Antidepressant effects of esketamine via the BDNF/AKT/mTOR pathway in mice with postpartum depression and their offspring.

Postpartum depression (PPD) is a serious mental health problem that can negatively affect future generations. BDNF/AKT/mTOR signaling in the frontal lobe and hippocampus in mice is associated with depression, but its role in mice with PPD and their offspring is unknown. This study was aimed at investigating the effects of esketamine (ESK), a drug approved for treatment of refractory depression, on the BDNF/AKT/mTOR pathway in mice with PPD and their offspring. A model of chronic unpredictable mild stress with pregnancy was used. ESK was injected into postpartum mice, and behavioral tests were conducted to predict the severity of symptoms at the end of lactation and in the offspring after adulthood. Both mice with PPD and their offspring showed significant anxiety- and depression-like behaviors that were ameliorated with the ESK intervention. ESK enhanced exploratory behavior in unfamiliar environments, increased the preference for sucrose, and ameliorated the impaired BDNF/AKT/mTOR signaling in the frontal and hippocampal regions in mice. Thus, ESK may have great potential in treating PPD and decreasing the incidence of depression in offspring.

Postpartum symptoms of anxiety, depression and stress: differential relationships to women's cortisol profiles.

PURPOSE: Women are at high risk of stress, anxiety, and depression during the postpartum but the ways in which these different types of psychological distress are related to cortisol regulation is not clear. We examined the distinct association of each type of distress with women's average cortisol level, cortisol awakening response (CAR), cortisol decline across the day (diurnal slope), and overall amount of cortisol secretion across the day (AUCG). METHODS: At 6 months postpartum, a diverse group of 58 women completed measures of depression, anxiety, perceived stress, and life stressors. Each woman provided 4 salivary samples for cortisol assay from waking to bedtime on each of 2 consecutive days. Linear regressions were used to examine associations of stress, anxiety and depression to each of the 4 cortisol measures, controlling for number of stressful life events. RESULTS: Depressive symptoms were associated with less of a rise in the CAR (ß = -.46, p = 0.01), steeper diurnal slope (ß = .51, p = 0.006), and higher average cortisol level (ß = .42, p = .01). Women who met the clinical cutoff for an anxiety disorder had lower overall cortisol output (ß = -.29, p = 0.03). Stress was not related to any cortisol metric. CONCLUSIONS: Findings suggest that stress is less associated with cortisol alterations in the postpartum than are more severe types of psychological distress. Anxiety and depression may have distinct and opposite profiles of cortisol dysregulation. Results indicate that mental health assessment is critical even in the later postpartum so that interventions can be initiated to reduce emotional suffering and the risk of impaired cortisol regulation.

TOM40 mediates the effect of TSPO on postpartum depression partially through regulating calcium homeostasis in microglia.

AIMS: To assess the effect of the translocator protein 18 kDa (TSPO) on postpartum depression and explore its mechanism. METHODS: Postpartum depression (PPD) mouse model was established, and flow cytometry, immunofluorescence, Western blot analysis, real-time quantitative PCR, adeno-associated virus (AAV), co-immunoprecipitation-mass spectrometry and immunofluorescence co-staining were used to detect the effect of TSPO ligand ZBD-2 on PPD mice. RESULTS: ZBD-2 inhibits the overactivation of microglia in the hippocampus and amygdala of PPD model mice. ZBD-2 not only inhibited the inflammation but also repressed the burst of reactive oxygen species (ROS) and mitochondrial ROS (mtROS). Meanwhile, ZBD-2 protects mitochondria from LPS-induced damages through inhibiting the influx of calcium. ZBD-2 modulated the calcium influx by increasing the level of translocase of the outer mitochondrial membrane 40 (TOM40) and reducing the interaction of TSPO and TOM40. In addition, the effect of ZBD-2 was partially dependent on anti-oxidative process. Knockdown of TOM40 by adeno-associated virus (AAV) in the hippocampus or amygdala dramatically reduced the effect of ZBD-2 on PPD, indicating that TOM40 mediates the effect of ZBD-2 on PPD. CONCLUSIONS: TOM40 is required for the effect of ZBD-2 on treating anxiety and depression in PPD mice. This study reveals the role of microglia TSPO in PPD development and provides the new therapeutic strategy for PPD.

Divergent Transcriptomic Effects of Allopregnanolone in Postpartum Depression.

Brexanolone, a formulation of the neurosteroid allopregnanolone (ALLO), is approved for treating postpartum depression (PPD) and is being investigated for therapeutic efficacy across numerous neuropsychiatric disorders. Given ALLO's beneficial effects on mood in women with PPD compared to healthy control women, we sought to characterize and compare the cellular response to ALLO in women with (n = 9) or without (n = 10, i.e., Controls) past PPD, utilizing our previously established patient-derived lymphoblastoid cell lines (LCLs). To mimic in vivo PPD ALLO-treatment, LCLs were exposed to ALLO or DMSO vehicle for 60 h and RNA-sequenced to detect differentially expressed genes (DEGs, pnominal < 0.05). Between ALLO-treated Control and PPD LCLs, 269 DEGs were identified, including Glutamate Decarboxylase 1 (GAD1), which was decreased 2-fold in PPD. Network analysis of PPD:ALLO DEGs revealed enriched terms related to synaptic activity and cholesterol biosynthesis. Within-diagnosis analyses (i.e., DMSO vs. ALLO) detected 265 ALLO-induced DEGs in Control LCLs compared to only 98 within PPD LCLs, with just 11 DEGs overlapping. Likewise, the gene ontologies underlying ALLO-induced DEGs in PPD and Control LCLs were divergent. These data suggest that ALLO may activate unique and opposing molecular pathways in women with PPD, which may be tied to its antidepressant mechanism.

Intrinsically dysregulated cellular stress signaling genes and gene networks in postpartum depression.

Postpartum depression (PPD) is a leading cause of morbidity and mortality among women. Clinically, the administration and withdrawal of supraphysiologic estradiol and progesterone (E2 + P) can cause affective symptom reoccurrence in women with a history of PPD, but not matched controls. To investigate the cellular basis underlying this differential affective response, lymphoblastoid cell lines (LCLs) were derived from women with and without past PPD and compared transcriptomically in hormone conditions mimicking pregnancy and parturition: supraphysiologic E2 + P-addback; supraphysiologic E2 + P-withdrawal; and no added E2 + P (Baseline). RNA-sequencing identified unique differentially expressed genes (DEGs) in all hormone conditions, but the majority tended to be downregulated in PPD and observed in E2 + P-addback. Two of these DEGs were evolutionarily conserved cellular stress regulators: IMPACT, an integrative response protein maintaining translational homeostasis, and WWTR1, a transcriptional coactivator in the 'Hippo' pathway mediating cell proliferation and survival. Correspondingly, significant gene network modules were linked to cell cycle progression, estrogen response, and immune dysregulation, suggesting innate differences in intracellular signaling in PPD. In certain hormone conditions, PPD LCLs displayed increased GATA3 expression (an upstream regulator of IMPACT and WWTR1) and differentially phosphorylated eiF2α (the ultimate downstream target of IMPACT). Taken together, these transcriptomic data primarily implicate innately dysregulated cellular responses as potentially influencing mood and/or escalating PPD risk. Furthermore, the intrinsic downregulation of IMPACT's translation and WWTR1's transcription networks may suggest a novel link between PPD and a compromised ability to maintain homeostasis in the context of cellular stress occurring during pregnancy and parturition.

Resveratrol alleviates postpartum depression-like behavior by activating autophagy via SIRT1 and inhibiting AKT/mTOR pathway.

BACKGROUND: Postpartum depression (PPD) causes maternal mortality, and has a high disability rate. In recent years, studies have suggested the Sirt1 gene to be involved in the pathogenesis of depression. Resveratrol (RSV), an activator of Sirt1, has been investigated in depressive behavior. However, its effect on PPD remains to be thoroughly elucidated. METHODS: We employed a mice model with bilateral oophorectomy combined with hormone-simulated pregnancy to assess postpartum depression-like behavior. The behavioral tests were performed 2 days after the withdrawal of estradiol benzoate. RSV was administered subcutaneously to the PPD model mice. Several behavioral tests were executed, including the open field test, forced swimming test, and tail suspension test. Western blot analyses and immunofluorescence staining were used to evaluate protein expression levels of SIRT1, autophagy markers, and the AKT/mTOR. RESULTS: Postpartum depressive-like behavior was triggered following the withdrawal of estradiol benzoate after hormone-stimulated-pregnancy. RSV improved postpartum depressive-like behavior of mice via its upregulation of the SIRT1 and autophagy markers, such as Beclin1, ATG5 and LC3B. Also, the downregulation of the p62 protein expression was observed. More importantly, we also detected the inhibition of phosphorylated AKT and mTOR in the hippocampus of postpartum depressive-like mice. CONCLUSION: RSV could alleviate postpartum depression-like behavior in mice by stimulating the SIRT1, induce autophagy and inhibit the AKT/ mTOR signaling pathway.

Paeoniflorin exhibits antidepressant activity in rats with postpartum depression via the TSPO and BDNF­mTOR pathways.

Postpartum depression (PPD) is the most common type of puerperal mental syndrome and affects maternal physical and mental health and even the growth and development of infants. Paeoniflorin exerts a potential antidepressive effect; however, the functional roles and potential mechanisms of paeoniflorin in PPD are still largely unknown. PPD rat models were prepared by withdrawing hormone­simulated pregnancy (HSP), and subjects were treated with paeoniflorin and fluoxetine or plasmids. The sucrose preference test (SPT), forced swimming test (FST) and tail suspension test (TST) were used to monitor depression­like behavior in rats. A radioimmunoassay was utilized for estradiol (E2) and progesterone (P) measurements. ELISA was performed to detect serum corticosterone (Cor), hippocampal allopregnanolone (Allo), IL­1ß and TNF­α levels. Expression of the E2 receptors ERα and ERß was detected by qPCR. Western blotting was used to detect TSPO, BDNF and mTOR phosphorylation. Paeoniflorin drastically increased the sucrose preference of rats while decreasing the immobility time in the FST and TST in PPD models. Moreover, paeoniflorin intervention upregulated serum E2, hippocampal Allo, ERα, and ERß levels but degraded P, serum Cor, IL­1ß, TNF­α and ERα/ERß levels. Mechanistically, paeoniflorin promoted TSPO and BDNF­mTOR pathway activation in PPD rats. Furthermore, suppression of TSPO or the BDNF­mTOR pathway partially reversed the effects of paeoniflorin on depression­like behaviors, hormone levels, and inflammatory cytokine release. Paeoniflorin may improve symptoms of PPD by regulating the TSPO and BDNF­mTOR pathways, indicating that paeoniflorin may be an effective anti­PPD and antidepressant drug, providing evidence for the future treatment of PPD.

Transcriptome-wide association study for postpartum depression implicates altered B-cell activation and insulin resistance.

Postpartum depression (PPD) affects 1 in 7 women and has negative mental health consequences for both mother and child. However, the precise biological mechanisms behind the disorder are unknown. Therefore, we performed the largest transcriptome-wide association study (TWAS) for PPD (482 cases, 859 controls) to date using RNA-sequencing in whole blood and deconvoluted cell types. No transcriptional changes were observed in whole blood. B-cells showed a majority of transcriptome-wide significant results (891 transcripts representing 789 genes) with pathway analyses implicating altered B-cell activation and insulin resistance. Integration of other data types revealed cell type-specific DNA methylation loci and disease-associated eQTLs (deQTLs), but not hormones/neuropeptides (estradiol, progesterone, oxytocin, BDNF), serve as regulators for part of the transcriptional differences between cases and controls. Further, deQTLs were enriched for several brain region-specific eQTLs, but no overlap with MDD risk loci was observed. Altogether, our results constitute a convergence of evidence for pathways most affected in PPD with data across different biological mechanisms.

Prospective Investigation of Glutamate Levels and Percentage Gray Matter in the Medial Prefrontal Cortex in Females at Risk for Postpartum Depression.

BACKGROUND: The substantial female hormone fluctuations associated with pregnancy and postpartum have been linked to a greater risk of developing depressive symptoms, particularly in high-risk women (HRW), i.e. those with histories of mood sensitivity to female hormone fluctuations. We have shown that glutamate (Glu) levels in the medial prefrontal cortex (MPFC) decrease during perimenopause, a period of increased risk of developing a major depressive episode. Our team has also demonstrated that percentage gray matter (%GM), another neural correlate of maternal brain health, decreases in the MPFC during pregnancy. OBJECTIVE: To investigate MPFC Glu levels and %GM from late pregnancy up to 7 weeks postpartum in HRW and healthy pregnant women (HPW). METHODS: Single-voxel spectra were acquired from the MPFC of 41 HPW and 22 HRW using 3- Tesla in vivo proton magnetic resonance spectroscopy at five different time points. RESULTS: We observed a statistically significant interaction between time and group for the metabolite Glu, with Glu levels being lower for HRW during pregnancy and early postpartum (p<0.05). MPFC %GM was initially lower during pregnancy and then significantly increased over time in both groups (p<0.01). CONCLUSION: This investigation suggests that the vulnerability towards PPD is associated with unique fluctuations of MPFC Glu levels during pregnancy and early postpartum period. Our results also suggest that the decline in MPFC %GM associated with pregnancy seems to progressively recover over time. Further investigations are needed to determine the specific role that female hormones play on the physiological changes in %GM during pregnancy and postpartum.

Ameliorative effect of SIRT1 in postpartum depression mediated by upregulation of the glucocorticoid receptor.

Recent evidence has confirmed the association of glucocorticoid receptor (GR) gene variants with the "stress" endocrine axis in postpartum depression (PPD). Sirtuin 1(SIRT1) is an NAD+-dependent histone deacetylase and transcriptional enhancer of GR. However, to date, the function of the SIRT1 gene in the regulation of GR expression in PPD remains to be fully determined. A hormone-stimulated pregnancy (HSP) and subsequent "postpartum" withdrawal of estrogen was employed to mimic the fluctuations in estradiol associated with pregnancy and postpartum. We confirmed that estradiol benzoate withdrawal (EW)-rats displayed depression- and anxiety-like behaviors. These behavioral dysfunctions are associated with attenuated expression of SIRT1 and GR in the hippocampus. To assess the role of SIRT1, as well as its regulatory target directly, a selective SIRT1 activator (SRT2104) was infused into the hippocampus of EW-rats. We found that pharmacological activation of hippocampal SIRT1 blocks the development of depression-related, but not anxiety-related, phenotypes of PPD. In addition, the activation of SIRT1 leads to an increase in hippocampal GR expression in EW-rats. We further confirmed that SIRT1 physically interacts with GR in a glucocorticoid-dependent manner. Taken together, our results suggest that neuropathology in PPD is caused, at least in part, by the inhibition of the SIRT1-GR signaling pathway. Elevating SIRT1 levels, either pharmacologically or through other means, could represent a therapeutic strategy for PPD.

The combination of fluoxetine and environmental enrichment reduces postpartum stress-related behaviors through the oxytocinergic system and HPA axis in mice.

Gestational stress can increase postpartum depression in women. To treat maternal depression, fluoxetine (FLX) is most commonly prescribed. While FLX may be effective for the mother, at high doses it may have adverse effects on the fetus. As environmental enrichment (EE) can reduce maternal stress effects, we hypothesized that a subthreshold dose of FLX increases the impact of EE to reduce anxiety and depression-like behavior in postpartum dams exposed to gestational stress. We evaluated this hypothesis in mice and to assess underlying mechanisms we additionally measured hypothalamic-pituitary-adrenal (HPA) axis function and brain levels of the hormone oxytocin, which are thought to be implicated in postpartum depression. Gestational stress increased anxiety- and depression-like behavior in postpartum dams. This was accompanied by an increase in HPA axis function and a decrease in whole-brain oxytocin levels in dams. A combination of FLX and EE remediated the behavioral, HPA axis and oxytocin changes induced by gestational stress. Central administration of an oxytocin receptor antagonist prevented the remediating effect of FLX + EE, indicating that brain oxytocin contributes to the effect of FLX + EE. These findings suggest that oxytocin is causally involved in FLX + EE mediated remediation of postpartum stress-related behaviors, and HPA axis function in postpartum dams.

A Primer on DNA Methylation and Its Potential to Impact Maternal Depression Risk and Assessment During Pregnancy and the Postpartum.

Depression onset during and after pregnancy is prevalent and associated with significant implications for maternal, child, and family health. Although environmental risk factors important to the expression of pregnancy-related depression are well known, knowledge of the genetic underpinning is limited. Given the joint contribution of environmental and genetic factors to depression risk liability, DNA methylation presents itself as an ideal biomarker to investigate basic mechanisms and opportunities for translational research to care for pregnancy-related depression health outcomes. This article is an introduction to DNA methylation and its potential to serve as a marker of depression risk during pregnancy and the postpartum. This commentary discusses current clinical uses of DNA methylation-based testing and how it may be applied to perinatal depression clinical care and management.

Transdermal delivery of breakthrough therapeutics for the management of treatment-resistant and post-partum depression.

For the first time in over three decades, the year 2019 saw the approval of two new classes of antidepressants: Spravato™ esketamine intranasal spray for treatment-resistant depression, and Zulresso® brexanolone infusion against post-partum depression. Although both therapies were granted "breakthrough" designations, topical application of both drugs could offer several advantages over their current routes of administration. However, delivery of their high therapeutic doses (0.5 mg/kg ketamine in 1 h; 90 µg/kg/h brexanolone over 52 h) is unachievable by conventional means. We evaluated physical enhancement techniques such as iontophoresis, microneedle-treatment, and ablative laser for the rapid delivery of ketamine. Additionally, the sustained delivery of brexanolone across microporated skin employing chemical enhancers and novel microemulsions was also accomplished. The target therapeutic flux of ketamine after skin pre-treatment with laser (534.51 ± 146.93 µg/cm2), and the application of anodal iontophoresis (681.93 ± 74.35 µg/cm2) on ablated skin, was observed within one hour. Microporation of skin using laser was more effective than microneedles, for the delivery of ketamine as well as brexanolone. The developed microemulsions resulted in significantly higher transdermal delivery across laser-treated skin. Although brexanolone demonstrated higher solubility in the w/o microemulsion (21.31 ± 0.14 mg/mL) than the o/w microemulsion (10.69 ± 0.09 mg/mL), percutaneous absorption from the o/w microemulsion (6.04 ± 0.16%) was significantly higher than the w/o microemulsion (1.92 ± 0.02%).

Maternal Separation Model of Postpartum Depression: Potential Role for Nucleus Accumbens Dopamine D1-D2 Receptor Heteromer.

Postpartum depression is a mood disorder with a distinct neurobiological and behavioural profile occurring during and after the postpartum period. Dopamine pathways in the limbic regions of the brain such as the nucleus accumbens (NAc) have been shown to be involved in the etiology of depressive disorders. Selective activation of the dopamine D1-D2 receptor heteromer has been demonsrated to cause depressive- and anxiogenic-like behaviours in rats. The maternal separation model involving three hour daily maternal separation (MS) from pups on PPD 2-15 on anxiety-, depression- and anhedonia-like behaviors in the dams was investigated, together with plasma corticosterone, oxytocin and D1-D2 heteromer expression in the NAc core and shell in non-MS and MS dams. Depression, anxiety and anhedonia-like behaviours were measured using the forced swim test, elevated plus maze and sucrose preference test, respectively. In comparison to non-MS controls, MS dams displayed slightly higher depressive and anxiety-like behaviours with no difference in anhedonia-like behaviours. The MS dams displayed significantly increased care of pups after their retrieval with higher bouts of nursing, lower latency to nurse, lower bouts of out nest behaviour and decreased self-care. There was no significant alteration in D1-D2 heteromer expression in NAc core and shell between mothers of either group (MS, non-MS) or between postpartum rats and nonpregnant female rats, remaining higher than in male rats. This data provides evidence for the maternal separation model in producing a postpartum depression-like profile, but with maternal resilience able to modify behaviours to counteract any potential deleterious consequences to the pups.

Mating and parenting experiences sculpture mood-modulating effects of oxytocin-MCH signaling.

The two hypothalamic neuropeptides oxytocin and melanin concentrating hormone (MCH) share several physiological actions such as the control of maternal care, sexual behavior, and emotions. In this study, we uncover the role for the oxytocin-MCH signaling pathway in mood regulation. We identify discrete effects of oxytocin-MCH signaling on depressive behavior and demonstrate that parenting and mating experiences shape these effects. We show that the selective deletion of OXT receptors from MCH neurons increases and decreases depressive behavior in sexually naïve and late postpartum female mice respectively, with no effect on sexually naïve male mice. We demonstrate that both parenting experience and mood-regulating effects of oxytocin-MCH are associated with synaptic plasticity in the reward and fear circuits revealed by the alterations of Arc expressions, which are associated with the depressive behavior. Finally, we uncover the sex-dependent effects of mating on depressive behavior; while the sexual activity reduces the basal levels of depressive behavior in male mice, it reduces in female mice evoked-depression only. We demonstrate that the oxytocin-MCH pathway mediates the effects of sexual activity on depressive behavior. Our data suggest that the oxytocin-MCH pathway can serve as a potential therapeutic target for the treatment of major depression and postpartum mood disorders.

N-3 PUFA improved pup separation-induced postpartum depression via serotonergic pathway regulated by miRNA.

Stress and ovarian hormone fluctuation are risk factors for postpartum depression (PPD). Previous studies suggested antidepressant-like effects of n-3 polyunsaturated fatty acids (PUFA), but their effect on dam animal with additional stress were not clear. The purpose of the present study was to investigate the hypothesis that n-3 PUFA improved PPD through the serotonergic and glutamatergic pathways by modulating miRNA. Rats were fed n-3 PUFA or control diet from gestation, with pup separation (PS) on postpartum days 2-14 and non-PS controls. N-3 PUFA reversed PS-induced depressive behaviors, including increased immobility, latencies to contact first pup and retrieve all pups, and decreased sucrose preference. N-3 PUFA also modulated the hypothalamic-pituitary-adrenal (HPA) axis by decreasing circulating levels of adrenocorticotropic hormone and corticosterone and expression of hypothalamic corticotrophin releasing factor and hippocampal miRNA-218 but increasing the hippocampal expression of glucocorticoid receptor. N-3 PUFA inhibited neuroinflammation by decreasing circulating levels of prostaglandin E2 and hippocampal expression of tumor necrosis factor-α, interleukin-6, and miRNA-155. In addition, n-3 PUFA up-regulated the serotonergic pathway by increasing circulating levels of serotonin and hippocampal expression of serotonin-1A receptor, cAMP response element binding protein (CREB), pCREB, brain-derived neurotrophic factor, and miRNA-182 but did not affect the glutamatergic pathway according to the hippocampal expression of N-methyl-D-aspartate receptor-2B. The present study suggested that n-3 PUFA improved PPD through the serotonergic pathway by modifying the HPA axis, neuroinflammation, and related miRNAs.

LncRNA Gm14205 induces astrocytic NLRP3 inflammasome activation via inhibiting oxytocin receptor in postpartum depression.

Postpartum depression (PPD) is a kind of mental disorder characterized by persistent low emotions in puerperium. The most significant physiological change in postpartum is lactation which is regulated by oxytocin receptor (OXTR). However, whether OXTR is related to pathological process of PPD and the potential mechanism still remain unclear. In the present study, we prepared hormone-simulated pregnancy (HSP)-induced PPD mouse model and found that the protein level of OXTR in hippocampus of PPD model mice was down-regulated and Nod-like receptor protein 3 (NLRP3) inflammasome was activated. We identified five long non-coding RNAs (lncRNAs) related to PPD by transcriptome sequencing, including three up-regulated and two down-regulated. The five lncRNAs were associated with the signaling pathway of OXTR according to the bioinformatics analysis. Furthermore, we focused on one of the five lncRNAs, Gm14205, and found that it targeted OXTR which inhibited astrocytic NLRP3 inflammasome activation in hippocampal primary astrocytes. These findings illustrate that OXTR has protective effects in PPD by inhibiting NLRP3 inflammasome activation and provides a new strategy for targeting lncRNA Gm14205 in the pathogenesis of PPD.

Advances in treatment for postpartum major depressive disorder.

Introduction: Postpartum depressive disorder (PPD) is a burdensome medical condition. To date, only one treatment (Brexanolone) has undergone registrational trials and is approved in the United States with an indication for the treatment of PPD. However, other treatments are prescribed and have been tested for this condition. Herein, the authors review the available scientific evidence pertaining to the somatic treatments of PPD. Areas covered: The authors evaluate the published open-label and randomized controlled trials (RCTs), examine the biological mechanisms of PPD treatments, and evaluate how the available data translates into information that may be useful for clinical practice. Expert opinion: Antidepressants have long been the mainstay of PPD treatment, despite the limited evidence from randomized clinical trials that supports this practice. Brexanolone improves treatment options for women with PPD. However, the relatively burdensome administration and monitoring protocol, along with the high cost of the medication, limit the possibility for an extensive use of this medication. Large, randomized, controlled trials of hormonal treatments in patients with PPD are warranted. Also, treatment with mood stabilizers and/or antipsychotics in women with major depressive disorder, who meet the DSM-5 mixed features specifiers in the post-partum period, should be tested in controlled clinical trials.

Postpartum fluoxetine increased maternal inflammatory signalling and decreased tryptophan metabolism: Clues for efficacy.

Perinatal depression (PND) affects approximately 15% of women, and de novo postpartum depression affects approximately 40% of PND cases. Selective serotonin reuptake inhibitors (SSRIs) are a common class of antidepressants prescribed to treat PND. However, the safety and efficacy of SSRIs have been questioned in both clinical and preclinical research. Here, using a preclinical rodent model of de novo postpartum depression, we aim to better understand neuroinflammatory cytokines and tryptophan mechanisms that may be related to SSRI efficacy. Rat dams were treated with high corticosterone (CORT; 40 mg/kg, s.c.) for 22 days in the postpartum period to simulate a depressive-like endophenotype. Concurrently, a subset of dams was treated with the SSRI, fluoxetine (FLX; 10 mg/kg, s.c.), in the postpartum period. We showed, consistent with previous studies, that although maternal FLX treatment prevented CORT-induced disturbances in maternal care behavior during the early postpartum, it failed to prevent the expression of CORT-induced passive coping behavior in the late postpartum. Furthermore, FLX treatment, regardless of CORT treatment, increased maternal hippocampal IL-1ß, plasma CXCL1, and decreased maternal plasma tryptophan, 4'-pyridoxic acid, and pyridoxal concentrations. Maternal CORT treatment reduced maternal hippocampal IFN-γ, and both hippocampal and plasma TNF-α. Our work suggests that the limited efficacy of FLX in the late postpartum may be associated with elevated levels of the proinflammatory cytokine IL-1ß in the maternal hippocampus, elevated plasma CXCL1, decreased plasma tryptophan concentration, and changes in vitamin B6 dependent tryptophan-kynurenine pathway. These findings suggest novel pathways for improving SSRI efficacy in alleviating perinatal depression.

Anxiolytic and Anti-depressive Like Effects of Translocator Protein (18 kDa) Ligand YL-IPA08 in a Rat Model of Postpartum Depression.

Translocator protein 18 kDa (TSPO) is mainly distributed in the outer mitochondrial membrane of steroid-synthesizing cells in the central and peripheral nervous systems. It mediates cholesterol transportation across the phospholipid membrane, which is a prerequisite for neurosteroid synthesis. Though the ligand of TSPO has clinical value in the diagnosis and treatment of neuropsychiatric disorders, the pharmacological study of TSPO for anti-postpartum depression has not been reported. In this study, the classical method of reproductive hormone withdrawal was used to construct a rat model of postpartum depression (PPD). The effect of YL-IPA08, a new ligand compound of TSPO, on PPD was evaluated using multiple behavioral tests at progressive time points. Additionally, real-time quantitative PCR, Western-blotting and an enzyme linked immunosorbent assay were conducted to elucidate the potential molecular mechanism of such effect. We report that the levels of TSPO and neurosteroids in the hippocampus and prefrontal cortex were significantly decreased in PPD rats compared to healthy controls. After 3 weeks of drug treatment, the levels of TSPO and neurosteroids in the hippocampus of PPD rats were increased, and anxiety and depressive like behaviors were alleviated. Meanwhile, compared with sertraline treatment, a positive control in this study, YL-IPA08 treatment had a shorter onset time. Our results suggest that the anxiolytic and anti-depressive activity of YL-IPA08 has significant value in the treatment of PPD and that TSPO may be a potential new target for the treatment of PPD.