Deficiency in Androgen Receptor Aggravates the Depressive-Like Behaviors in Chronic Mild Stress Model of Depression

Brain region-specific roles of brain-derived neurotrophic factor in social stress-induced depressive-like behavior

Brain-derived neurotrophic factor is a key factor in stress adaptation and avoidance of a social stress behavioral response. Recent studies have shown that brain-derived neurotrophic factor expression in stressed mice is brain region-specific, particularly involving the corticolimbic system, including the ventral tegmental area, nucleus accumbens, prefrontal cortex, amygdala, and hippocampus. Determining how brain-derived neurotrophic factor participates in stress processing in different brain regions will deepen our understanding of social stress psychopathology. In this review, we discuss the expression and regulation of brain-derived neurotrophic factor in stress-sensitive brain regions closely related to the pathophysiology of depression. We focused on associated molecular pathways and neural circuits, with special attention to the brain-derived neurotrophic factor-tropomyosin receptor kinase B signaling pathway and the ventral tegmental area-nucleus accumbens dopamine circuit. We determined that stress-induced alterations in brain-derived neurotrophic factor levels are likely related to the nature, severity, and duration of stress, especially in the above-mentioned brain regions of the corticolimbic system. Therefore, BDNF might be a biological indicator regulating stress-related processes in various brain regions.

The microRNA-29ab1/Zfp36/AR Axis in the Hypothalamus Regulates Male-Typical Behaviors in Mice

Male-typical behaviors such as aggression and mating, which reflect sexual libido in male mice, are regulated by the hypothalamus, a crucial part of the nervous system. Previous studies have demonstrated that microRNAs (miRNAs), especially miR-29, play a vital role in reproduction and the neural control of behaviors. However, it remains unclear whether miR-29 affects reproduction through the hypothalamus-mediated regulation of male-typical behaviors. Here, we constructed two mouse knockout models by ablating either the miR-29ab1 or miR-29b2c cluster. Compared to WT, the ablation of miR-29ab1 in male mice significantly reduced the incidence of aggression by 60% and the incidence of mating by 46.15%. Furthermore, the loss of miR-29ab1 in male mice led to the downregulation of androgen receptor (AR) in the ventromedial hypothalamus. Transcriptomic analysis of the hypothalamus of miR-29ab1-deficient mice revealed inflammatory activation and aberrant expression of genes associated with male-typical behaviors, including Ar, Pgr, Htr4, and Htr2c. Using bioinformatics analysis and dual-luciferase reporter assays, we identified zinc finger protein 36 (Zfp36) as a direct downstream target gene of miR-29ab1. We subsequently showed that ZFP36 colocalized with AR in GT1-7 cells. Furthermore, inhibition of Zfp36 or RelB in GT1-7 cells led to an increase in AR expression. Collectively, our results demonstrate that the miR-29ab1/Zfp36/AR axis in the hypothalamus plays a pivotal role in the regulation of aggression and mating in male mice, providing a potential therapeutic target for treating infertility caused by low libido.

Antistress Effects of Terpinen-4-ol and Compounds of Mimicked Yuzu Synthetic Fragrance in Humans and Mice

This study investigated the antistress effects of yuzu synthetic fragrances by employing three experiments on humans and mice using two yuzu synthetic fragrances and five single compounds. We prepared two synthetic fragrances based on the component analysis of two natural yuzu essential oils extracted by cold-pressed and steam-distilled extraction methods. Chromogranin A (CgA) and heart rate (HR) were used as stress indices in human experiments. Immobility time during the forced swim test was used as a stress index in mice experiments. We analyzed brain mechanisms by measuring the expression of neurotrophic factors, brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), and neurotrophin-3 (NT-3) in the mice experiments. Synthetic yuzu fragrance mimicked steam-distilled oil (SD) significantly reduced participants' heart rate in experiment 1. In the forced swim test conducted in experiment 2, SD significantly reduced immobility time, and increased the expression of neurotrophic factors BDNF, NGF, and NT-3 in the hippocampus of mice. In experiment 3, focusing on single compounds, terpinen-4-ol significantly reduced immobility time in the forced swim test. These findings indicate that inhalation of SD and terpinen-4-ol has antistress effects. Terpinen-4-ol is a strong candidate for further investigation as a potential stress-reducing agent.

Effects of testosterone dose on depression-like behavior among castrated adult male rats

Previous research has shown a decrease in serum testosterone levels in male patients with depression. In recent years, the results of testosterone replacement therapy (TRT) to improve depression have been mixed. Using the classic CUMS model, we induced depressive-like behaviors in rats and observed a decrease in their serum testosterone levels along with an increase in androgen receptor expression in the hippocampus. We then performed castration and sham surgery on male rats and found that testosterone deprivation led to the manifestation of depressive-like behavior that could be ameliorated by TRT. Through a repeated measures experiment consisting of five blocks over a period of 25 days, we discovered that the reduction in depressive-like behavior in testosterone-deprived rats began 22 days after drug administration (0.5 and 0.25 mg/rat). Furthermore, rats in 0.5mgT group showed the most significant improvements. Subsequently, this dose was used in CUMS rats and reduced the occurrence of depressive-like behaviors. Our study has demonstrated the complex interplay between depression and testosterone, as well as the intricate dose-response relationship between TRT and reduction in depression. Our research supports the use of TRT to alleviate depression, but dosage and duration of treatment are critical factors in determining efficacy.

Androgen regulation of behavioral stress responses and the hypothalamic-pituitary-adrenal axis

Testosterone is a powerful steroid hormone that can impact the brain and behavior in various ways, including regulating behavioral and neuroendocrine (hypothalamic-pituitary-adrenal (HPA) axis) stress responses. Early in life androgens can act to alter development of brain regions associated with stress regulation, which ultimately impacts the display of stress responses later in life. Adult circulating androgens can also influence the expression of distinct genes and proteins that regulate stress responses. These changes in the brain are hypothesized to underlie the potent effects of androgens in regulating behaviors related to stress and stress-induced activation of the HPA axis. Androgens can induce alterations in these functions through direct binding to the androgen receptor (AR) or following conversion to estrogens and subsequent binding to estrogen receptors including estrogen receptor alpha (ERα), beta (ERβ), and G protein-coupled estrogen receptor 1 (GPER1). In this review, we focus on the role of androgens in regulating behavioral and neuroendocrine stress responses at different stages of the lifespan and the sex hormone receptors involved in regulating these effects. We also review the specific brain regions and cell phenotypes upon which androgens are proposed to act to regulate stress responses with an emphasis on hypothalamic and extended amygdala subregions. This knowledge of androgen effects on these neural systems is critical for understanding how sex hormones regulate stress responses.

BDNF Modulation by microRNAs: An Update on the Experimental Evidence

MicroRNAs can interfere with protein function by suppressing their messenger RNA translation or the synthesis of its related factors. The function of brain-derived neurotrophic factor (BDNF) is essential to the proper formation and function of the nervous system and is seen to be regulated by many microRNAs. However, understanding how microRNAs influence BDNF actions within cells requires a wider comprehension of their integrative regulatory mechanisms. Aim: In this literature review, we have synthesized the evidence of microRNA regulation on BDNF in cells and tissues, and provided an analytical discussion about direct and indirect mechanisms that appeared to be involved in BDNF regulation by microRNAs. Methods: Searches were conducted on PubMed.gov using the terms "BDNF" AND "MicroRNA" and "brain-derived neurotrophic factor" AND "MicroRNA", updated on 1 September 2023. Papers without open access were requested from the authors. One hundred and seventy-one papers were included for review and discussion. Results and Discussion: The local regulation of BDNF by microRNAs involves a complex interaction between a series of microRNAs with target proteins that can either inhibit or enhance BDNF expression, at the core of cell metabolism. Therefore, understanding this homeostatic balance provides resources for the future development of vector-delivery-based therapies for the neuroprotective effects of BDNF.

Intranasal delivery of paroxetine: A preclinical study on pharmacokinetics, depressive-like behaviour, and neurochemical sex differences

Treatment of major depressive disorder remains a major unmet clinical need. Given the advantages of intranasal administration for targeted brain delivery, the present study aimed at investigating the pharmacokinetics of paroxetine, after its intranasal instillation and assessing its potential therapeutic effect on female and male mice subjected to unpredictable chronic mild stress (UCMS) protocol. IN administration revealed direct nose-to-brain paroxetine delivery but dose- and sex-dependent differences. Pharmacokinetics was nonlinear and paroxetine concentrations were consistently higher in plasma and brain of male mice. Additionally, UCMS decreased animal preference for sucrose in both male and female mice following acute (p < 0.01) and chronic stress (p < 0.05), suggesting anhedonia. Both male and female mice exhibited depressive-like behavior in the forced swimming test. UCMS females displayed a significantly longer immobility time and shorter climbing time than the control group (p < 0.05), while no differences were found between male mice. Two weeks of paroxetine intranasal administration reduced immobility time and lengthened climbing and swimming time, approaching values similar to those observed in the healthy control group. The therapeutic effect was stronger on female mice. Importantly, melatonin plasma levels were significantly decreased in female mice following UCMS (p < 0.05), while males exhibited heightened corticosterone levels. On the other hand, treatment with IN paroxetine significantly increased corticosterone and melatonin levels in both sexes compared to healthy mice (p < 0.05). Intranasal paroxetine delivery undoubtedly ameliorated the behavioral despair, characteristic of depressive-like animals. Despite its efficiency in male and female mice subjected to UCMS, females were more prone to this novel therapeutic strategy.

miR-204-5p Plays a Critical Role in the Pathogenesis of Depression and Anti-depression Action of Venlafaxine in the Hippocampus of Mice

BACKGROUND

Venlafaxine has been demonstrated to treat diseases such as social anxiety disorder and depression. Most of antidepressants including venlafaxine have a certain effect, but significant side effects. Therefore, it is necessary for us to research the development of novel antidepressants for effective treatment in practice. MicroRNA-204 (miR-204) is highly expressed in brain tissue, and plays a critical role in the synaptic plasticity of hippocampal neurons in rats. However, the underlying molecular mechanism of miR-204 remains unclear to date, this study aims to offer unique insights into depression and provide a theoretical basis for clinical physicians.

METHODS

A chronic social defeat stress (CSDS) was initially adopted for establishing a mice model of depression in this research and depression-like behaviors were evaluated by a series of behavioral experiments including the sucrose preference test (SPT), the tail suspension test (TST), the forced swim test (FST) and the social interaction test (SIT). Quantitative real-time reverse transcription PCR (qRT-PCR) was also conducted to test the expression levels of miR-204 and BDNF in the hippocampus of mice. Finally, gene interference of miR-204-5p was further adopted to test whether miR-204-5p played an effective role in the antidepressant effects of venlafaxine in mice.

RESULTS

Our data implicated that CSDS significantly increased the miR-204-5p but not miR-204-3p levels in the hippocampus of mice. The treatment of venlafaxine obviously relieved depression- like behaviors of CSDS-induced mice. The usage of venlafaxine abolished the increasing effects on the expression of miR-204-5p but up-regulated the BDNF expression level in CSDS-exposured mice. More importantly, we found that genetic overexpression of miR-204-5p decreased the reverse effects of venlafaxine on depressive-like behaviors and genetic knockdown of hippocampal miR-204-5p relieved the depressive-like behaviors and neurogenesis in CSDS-induced mice.

CONCLUSION

miR-204-5p played an effective role in the antidepressant effects of venlafaxine in CSDS-induced mice.

Enduring sex-dependent effects of lipopolysaccharide treatment on the hypothalamic-pituitary-gonadal axis in mice

Pubertal stress causes enduring sexual behavior dysfunction in males and females, but the underlying mechanism remains unknown. These changes may arise from pubertal programming of the hypothalamic-pituitary-gonadal axis. Previous findings show that stress exposure downregulates the hypothalamic-pituitary-gonadal axis, particularly through the reduction of the neuropeptide kisspeptin (Kiss1) and its receptor (Kiss1R). Although acute changes in kiss1 and Kiss1r genes have been observed following pubertal immune stress, it is unclear whether immune stress-induced downregulation of kiss1 and kiss1r persists beyond puberty. The current study investigated the enduring sex-specific consequences of lipopolysaccharide on the expression of Kiss1 and Kiss1r in 160 pubertal or adult mice at multiple time points. Six-week and 10-week-old male and female mice were treated with either saline or with lipopolysaccharide. Mice were euthanized either 8 h or 4 weeks following treatment. Although we did not identify any sex differences, our results revealed that lipopolysaccharide treatment decreases hypothalamic Kiss1 and Kiss1r in both pubertal and adult mice within 8 h of treatment. The decreased hypothalamic Kiss1 expression persists 4 weeks later only in mice treated with lipopolysaccharide during puberty. Our findings highlight the age-dependent vulnerability of the hypothalamic-pituitary-gonadal axis to immune stress, providing a better understanding of the mechanisms implicated in allostatic shift during immune stress. Finally, our findings also show the effects of immune stress on various components of the hypothalamic-pituitary-gonadal axis, which could have implications for sexual and fertility-related dysfunctions.

Hair androgen concentrations and depressive disorders in adolescents from the general population

Although the link between androgens and depression is well established in adults, the effects of cofactors on this association are less clearly understood, particularly in youth. Epidemiological cohort study of adolescents in Dresden, Germany. Analyses comprised data of 985 individuals assessed at baseline and of 512 individuals at 1-year follow-up. We investigated multivariable regression models for cross-sectional and longitudinal associations of hair testosterone, dehydroepiandrosterone (DHEA), and their cortisol ratios with 12-month diagnoses of major depressive disorder (MDD) and MDD without any anxiety disorder assessed with standardized diagnostic interview (DIA-X-5), and with dimensional depression scores (PHQ-9, PROMIS), separately for males and females. The potential moderating effect of social support was determined. Cross-sectional analyses yielded inverse associations of testosterone and DHEA with MDD and MDD without any anxiety disorders in males. In cross-sectional and longitudinal analyses, baseline ratio cortisol/DHEA was significantly, inversely associated to PROMIS-depression in males. Only cross-sectional associations for ratio cortisol/DHEA and PROMIS-depression remained significant after Bonferroni-Holm correction. No robust associations were observed in female participants. Social support exerted no consistent moderating effect on the investigated association. The present observational cohort study showed no consistent association of hair androgen concentrations with depressive disorders in adolescents. However, findings provide some support for the association between the cortisol/DHEA ratio and depression in males. Longitudinal research designs in large samples are needed to understand the interplay between androgens, depression, and developmental and social factors in youth.

The Mechanisms Underlying the Pharmacological Effects of GuiPi Decoction on Major Depressive Disorder based on Network Pharmacology and Molecular Docking

BACKGROUND AND AIM

Major Depressive Disorder (MDD) is a common affective disorder. GuiPi decoction (GPD) is used to treat depression in China, Japan, and Korea. However, its effective ingredients and antidepressant mechanisms remain unclear. We attempted to reveal the potential mechanisms of GPD in the treatment of MDD by network pharmacology and molecular docking. In addition, we conducted an enzymatic activity assay to validate the results of molecular docking.

METHODS

GPD-related compounds and targets, and MDD-related targets were retrieved from databases and literature. The herb-compound-target network was constructed by Cytoscape. The protein- protein interaction network was built using the STRING database to find key targets of GPD on MDD. Enrichment analysis of shared targets was analyzed by MetaCore database to obtain the potential pathway and biological process of GPD on MDD. The main active compounds treating MDD were screened by molecular docking. The PDE4s inhibitors were screened and verified by an enzyme activity assay.

RESULTS

GPD contained 1222 ingredients and 190 potential targets for anti-MDD. Possible biological processes regulated by GPD were neurophysiological processes, blood vessel morphogenesis, Camp Responsive Element Modulator (CREM) pathway, and Androgen Receptor (AR) signaling crosstalk in MDD. Potential pathways in MDD associated with GPD include neurotransmission, cell differentiation, androgen signaling, and estrogen signaling. Fumarine, m-cresol, quercetin, betasitosterol, fumarine, taraxasterol, and lupeol in GPD may be the targets of SLC6A4, monoamine oxidase A (MAOA), DRD2, OPRM1, HTR3A, Albumin (ALB), and NTRK1, respectively. The IC50 values of trifolin targeting Phosphodiesterase (PDE) 4A and girinimbine targeting PDE4B1 were 73.79 μM and 31.86 μM, respectively. The IC50 values of girinimbine and benzo[a]carbazole on PDE4B2 were 51.62 μM and 94.61 μM, respectively.

CONCLUSION

Different compounds in GPD may target the same protein, and the same component in GPD can target multiple targets. These results suggest that the effects of GPD on MDD are holistic and systematic, unlike the pattern of one drug-one target.

Sex steroid hormones in depressive disorders as a basis for new potential treatment strategies

The sex steroid hormones (SSHs) such as testosterone, estradiol, progesterone, and their metabolites have important organizational and activational impacts on the brain during critical periods of brain development and in adulthood. A variety of slow and rapid mechanisms mediate both organizational and activational processes via intracellular or membrane receptors for SSHs. Physiological concentrations and distribution of SSHs in the brain result in normal brain development. Nevertheless, dysregulation of hormonal equilibrium may result in several mood disorders, including depressive disorders, later in adolescence or adulthood. Gender differences in cognitive abilities, emotions as well as the 2-3 times higher prevalence of depressive disorders in females, were already described. This implies that SSHs may play a role in the development of depressive disorders. In this review, we discuss preclinical and clinical studies linked to SSHs and development of depressive disorders. Our secondary aim includes a review of up-to-date knowledge about molecular mechanisms in the pathogenesis of depressive disorders. Understanding these molecular mechanisms might lead to significant treatment adjustments for patients with depressive disorders and to an amelioration of clinical outcomes for these patients. Nevertheless, the impact of SSHs on the brain in the context of the development of depressive disorders, progression, and treatment responsiveness is complex in nature, and depends upon several factors in concert such as gender, age, comorbidities, and general health conditions.

[Effect of inhibiting miR-204 expression on the learning and memory abilities of neonatal rats with intrauterine growth restriction and related mechanism]

OBJECTIVES

To investigate the effect of inhibiting miR-204 expression on the learning and memory abilities of neonatal rats with intrauterine growth restriction (IUGR) and related mechanism.

METHODS

A rat model of IUGR was prepared by low-protein diet. The 3-day-old IUGR rats were divided into three groups: model, miRNA antagonist control and miR-204 antagonist, with 10 rats in each group. Ten normal neonatal rats served as the control group. Morris water maze test was used to measure the learning and memory abilities of the rats. Quantitative real-time PCR was used to measure the mRNA expression levels of miR-204 and brain-derived neurotrophic factor (BDNF) in the hippocampus. Nissl staining and TUNEL staining were used to observe the number of Nissl bodies and the apoptosis of cells in the hippocampus. Western blot was used to measure the expression levels of BDNF/TrkB signaling pathway-related proteins in the hippocampus.

RESULTS

Compared with the control group, the model group had a significant increase in the escape latency and a significant reduction in the number of platform crossings (P<0.001). The model group also had significant increases in the apoptosis rate of cells and the expression level of miR-204 in hippocampal tissue (P<0.001), while the number of Nissl bodies, the mRNA expression level of BDNF, and the protein expression levels of BDNF, p-TrkB, and p-CREB in the model group were significantly reduced compared with the control group (P<0.001). After inhibition of the expression of miR-204, the number of Nissl bodies, the mRNA expression level of BDNF, and the protein expression levels of BDNF, p-TrkB, and p-CREB significantly increased, while the cell apoptosis rate and the expression level of miR-204 in the hippocampus significantly decreased. The escape latency was also reduced, while the number of platform crossings increased after inhibition of the expression of miR-204 (P<0.001).

CONCLUSIONS

Inhibiting miR-204 can improve the learning and memory functions of neonatal rats with IUGR, possibly by targeted activation of the BDNF/TrkB signaling pathway.

The role of testosterone, the androgen receptor, and hypothalamic-pituitary-gonadal axis in depression in ageing Men

Considerable research has shown that testosterone regulates many physiological systems, modulates clinical disorders, and contributes to health outcome. However, studies on the interaction of testosterone levels with depression and the antidepressant effect of testosterone replacement therapy in hypogonadal men with depression have been inconclusive. Current findings indicate that low circulating levels of total testosterone meeting stringent clinical criteria for hypogonadism and testosterone deficiency induced by androgen deprivation therapy are associated with increased risk for depression and current depressive symptoms. The benefits of testosterone replacement therapy in men with major depressive disorder and low testosterone levels in the clinically defined hypogonadal range remain uncertain and require further investigation. Important considerations going forward are that major depressive disorder is a heterogeneous phenotype with depressed individuals differing in inherited polygenic determinants, onset and clinical course, symptom complexes, and comorbidities that contribute to potential multifactorial differences in pathophysiology. Furthermore, polygenic mechanisms are likely to be critical to the biological heterogeneity that influences testosterone-depression interactions. A genetically informed precision medicine approach using genes regulating testosterone levels and androgen receptor sensitivity will likely be essential in gaining critical insight into the role of testosterone in depression.

Centering the Needs of Transgender, Nonbinary, and Gender-Diverse Populations in Neuroendocrine Models of Gender-Affirming Hormone Therapy

Most studies attempting to address the health care needs of the millions of transgender, nonbinary, and/or gender-diverse (TNG) individuals rely on human subjects, overlooking the benefits of translational research in animal models. Researchers have identified many ways in which gonadal steroid hormones regulate neuronal gene expression, connectivity, activity, and function across the brain to control behavior. However, these discoveries primarily benefit cisgender populations. Research into the effects of exogenous hormones such as estradiol, testosterone, and progesterone has a direct translational benefit for TNG individuals on gender-affirming hormone therapies (GAHTs). Despite this potential, endocrinological health care for TNG individuals remains largely unimproved. Here, we outline important areas of translational research that could address the unique health care needs of TNG individuals on GAHT. We highlight key biomedical questions regarding GAHT that can be investigated using animal models. We discuss how contemporary research fails to address the needs of GAHT users and identify equitable practices for cisgender scientists engaging with this work. We conclude that if necessary and important steps are taken to address these issues, translational research on GAHTs will greatly benefit the health care outcomes of TNG people.

Sex differences in peripheral monoamine transmitter and related hormone levels in chronic stress mice with a depression-like phenotype

Backgrounds

Chronic stress could induce depression-like phenotype in animal models. Previous data showed that sex differences exist after chronic stress model establishment, however, the detailed information about the difference of blood biochemical indexes is not clear. In this study, we aim to supply comparison of monoamine transmitters and related hormone markers in serum between male and female depressed mice, and in order to better understand the sex difference in transmitters and hormone levels in depression occurrence and development.

Methods

Sixty C57BL/6 mice (both male and female) were divided into two groups by gender. Same gender mice were then divided randomly into the non-treated control group and chronic stress group which was exposed to 8 weeks of chronic unpredictable mild stress (CUMS). Depression-like behavior was assessed with open-field test and sucrose preference test. Blood sample was collected and monoamine transmitter and related hormone in serum were measured by ELISA.

Results

The depression-like phenotype mice model was established successfully after 8 weeks of chronic stress. The locomotion activity scores in male stressed mice declined more than that in female stressed mice, while the exploratory behavior scores in female stressed mice declined more than that in male stressed mice. Compared to non-treated control group mice, mice in the chronic stress group in response to stress showed greater declines in monoamine transmitters (5-HT, dopamine, norepinephrine) and sex hormones (androgen, estrogen, oxytocin and prolactin), while stress hormones (adrenaline, corticosterone and ACTH) were significantly increased. The decrease of norepinephrine, androgen and estrogen in female stressed mice was greater than in male stressed mice, whereas the 5-HT and oxytocin in male stressed mice decreased more than in female stressed mice, and the corticosterone in male stressed mice increased more than in female stressed mice.

Conclusion

Sex differences of monoamine transmitter and related hormone levels in serum occurred in chronic stress induced depression-like phenotype mice model. It may provide a useful reference to guide precise antidepressant treatment in different gender population in clinical care.

Mifepristone's effects on depression- and anxiety-like behavior in rodents

Mifepristone is a non-selective progesterone (PR), glucocorticoid (GR), and androgen receptor (AR) antagonist with antidepressant and anxiolytic effects. The dose and duration of mifepristone administration vary in rodent preclinical studies to evaluate depression-like and anxiety-like behavior. This review summarizes the findings so far and attempts to reconcile some of the differences in the results. While a few studies assessed basal depression- and anxiety-like behavior, several studies have used mifepristone in conjunction with stress, corticosterone/dexamethasone (after adrenalectomy), or progesterone administration. The effect of mifepristone on depression-like behavior appears to depend not only on the dose and duration of administration but also on the intensity or type of stress. In addition, the anxiolytic effects may depend on the species and strain of the experimental animals. More reports assess antidepressant-like or anxiolytic-like effects following acute than chronic administration. These effects are dependent on the paradigms and the nature of stressors. Most mifepristone studies implicate the role of GRs, yet only two reports have confirmed its role using a genetic approach, whereas none implicate the role of PRs/ARs. There are several novel selective GR antagonists whose effects on depression- and anxiety-like behavior are yet to be studied. Future studies could aim to confirm the role of GRs and evaluate the contribution of PRs/ARs to the effects of mifepristone. Such studies will contribute to a better understanding of depression, anxiety, and other mood disorders and develop novel strategies, particularly for treatment-resistant conditions.

Synaptic plasticity and depression: the role of miRNAs dysregulation

BACKGROUND

MicroRNAs (miRNAs) have been recently shown to exert several functional roles in the development and function of neurons. Moreover, numerous miRNAs are present in high abundance in presynaptic and postsynaptic sites regulating synaptic plasticity and activity through different mechanisms.

METHODS

We searched PubMed and Google Scholar databases with key words "Synaptic plasticity", "miRNA" and "major depressive disorder.

RESULTS

Synaptic plasticity has an essential role in the ability of the brain to integrate transitory experiences into constant memory traces. Thus, it participates in the development of neuropsychiatric diseases such as major depressive disorder (MDD). Most notably, MDD-related alterations in synaptic function have been found to be closely related with abnormal expression of miRNAs.

CONCLUSIONS

Several miRNAs such as miR-9-5p, miR-204-5p, miR-128-3, miR-26a-3p, miR-218, miR-22-3p, miR-124-3p, miR-136-3p, miR-154-5p, miR-323a-3p, miR-425-5p, miR-34a, miR-137, miR-204-5p, miR-99a, miR-134, miR-124-3p and miR-3130-5p have been shown to be involved in the regulation of synaptic plasticity in the context of MDD. In the current review, we elaborate the role of miRNAs in regulation of this important neuronal feature in MDD.

Influence of Testosterone depletion on Neurotrophin-4 in Hippocampal synaptic plasticity and its effects on learning and memory

Sex steroids are neuromodulators that play a crucial role in learning, memory, and synaptic plasticity, providing circuit flexibility and dynamic functional connectivity in mammals. Previous studies indicate that testosterone is crucial for neuronal functions and required further investigation on various frontiers. However, it is surprising to note that studies on testosterone-induced NT-4 expression and its influence on synaptic plasticity and learning and memory moderation are scanty. The present study is focused on analyzing the localized influence of neurotrophin-4 (NT4) on hippocampal synaptic plasticity and associated moderation in learning and memory under testosterone deprivation. Adult Wistar albino rats were randomly divided into various groups, control (Cont), orchidectomy (ORX), orchidectomy + testosterone supplementation (ORX+T) and control + testosterone (Cont+T). After two weeks, the serum testosterone level was undetectable in ORX rats. The behavioural assessment showed a decline in the learning ability of ORX rats with increased working and reference memory errors in the behavioural assessment in the 8-arm radial maze. The mRNA and protein expressions of NT-4 and androgen receptors were significantly reduced in the ORX group. In addition, there was a decrease in the number of neuronal dendrites in Golgi-Cox staining. These changes were not seen in ORX+T rats with improved learning behaviour. Indicating that testosterone exerts its protective effect on hippocampal synaptic plasticity through androgen receptor-dependent neurotrophin-4 regulation in learning and memory upgrade.

Androgens and Their Role in Regulating Sex Differences in the Hypothalamic/Pituitary/Adrenal Axis Stress Response and Stress-Related Behaviors

Androgens play a pivotal role during development. These gonadal hormones and their receptors exert organizational actions that shape brain morphology in regions controlling the stress regulatory systems in a male-specific manner. Specifically, androgens drive sex differences in the hypothalamic/pituitary/adrenal (HPA) axis and corresponding hypothalamic neuropeptides. While studies have examined the role of estradiol and its receptors in sex differences in the HPA axis and associated behaviors, the role of androgens remains far less studied. Androgens are generally thought to modulate the HPA axis through the activation of androgen receptors (ARs). They can also impact the HPA axis through reduction to estrogenic metabolites that can bind estrogen receptors in the brain and periphery. Such regulation of the HPA axis stress response by androgens can often result in sex-biased risk factors for stress-related disorders, such as anxiety and depression. This review focuses on the biosynthesis pathways and molecular actions of androgens and their nuclear receptors. The impact of androgens on hypothalamic neuropeptide systems (corticotropin-releasing hormone, arginine vasopressin, oxytocin, dopamine, and serotonin) that control the stress response and stress-related disorders is discussed. Finally, this review discusses potential therapeutics involving androgens (androgen replacement therapies, selective AR modulator therapies) and ongoing clinical trials.

MicroRNAs, Multiple Sclerosis, and Depression

Multiple sclerosis (MS) is a chronic disease of the central nervous system that affects the brain and spinal cord. There are several disease courses in MS including relapsing–remitting MS (RRMS), primary progressive MS (PPMS), and secondary progressive MS (SPMS). Up to 50% of MS patients experience depressive disorders. Major depression (MD) is a serious comorbidity of MS. Many dysfunctions including neuroinflammation, peripheral inflammation, gut dysbiosis, chronic oxidative and nitrosative stress, and neuroendocrine and mitochondrial abnormalities may contribute to the comorbidity between MS and MD. In addition to these actions, medical treatment and microRNA (miRNA) regulation may also be involved in the mechanisms of the comorbidity between MS and MD. In the study, I review many common miRNA biomarkers for both diseases. These common miRNA biomarkers may help further explore the association between MS and MD.

Therapeutic Targets and Mechanism of Xingpi Jieyu Decoction in Depression: A Network Pharmacology Study

Background

Depression is a common mental disease that lacks effective therapeutic drugs with good curative effects and few adverse reactions. Traditional Chinese medicine (TCM) has the advantages of multiple components, multiple channels, and fewer adverse reactions in the treatment of depression. Although Xingpi Jieyu Decoction (XPJYD) demonstrates a good therapeutic effect on depression, the pharmacological mechanism underlying its antidepressant effect is still unclear.

Methods

We used a network pharmacology strategy, including the construction and analysis of a complex drug-disease network, to explore the complex mechanism of XPJYD treatment of depression. In addition, molecular docking technology was used to preliminarily study the binding ability of the potential active components and core therapeutic targets of XPJYD.

Results

The network pharmacology results showed 42 targets of XPJYD that are involved in depression. PPI network analysis demonstrated that the top 10 core targets were AKT1, VEGFA, MAPK8, FOS, ESR1, NR3C1, IL6, HIF1A, NOS3, and AR. The molecular docking results showed that the binding energies of beta sitosterol with AR, FOS, AKT1, VEGFA, NR3C1, and NOS3 were less than −7.0 kcal·mol⁻¹, indicating a good docking effect. The GO enrichment analysis results showed that the XPJYD antidepression mechanism mainly involves the following biological processes such as apoptotic signaling pathway, cellular response to lipid, inflammatory response, and others. The KEGG analysis results indicated that XPJYD may regulate 13 pathways such as PI3K-Akt signaling pathway and estrogen signaling pathway in the treatment of depression.

Conclusions

This study reflects the characteristics of the mechanism of action by which XPJYD treats depression, which includes multiple components, multiple targets, and multiple pathways, and provides a biological basis for further verification and a novel perspective for drug discovery in depression.

A Combined Network Pharmacology and Molecular Docking Approach to Investigate Candidate Active Components and Multitarget Mechanisms of Hemerocallis Flowers on Antidepressant Effect

Objective

The purpose of our research is to systematically explore the multiple mechanisms of Hemerocallis fulva Flowers (HF) on depressive disorder (DD).

Methods

The components of HF were searched from the literature. The targets of components were obtained from PharmMapper. After that, Cytoscape software was used to build a component-target network. The targets of DD were collected from DisGeNET, PharmGKB, TTD, and OMIM. Protein-protein interactions (PPIs) among the DD targets were executed to screen the key targets. Afterward, the GO and KEGG pathway enrichment analysis were performed by the KOBAS database. A compound-target-KEGG pathway network was built to analyze the key compounds and targets. Finally, the potential active substances and targets were validated by molecular docking.

Results

A total of 55 active compounds in HF, 646 compound-related targets, and 527 DD-related targets were identified from public databases. After treated with PPI, 219 key targets of DD were acquired. The gene enrichment analysis suggested that HF probably benefits DD patients by modulating pathways related to the nervous system, endocrine system, amino acid metabolism, and signal transduction. The network analysis showed the critical components and targets of HF on DD. Results of molecular docking increased the reliability of this study.

Conclusions

It predicted and verified the pharmacological and molecular mechanism of HF against DD from a holistic perspective, which will also lay a foundation for further experimental research and rational clinical application of DD.

Depression and Vegetarians: Association between Dietary Vitamin B6, B12 and Folate Intake and Global and Subcortical Brain Volumes

Deficiency of vitamin B6 and vitamin B12, mostly in vegetarians, is found to be associated with depression and adverse neurological function. We investigated whether vitamin B6, B12, and folate have an effect on brain structure, especially among depressed people who follow a specific diet. The study sample comprised 9426 participants from the UK Biobank cohort with a mean age of 62.4 years. A generalized linear model controlling for age, sex, body mass index, ethnicity, town send deprivation index, educational qualification, smoking, and alcohol intake was used to test the association between study groups and structural brain volumes. Depression was more prevalent, and intake of vitamin B6 and B12 was lower among vegetarians, while non-vegetarians had a lower intake of folate. Overall, no significant association was observed between vitamin B6, B12, and folate intakes and both global and subcortical brain volumes among participants with depression. However, vitamin B12 intake was positively associated with right pallidum among non-depressed participants, and a significant interaction between vitamin B12 intake and depression status on the right pallidum was observed. Also, a significant interaction between folate intake and depression status on grey matter (GM) volume and left thalamus was observed. Upon diet stratification, folate intake is associated with total brain volume and GM volume among vegetarians with depression. Furthermore, no significant associations were observed for subcortical regions. Our findings suggest that dietary intake of vitamin B6 and B12 might have an effect on brain structure. Vegetarians, particularly those who suffer from depression may benefit from supplementing their diets with vitamins B6, B12, and folate to ensure brain health. Further studies, especially with a larger sample size and longitudinal design, are needed to confirm these findings.

Changes in Hippocampal Androgen Receptor Density and Behavior in Sprague-Dawley Male Rats Exposed to a Low-Pressure Blast Wave

Objective

The purpose of this study was to examine the effect of exposure of a low-intensity blast wave on androgen receptor (AR) density in the hippocampus and the potential influence on behavioral and cognitive responses.

Methods

Sprague-Dawley rats were randomly assigned to either a blast exposed group (n = 27) or an unexposed (control) group (n = 10). Animals were treated identically, except that rats within the control group were not exposed to any of the characteristics of the blast wave. Behavior measures were conducted on day seven post-exposure. The rats were initially assessed in the elevated plus maze followed by the acoustic startle response paradigm. Spatial memory performance using the Morris water-maze test was assessed at 8-days post-exposure, for seven consecutive days. Following all behavioral tests AR immunofluorescence staining was performed in different hippocampal subregions.

Results

A significant elevation in anxiety index (p < 0.001) and impaired learning (p < 0.015) and spatial memory (p < 0.0015) were noted in exposed rats. In addition, a significant attenuation of the AR was noted in the CA1 (p = 0.006) and dentate gyrus (p = 0.031) subregions of the hippocampus in blast exposed animals. Correlational analyses revealed significant associations between AR and both anxiety index (r = -.36, p = 0.031) and memory (r = -0.38, p = 0.019).

Conclusions

The results of this study demonstrate that exposure to a low-pressure blast wave resulted in a decrease in AR density, which was associated with significant behavioral and cognitive changes.

Effect of chronic stress on expression and secretion of seminal vesicle proteins in adult rats

Chronic stress (CS) is known to affect men's health especially fertility by reducing semen quality. Although the effects of CS on testicular function and sperm parameters are documented, changes of substances and secreting proteins in the seminal vesicle (SV) have never been reported. This study aimed to demonstrate the alterations of contents and expressions of proteins in seminal vesicle fluid (SVF) under CS. Fourteen adult rats were divided into control and CS groups (n = 7/each). Control rats were not exposed to stressor, while the CS animals were immobilised by restraint cage (4 hr/day) and followed by forced swimming (15 min/day) for consecutive 60 days. Biochemical substances and malondialdehyde (MDA) level in SVF were examined. Expressions of heat-shock protein 70 (Hsp70), caspases (Casp) 3 and 9, and tyrosine-phosphorylated (TyrPho) proteins were investigated in seminal vesicle tissue (SVT) and SVF. It was found that CS caused reductions of seminal epithelial height and secreted substance levels. Significantly, MDA levels in SVF and expressions of Hsp70, Casp and TyrPho proteins were increased in of CS animals. It was concluded that CS affected seminal secretion. Low quality of CS seminal plasma may associate with increase of MDA and expressions of secreted proteins.

Roles for androgens in mediating the sex differences of neuroendocrine and behavioral stress responses

Estradiol and testosterone are powerful steroid hormones that impact brain function in numerous ways. During development, these hormones can act to program the adult brain in a male or female direction. During adulthood, gonadal steroid hormones can activate or inhibit brain regions to modulate adult functions. Sex differences in behavioral and neuroendocrine (i.e., hypothalamic pituitary adrenal (HPA) axis) responses to stress arise as a result of these organizational and activational actions. The sex differences that are present in the HPA and behavioral responses to stress are particularly important considering their role in maintaining homeostasis. Furthermore, dysregulation of these systems can underlie the sex biases in risk for complex, stress-related diseases that are found in humans. Although many studies have explored the role of estrogen and estrogen receptors in mediating sex differences in stress-related behaviors and HPA function, much less consideration has been given to the role of androgens. While circulating androgens can act by binding and activating androgen receptors, they can also act by metabolism to estrogenic molecules to impact estrogen signaling in the brain and periphery. This review focuses on androgens as an important hormone for modulating the HPA axis and behaviors throughout life and for setting up sex differences in key stress regulatory systems that could impact risk for disease in adulthood. In particular, impacts of androgens on neuropeptide systems known to play key roles in HPA and behavioral responses to stress (corticotropin-releasing factor, vasopressin, and oxytocin) are discussed. A greater knowledge of androgen action in the brain is key to understanding the neurobiology of stress in both sexes.