The impact of pubertal stress and adult hormone exposure on the transcriptome of the developing hypothalamus.

Why individuals suffer negative consequences following stress is a complex phenomenon that is dictated by individual factors, the timing of stress within the lifespan, and when in the lifespan the consequences are measured. Women who undergo adverse childhood experiences are at risk for lasting biological consequences, including affective and stress dysregulation. We have shown that pubertal adversity is associated with a blunted hypothalamic-pituitary-adrenal axis glucocorticoid response in peripartum humans and mice. In mice, our prior examination of the paraventricular nucleus (PVN) of the hypothalamus showed that pubertal stress led to an upregulation of baseline mRNA expression of six immediate early genes (IEGs) in the PVN of adult, pregnant mice. Separately, we showed that the pregnancy-associated hormone allopregnanolone is necessary and sufficient to produce the blunted stress response phenotype in pubertally stressed mice. In the current study, we further examined a potential mechanistic role for the IEGs in the PVN. We found that in pubertally stressed adult female, but not male, mice, intra-PVN allopregnanolone was sufficient to recapitulate the baseline IEG mRNA expression profile previously observed in pubertally stressed, pregnant mice. We also examined baseline IEG mRNA expression during adolescence, where we found that IEGs have developmental trajectories that showed sex-specific disruption by pubertal stress. Altogether, these data establish that IEGs may act as a key molecular switch involved in increased vulnerability to negative outcomes in adult, pubertally stressed animals. How the factors that produce vulnerability combine throughout the lifespan is key to our understanding of the etiology of stress-related disorders.

Allopregnanolone and its antagonist modulate neuroinflammation and neurological impairment.

Neuroinflammation accompanies several brain disorders, either as a secondary consequence or as a primary cause and may contribute importantly to disease pathogenesis. Neurosteroids which act as Positive Steroid Allosteric GABA-A receptor Modulators (Steroid-PAM) appear to modulate neuroinflammation and their levels in the brain may vary because of increased or decreased local production or import from the systemic circulation. The increased synthesis of steroid-PAMs is possibly due to increased expression of the mitochondrial cholesterol transporting protein (TSPO) in neuroinflammatory tissue, and reduced production may be due to changes in the enzymatic activity. Microglia and astrocytes play an important role in neuroinflammation, and their production of inflammatory mediators can be both activated and inhibited by steroid-PAMs and GABA. What is surprising is the finding that both allopregnanolone, a steroid-PAM, and golexanolone, a novel GABA-A receptor modulating steroid antagonist (GAMSA), can inhibit microglia and astrocyte activation and normalize their function. This review focuses on the role of steroid-PAMs in neuroinflammation and their importance in new therapeutic approaches to CNS and liver disease.

Neurosteroid Modulation of Synaptic and Extrasynaptic GABAA Receptors of the Mouse Nucleus Accumbens.

The recent approval of formulations of the endogenous neurosteroid allopregnanolone (brexanolone) and the synthetic neuroactive steroid SAGE-217 (zuranolone) to treat postpartum depression (PPD) has encouraged further research to elucidate why these potent enhancers of GABAAR function are clinically effective in this condition. Dopaminergic projections from the ventral tegmental area (VTA) to the nucleus accumbens are associated with reward/motivation and brain imaging studies report that individuals with PPD show reduced activity of this pathway in response to reward and infant engagement. However, the influence of neurosteroids on GABA-ergic transmission in the nucleus accumbens has received limited attention. Here, we investigate, in the medium spiny neurons (MSNs) of the mouse nucleus accumbens core, the effect of allopregnanolone, SAGE-217 and other endogenous and synthetic steroids of interest on fast phasic and tonic inhibition mediated by synaptic (α1/2ßγ2) and extrasynaptic (α4ßδ) GABAARs, respectively. We present evidence suggesting the resident tonic current results from the spontaneous opening of δ-GABAARs, where the steroid-enhanced tonic current is GABA-dependent. Furthermore, we demonstrate local neurosteroid synthesis in the accumbal slice preparation and reveal that GABA-ergic neurotransmission of MSNs is influenced by an endogenous neurosteroid tone. Given the dramatic fluctuations in allopregnanolone levels during pregnancy and postpartum, this neurosteroid-mediated local fine-tuning of GABAergic transmission in the MSNs will probably be perturbed.

Impact of NMDA receptors block versus GABA-A receptors modulation on synaptic plasticity and brain electrical activity in metabolic syndrome.

PURPOSE: Metabolic syndrome (MetS) is a common disorder associated with disturbed neurotransmitter homeostasis. Memantine, an N-methyl-d-aspartate receptor (NMDAR) antagonist, was first used in Alzheimer's disease. Allopregnanolone (Allo), a potent positive allosteric modulator of the Gamma-Amino-Butyric Acid (GABA)-A receptors, decreases in neurodegenerative diseases. The study investigated the impact of Memantine versus Allo administration on the animal model of MetS to clarify whether the mechanism of abnormalities is related more to excitatory or inhibitory neurotransmitter dysfunction. MATERIALS AND METHODS: Fifty-six male rats were allocated into 7 groups: 4 control groups, 1 MetS group, and 2 treated MetS groups. They underwent assessment of cognition-related behavior by open field and forced swimming tests, electroencephalogram (EEG) recording, serum markers confirming the establishment of MetS model and hippocampal Glial Fibrillary Acidic Protein (GFAP) and Brain-Derived Neurotrophic Factor (BDNF). RESULTS: Allo improved anxiety-like behavior and decreased grooming frequency compared to Memantine. Both drugs increased GFAP and BDNF expression, improving synaptic plasticity and cognition-related behaviors. The therapeutic effect of Allo was more beneficial regarding lipid profile and anxiety. We reported progressive slowing of EEG waves in the MetS group with Memantine and Allo treatment with increased relative theta and decreased relative delta rhythms. CONCLUSIONS: Both Allo and Memantine boosted the outcome parameters in the animal model of MetS. Allo markedly improved the anxiety-like behavior in the form of significantly decreased grooming frequency compared to the Memantine-treated groups. Both drugs were associated with increased hippocampal GFAP and BDNF expression, indicating an improvement in synaptic plasticity and so, cognition-related behaviors.

Witnessed trauma exposure induces fear in mice through a reduction in endogenous neurosteroid synthesis.

Neurosteroids have been implicated in the pathophysiology of post-traumatic stress disorder (PTSD). Allopregnanolone is reduced in subsets of individuals with PTSD and has been explored as a novel treatment strategy. Both direct trauma exposure and witnessed trauma are risk factors for PTSD; however, the role of neurosteroids in the behavioral outcomes of these unique experiences has not been explored. Here, we investigate whether observational fear is associated with a reduced capacity for endogenous neurosteroidogenesis and the relationship with behavioral outcomes. We demonstrated that mice directly subjected to a threat (foot shocks) and those witnessing the threat have decreased plasma levels of allopregnanolone. The expression of a key enzyme involved in endogenous neurosteroid synthesis, 5α-reductase type 2, is decreased in the basolateral amygdala, which is a major emotional processing hub implicated in PTSD. We demonstrated that genetic knockdown or pharmacological inhibition of 5α-reductase type 2 exaggerates the behavioral expression of fear in response to witnessed trauma, whereas oral treatment with an exogenous, synthetic neuroactive steroid gamma-aminobutyric acid-A receptor positive allosteric modulator with molecular pharmacology similar to allopregnanolone (SGE-516 [tool compound]) decreased the behavioral response to observational fear. These data implicate impaired endogenous neurosteroidogenesis in the pathophysiology of threat exposure, both direct and witnessed. Further, these data suggest that treatment with exogenous 5α-reduced neurosteroids or targeting endogenous neurosteroidogenesis may be beneficial for the treatment of individuals with PTSD, whether resulting from direct or witnessed trauma.

Indirect comparisons of relative efficacy estimates of zuranolone and selective serotonin reuptake inhibitors for postpartum depression.

AIMS: Estimate relative efficacy of zuranolone, a novel oral, Food and Drug Administration-approved treatment for postpartum depression (PPD) in adults vs. selective serotonin reuptake inhibitors (SSRIs) and combination therapies used for PPD in the United States. MATERIALS AND METHODS: Randomized controlled trials (RCTs) for zuranolone and SSRIs, identified from systematic review, were used to construct evidence networks, linking via common comparator arms. Due to heterogeneity in placebo responses, matching-adjusted indirect comparison (MAIC) was applied, statistically weighting the zuranolone treatment arm of Phase 3 SKYLARK Study (NCT04442503) to the placebo arm of RCTs investigating SSRIs for PPD. MAIC outputs were applied in Bucher indirect treatment comparisons (ITCs) and network meta-analysis (NMA), using Edinburgh Postnatal Depression Scale (EPDS) and 17-item Hamilton Rating Scale for Depression (HAMD-17) change from baseline (CFB) on Days 3, 15, 28 (Month 1), 45, and last observation (Day 45, Week 12/18). RESULTS: Larger EPDS CFB was observed among zuranolone-treated vs. SSRI-treated patients from Day 15 onward. Zuranolone-treated (vs. SSRI-treated) patients exhibited 4.22-point larger reduction in EPDS by Day 15 (95% confidence interval: -6.16, -2.28) and 7.43-point larger reduction at Day 45 (-9.84, -5.02) with Bucher ITC. NMA showed EPDS reduction for zuranolone was 4.52 (-6.40, -2.65) points larger than SSRIs by Day 15 and 7.16 (-9.47, -4.85) larger at Day 45. Lack of overlap between study populations substantially reduced effective sample size post-matching, making HAMD-17 CFB analysis infeasible. LIMITATIONS: Limited population overlap between SKYLARK Study and RCTs reduced feasibility of undertaking HAMD-17 CFB ITCs and may introduce uncertainty to EPDS CFB ITC results. CONCLUSIONS: Analysis showed zuranolone-treated patients with PPD experienced greater symptom improvement than SSRI-treated patients from Day 15 onward, with largest mean difference at Day 45. Adjusting for differences between placebo arms, zuranolone may be associated with greater PPD symptom improvement (measured by EPDS) vs. SSRIs.

Different dosage regimens of zuranolone in the treatment of major depressive disorder: A meta-analysis of randomized controlled trials.

OBJECTIVE: To investigate the efficacy and safety of different dosage regimens of zuranolone in the treatment of patients with major depressive disorder (MDD). METHODS: PubMed, Embase, The Cochrane Library and other databases were searched from inception until July 2019. Randomized controlled trials (RCTs) related to the efficacy and safety of zuranolone in the treatment of MDD were included. The data were extracted independently by 2 investigators and assessed the study quality by the Cochrane risk-of-bias tool. The primary outcome includes the 17-item HAMILTON total score (HAMD-17) and the incidence of adverse events (AEs). RESULTS: Six high-quality RCTs with 1593 patients were finally included in our analysis. Zuranolone group achieve a notable treatment effect at day15 in HAMD-17 compared with placebo group (MD = -2.69, 95 % CI: -4.45 to -0.94, P < 0.05). For safety, no significant differences existed in the proportion of patients with AEs between zuranolone with placebo (RR = 1.25, 95 % CI: 0.99 to 1.58, P = 0.06). CONCLUSION: Zuranolone has a significant efficacy in improving depressive symptoms in the short term and is positively correlated with the dosage administered. However, the efficacy of zuranolone decreased significantly when the time of administration was extended. Zuranolone demonstrated a controllable safety issue. But adverse effects increased as the dose of zuranolone was gradually increased to 50 mg.

Involvement of the GABAA Receptor in the Antidepressant-Like Effects Produced by Low and High Doses of the Flavonoid Chrysin in the Rat: A Longitudinal Study.

BACKGROUND: The flavonoid chrysin produces rapid and long-lasting anxiolytic- and antidepressant-like effects in rats. However, it is not known whether low and high doses of chrysin produce differential anti-immobility effects through the Gamma-Aminobutyric Acid sub-type A (GABAA) receptor. The goal of this work was therefore to compare low and high doses of chrysin for their effects on depression-like behavior in a longitudinal study. Moreover, chrysin was compared with the serotonergic fluoxetine and Gamma-Aminobutyric Acid (GABA)ergic allopregnanolone, and its involvement with the GABAA receptor after chronic treatment was also investigated. METHODS: Male Wistar rats were assigned to five groups (n = 8 each): vehicle, 1 mg/kg chrysin, 5 mg/kg chrysin, 1 mg/kg fluoxetine, and 1 mg/kg allopregnanolone. In the first experiment, treatments were injected daily and the effects on locomotor activity and the forced swim test were evaluated at 0, 1, 14, and 28 days of treatment, and 48 h after the final treatment. In the second experiment, similar groups were treated for 28 days with injection of 1 mg/kg picrotoxin to investigate the role of the GABAA receptor. Depending on the experimental design, one- and two-way analysis of variance (ANOVA) tests were used for statistical analysis, with p < 0.05 set as the criteria for significance. RESULTS: In both experiments, the treatments did not alter locomotor activity. However, low and high doses of chrysin, allopregnanolone, and fluoxetine gradually produced antidepressant-like effects in the forced swim test, and maintained this effect for 48 h post-treatment, except with low dose chrysin. Picrotoxin blocked the antidepressant-like effects produced by low dose chrysin, but did not affect those produced by high dose chrysin, allopregnanolone, or fluoxetine. CONCLUSIONS: The differential antidepressant-like effects caused by low and high doses of chrysin are time-dependent. Low dose chrysin produces a rapid antidepressant-like effect, whereas high dose chrysin produces a delayed but sustained the effect, even 48 h after withdrawal. The effect with high dose chrysin was similar to that observed with allopregnanolone and fluoxetine. The mechanism for the antidepressant-like effect of low chrysin appears to be GABAergic, whereas the effect of high dose chrysin may involve other neurotransmission and neuromodulation systems related to the serotonergic system.

The cost-effectiveness of zuranolone versus selective serotonin reuptake inhibitors for the treatment of postpartum depression in the United States.

AIMS: The objective of this research is to evaluate the cost-effectiveness of zuranolone, the first oral treatment indicated for postpartum depression (PPD) in adults approved by the United States Food and Drug Administration. METHODS: Zuranolone and selective serotonin reuptake inhibitor (SSRI) trial-based efficacy was derived from an indirect treatment comparison. Long-term efficacy outcomes were based on a large longitudinal cohort study. Maternal health utility values were derived from trial-based, short-form 6-D responses. Other inputs were derived from literature and economic data from the US Bureau of Labor Statistics. We estimated costs (2023 US dollars) and quality-adjusted life-years (QALYs) for patients with PPD treated with zuranolone (14-day dosing) or SSRIs (chronic dosing). The indirect costs and QALYs of the children and partners were also estimated. RESULTS: The incremental cost-effectiveness ratio for zuranolone versus SSRIs was $94,741 per QALY gained over an 11-year time horizon. Maternal total direct medical costs averaged $84,318 in the zuranolone arm, compared to $86,365 in the SSRI arm. Zuranolone-treated adults averaged 6.178 QALYs compared to 6.116 QALYs for the SSRI arm. Costs and utilities for the child and partner were also included in the base case. Drug and administration costs for zuranolone averaged $15,902, compared to $30 for SSRIs over the studied time horizon. Results were sensitive to the model time horizon. LIMITATIONS: As head-to-head trials were not available to permit direct comparison, efficacy inputs were derived from an indirect treatment comparison which can be confounded by cross-trial differences. The data used are reflective of a general PPD population rather than marginalized individuals who may be at a greater risk for adverse PPD outcomes. The model likely excludes unmeasured effects for patient, child, and partner. CONCLUSIONS: This economic model's results suggest that zuranolone is a more cost-effective therapy compared to SSRIs for treating adults with PPD.

QUESTION: Is zuranolone cost-effective compared to selective serotonin-reuptake inhibitors for the treatment of postpartum depression (PPD) in adults in a United States (US) health care setting? FINDINGS: The model, which incorporated clinical trial data, long-term longitudinal cohort data, US Bureau of Labor Statistics data on compensation, and other peer-reviewed literature, projects that zuranolone is cost-effective compared to selective serotonin-reuptake inhibitors for the treatment of PPD at a willingness-to-pay threshold of $150,000 (USD).Meaning: For adults with PPD requiring pharmacological intervention, zuranolone may be a cost-effective treatment option with the potential to confer quality-of-life benefits for these patients and their families as well as economic benefits for society.

The role of neuroactive steroids in tic disorders.

Tics are sudden, repetitive movements or vocalizations. Tic disorders, such as Tourette syndrome (TS), are contributed by the interplay of genetic risk factors and environmental variables, leading to abnormalities in the functioning of the cortico-striatal-thalamo-cortical (CSTC) circuitry. Various neurotransmitter systems, such as gamma-aminobutyric acid (GABA) and dopamine, are implicated in the pathophysiology of these disorders. Building on the evidence that tic disorders are predominant in males and exacerbated by stress, emerging research is focusing on the involvement of neuroactive steroids, including dehydroepiandrosterone sulfate (DHEAS) and allopregnanolone, in the ontogeny of tics and other phenotypes associated with TS. Emerging evidence indicates that DHEAS levels are significantly elevated in the plasma of TS-affected boys, and the clinical onset of this disorder coincides with the period of adrenarche, the developmental stage characterized by a surge in DHEAS synthesis. On the other hand, allopregnanolone has garnered particular attention for its potential to mediate the adverse effects of acute stress on the exacerbation of tic severity and frequency. Notably, both neurosteroids act as key modulators of GABA-A receptors, suggesting a pivotal role of these targets in the pathophysiology of various clinical manifestations of tic disorders. This review explores the potential mechanisms by which these and other neuroactive steroids may influence tic disorders and discusses the emerging therapeutic strategies that target neuroactive steroids for the management of tic disorders.

Local effect of allopregnanolone in rat ovarian steroidogenesis, follicular and corpora lutea development.

Allopregnanolone (ALLO) is a known neurosteroid and a progesterone metabolite synthesized in the ovary, CNS, PNS, adrenals and placenta. Its role in the neuroendocrine control of ovarian physiology has been studied, but its in situ ovarian effects are still largely unknown. The aims of this work were to characterize the effects of intrabursal ALLO administration on different ovarian parameters, and the probable mechanism of action. ALLO administration increased serum progesterone concentration and ovarian 3ß-HSD2 while decreasing 20α-HSD mRNA expression. ALLO increased the number of atretic follicles and the number of positive TUNEL granulosa and theca cells, while decreasing positive PCNA immunostaining. On the other hand, there was an increase in corpora lutea diameter and PCNA immunostaining, whereas the count of TUNEL-positive luteal cells decreased. Ovarian angiogenesis and the immunohistochemical expression of GABAA receptor increased after ALLO treatment. To evaluate if the ovarian GABAA receptor was involved in these effects, we conducted a functional experiment with a specific antagonist, bicuculline. The administration of bicuculline restored the number of atretic follicles and the diameter of corpora lutea to normal values. These results show the actions of ALLO on the ovarian physiology of the female rat during the follicular phase, some of them through the GABAA receptor. Intrabursal ALLO administration alters several processes of the ovarian morpho-physiology of the female rat, related to fertility and oocyte quality.

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.

Brexanolone Treatment in a Real-World Patient Population: A Case Series and Pilot Feasibility Study of Precision Neuroimaging.

PURPOSE/BACKGROUND: Brexanolone is approved for postpartum depression (PPD) by the United States Food and Drug Administration. Brexanolone has outperformed placebo in clinical trials, but less is known about the efficacy in real-world patients with complex social and medical histories. Furthermore, the impact of brexanolone on large-scale brain systems such as changes in functional connectivity (FC) is unknown. METHODS/PROCEDURES: We tracked changes in depressive symptoms across a diverse group of patients who received brexanolone at a large medical center. Edinburgh Postnatal Depression Scale (EPDS) scores were collected through chart review for 17 patients immediately prior to infusion through approximately 1 year postinfusion. In 2 participants, we performed precision functional neuroimaging (pfMRI), including before and after treatment in 1 patient. pfMRI collects many hours of data in individuals for precision medicine applications and was performed to assess the feasibility of investigating changes in FC with brexanolone. FINDINGS/RESULTS: The mean EPDS score immediately postinfusion was significantly lower than the mean preinfusion score (mean change [95% CI]: 10.76 [7.11-14.40], t (15) = 6.29, P < 0.0001). The mean EPDS score stayed significantly lower at 1 week (mean difference [95% CI]: 9.50 [5.23-13.76], t (11) = 4.90, P = 0.0005) and 3 months (mean difference [95% CI]: 9.99 [4.71-15.27], t (6) = 4.63, P = 0.0036) postinfusion. Widespread changes in FC followed infusion, which correlated with EPDS scores. IMPLICATIONS/CONCLUSIONS: Brexanolone is a successful treatment for PPD in the clinical setting. In conjunction with routine clinical care, brexanolone was linked to a reduction in symptoms lasting at least 3 months. pfMRI is feasible in postpartum patients receiving brexanolone and has the potential to elucidate individual-specific mechanisms of action.

Zuranolone, a neuroactive drug, used in the treatment of postpartum depression by modulation of GABAA receptors.

BACKGROUND: Postpartum depression [PPD] is a prevalent and debilitating mood disorder that affects mothers in the weeks to months after childbirth. Zuranolone (Zurzuvae) is a novel pharmaceutical agent that was approved by the US FDA on 4 August 2023 for the management of PPD. This review article provides a comprehensive overview of zuranolone, focusing on its dosing, chemistry, mechanism of action, clinical trials, adverse drug reaction, and overall conclusion regarding its utility in the management of PPD. It also discusses the recommended dosing strategies to achieve optimal efficacy while minimizing adverse effects as the dosage regimen of zuranolone is critical for its therapeutic application. Moreover, it gives insights into neurobiological pathways involved in PPD. METHODOLOGY: Data from randomized controlled trials and observational studies was collected to provide a comprehensive understanding of zuranolone in the management and treatment of PPD. CONCLUSION: Zuranolone represents a promising therapeutic option for women suffering from postpartum depression. However, ongoing research and post-marketing surveillance are essential to further elucidate its long-term safety and efficacy. The integration of zuranolone into clinical practice may significantly improve the quality of life for mothers facing the challenges of postpartum depression.

Exploring the clinical potentials of zuranolone in managing postpartum depression: A new therapeutic horizon.

Postpartum depression (PPD) poses a major threat to maternal mental health and wellbeing while also adversely affecting the mother's relationship with her baby, leading to significant repercussions that may hinder the growth and cognitive development of the child. For decades, antidepressants have been the mainstay of treating PPD; however, recent evidence suggests that antidepressants are not as effective as they are believed to be and there is a dire need to explore new treatment options. In 2023, a breakthrough in treating PPD emerged with the recent FDA approval of zuranolone, a gamma-aminobutyric acid (GABAA) receptor selective positive allosteric modulator. The implementation of zuranolone in treating PPD can prove to be revolutionary, considering it is the first oral medication available for PPD. Our review aims to discuss the various clinical trials that have been conducted to validate the efficacy of zuranolone in mitigating the symptoms of PPD, hence, leading to better outcomes for mothers.

Cardiovascular responses of adult male Sprague-Dawley rats following acute organophosphate intoxication and post-exposure treatment with midazolam with or without allopregnanolone.

Recent experimental evidence suggests combined treatment with midazolam and allopregnanolone is more effective than midazolam alone in terminating seizures triggered by acute organophosphate (OP) intoxication. However, there are concerns that combined midazolam and allopregnanolone increases risk of adverse cardiovascular events. To address this, we used telemetry devices to record cardiovascular responses in adult male Sprague-Dawley rats acutely intoxicated with diisopropylfluorophosphate (DFP). Animals were administered DFP (4 mg/kg, sc), followed immediately by atropine (2 mg/kg, i.m.) and 2-PAM (25 mg/kg, i.m.). At 40 min post-exposure, a subset of animals received midazolam (0.65 mg/kg, im); at 50 min, these rats received a second dose of midazolam or allopregnanolone (12 mg/kg, im). DFP significantly increased blood pressure by ~ 80 mmHg and pulse pressure by ~ 34 mmHg that peaked within 12 min. DFP also increased core temperature by ~ 3.5 °C and heart rate by ~ 250 bpm that peaked at ~ 2 h. Heart rate variability (HRV), an index of autonomic function, was reduced by ~ 80%. All acute (within 15 min of exposure) and two-thirds of delayed (hours after exposure) mortalities were associated with non-ventricular cardiac events within 10 min of cardiovascular collapse, suggesting that non-ventricular events should be closely monitored in OP-poisoned patients. Compared to rats that survived DFP intoxication without treatment, midazolam significantly improved recovery of cardiovascular parameters and HRV, an effect enhanced by allopregnanolone. These data demonstrate that midazolam improved recovery of cardiovascular and autonomic function and that the combination of midazolam and allopregnanolone may be a better therapeutic strategy than midazolam alone.

Factors promoting the release of picrotoxin from the trap in the GABA(A) receptor pore.

Picrotoxin (PTX), a convulsant of plant origin, has been used in many studies as research tool. PTX is the open channel blocker of the GABAA receptor (GABAAR). Being in the pore, PTX initiates transfer of the channel to the closed state and thus it falls into the "trap". The consequence of this PTX trapping is so-called aftereffect, i.e. continuation of the blockade of the GABA-induced chloride current (IGABA) after removal of PTX from the external solution. The present work shows that the positive allosteric modulators (PAMs) of the GABAA receptor, allopregnanolone (Allo) and zolpidem (Zolp) as well as a high concentration of GABA shortened the PTX aftereffect. Experiments were carried out on isolated Purkinje neurons of the rat cerebellum using the whole-cell patch-clamp method. IGABA was induced by applications of 5 µM GABA (EC30) for 1 s with 30 s intervals. 50 µM PTX completely blocked IGABA, and recovery upon PTX washout occurred with a time constant (τrec) of 20.2 min. 1 µM Allo reduced the blocking effect of PTX by 30% and accelerated the recovery of IGABA by almost 10 times (τrec = 2.4 min). 0.5 µM Zolp did not change the IGABA block in the presence of PTX but accelerated the recovery of IGABA by more than 3 times (τrec = 5.6 min). Increasing the GABA concentration to 20 µM did not change the blocking effect of PTX, but accelerated recovery by 6 times (τrec = 3.3 min). The mechanism of the shortening of the PTX aftereffect is presumably the expansion of the GABAAR pore in the presence of PAMs and a high concentration of the agonist and, as a consequence, the escape of PTX from the "trap". The work describes new pharmacological properties of Allo and Zolp.

The magnitude and sustainability of treatment benefit of zuranolone on function and well-being as assessed by the SF-36 in adult patients with MDD and PPD: An integrated analysis of 4 randomized clinical trials.

BACKGROUND: Major depressive disorder (MDD) and postpartum depression (PPD) are disabling conditions. This integrated analysis of MDD and PPD clinical trials investigated the impact of zuranolone-a positive allosteric modulator of synaptic and extrasynaptic GABAA receptors and neuroactive steroid under investigation for adults with MDD and approved as an oral, once-daily, 14-day treatment course for adults with PPD in the US-on health-related quality of life, including functioning and well-being, as assessed using the 36-item Short Form Health Survey V2 (SF-36). METHODS: Integrated data from 3 MDD (201B, MOUNTAIN, WATERFALL) and 1 PPD trial (ROBIN) for individual SF-36 domains were compared for zuranolone (30- and 50-mg) vs placebo at Day (D)15 and D42. Comparisons between zuranolone responders (≥50 % reduction from baseline in 17-item Hamilton Depression Rating Scale total score) and nonresponders were assessed. RESULTS: Overall, 1003 patients were included (zuranolone, n = 504; placebo, n = 499). Significant differences in change from baseline (CFB) to D15 for patients in zuranolone vs placebo groups were observed in 6/8 domains; changes were sustained or improved at D42, with significant CFB differences for all 8 domains. Zuranolone responders had significantly higher CFB scores vs nonresponders for all domains at D15 and D42 (p < 0.001). LIMITATIONS: Two zuranolone doses were integrated across populations of 2 disease states with potential differences in functioning, comorbidities, and patient demographics. All p-values presented are nominal. CONCLUSIONS: Integrated data across 4 zuranolone clinical trials showed improvements in functioning and well-being across all SF-36 domains. Benefits persisted after completion of treatment course at D42.

Neurosteroids and their potential as a safer class of general anesthetics.

Neurosteroids (NS) are a class of steroids that are synthesized within the central nervous system (CNS). Various NS can either enhance or inhibit CNS excitability and they play important biological roles in brain development, brain function and as mediators of mood. One class of NS, 3α-hydroxy-pregnane steroids such as allopregnanolone (AlloP) or pregnanolone (Preg), inhibits neuronal excitability; these endogenous NS and their analogues have been therapeutically applied as anti-depressants, anti-epileptics and general anesthetics. While NS have many favorable properties as anesthetics (e.g. rapid onset, rapid recovery, minimal cardiorespiratory depression, neuroprotection), they are not currently in clinical use, largely due to problems with formulation. Recent advances in understanding NS mechanisms of action and improved formulations have rekindled interest in development of NS as sedatives and anesthetics. In this review, the synthesis of NS, and their mechanism of action will be reviewed with specific emphasis on their binding sites and actions on γ-aminobutyric acid type A (GABAA) receptors. The potential advantages of NS analogues as sedative and anesthetic agents will be discussed.