypothesis that the stress response of the female pig changes in the first third of pregnancy. Allopregnanolone was associated with lower aggression in social encounters.

Decreased allopregnanolone induced by hormonal contraceptives is associated with a reduction in social behavior and sexual motivation in female rats

RATIONALE

Allopregnanolone is a neurosteroid involved in depression, memory, social, and sexual behavior. We have previously demonstrated that treatment with a combination of ethinylestradiol (EE) and levonorgestrel (LNG), two compounds frequently used in hormonal contraception, decreased brain allopregnanolone concentrations. These changes may contribute to some of the emotional and sexual disorders observed in hormonal contraceptive users.

OBJECTIVES

We thus examined whether the reduction in allopregnanolone concentrations induced by long-term EE/LNG administration was associated with altered emotional, learning, social, and sexual behaviors.

METHODS

Rats were orally treated with a combination of EE (0.030 mg) and LNG (0.125 mg) once a day for 4 weeks and were subjected to behavioral tests 24 h after the last administration.

RESULTS

EE/LNG treatment reduced immobility behavior in the forced swim test, without affecting sucrose preference and spatial learning and memory. In the resident-intruder test, EE/LNG-treated rats displayed a decrease in dominant behaviors associated with a reduction in social investigation. In the paced mating test, EE/LNG treated rats showed a reduction in proceptive behaviors, while the lordosis quotient was not affected. Progesterone, but not estradiol, administration to EE/LNG-treated rats increased sexual activity and cerebrocortical allopregnanolone concentrations. Prior administration of finasteride decreased allopregnanolone concentrations and abolished the increase in proceptivity induced by progesterone administration.

CONCLUSIONS

The decrease in brain allopregnanolone concentrations induced by EE/LNG treatment is associated with a reduction in social behavior and sexual motivation in female rats. These results might be relevant to the side effects sometimes exhibited by women taking hormonal contraceptives.