Estrogen regulates the development of brain-derived neurotrophic factor mRNA and protein in the rat hippocampus

Sex-controlled differences in sertraline and citalopram efficacies in major depressive disorder: a randomized, double-blind trial

To investigate the response to antidepressants while controlling for sex, which has been controversial, 92 outpatient males and females with major depressive disorder were assigned to sertraline (100 mg/day) or citalopram (40 mg/day) in two strata and were assessed using Hamilton depression rating scale (HDRS) scores and brain-derived neurotrophic factor (BDNF), interleukin (IL)-6 and cortisol serum levels in this 8-week, randomized, parallel-group, double-blind clinical trial. Data of 40 sertraline and 40 citalopram recipients with equal representation of males and females assigned to each medication were analyzed, while their baseline characteristics were not statistically different ( P  > 0.05). There were no significant differences between sertraline and citalopram recipients in outcome changes ( P  > 0.05), all of which indicated improvement, but a significant time-treatment-sex interaction effect in BDNF levels was observed ( P  = 0.035). Regarding this, subgroup analyses illustrated a significantly greater increase in male BDNF levels following sertraline treatment ( P  = 0.020) with a moderate to large effect size (Cohen's d = 0.76 and ). Significant associations were observed between percentage changes in IL-6 levels and BDNF levels in sertraline recipients ( P  = 0.033) and HDRS scores in citalopram recipients ( P  < 0.001). Sex was an effect modifier in BDNF alterations following sertraline and citalopram administration. Further large-scale, high-quality, long-term studies are recommended.

B cells upregulate NMDARs, respond to extracellular glutamate, and express mature BDNF to protect the brain from ischemic injury

Following stroke, B cells enter brain regions outside of the ischemic injury to mediate functional recovery. Although B cells produce neurotrophins that support remote plasticity, including brain-derived neurotrophic factor (BDNF), it remains unclear which signal(s) activate B cells in the absence of infarct-localized pro-inflammatory cues. Activation of N-methyl-d-aspartate (NMDA)-type receptor (NMDAR) subunits on neurons can upregulate mature BDNF (mBDNF) production from a pro-BDNF precursor, but whether this occurs in B cells is unknown. We identified GluN2A and GluN2B NMDAR subunits on B cells that respond to glutamate and mediate nearly half of the glutamate-induced Ca2+ responses in activated B cell subsets. Ischemic stroke recruits GluN2A+ B cells into the ipsilesional hemisphere and both stroke and neurophysiologic levels of glutamate regulate gene and surface expression. Regardless of injury, pro-BDNF+ B cells localize to spleen/circulation whereas mBDNF+ B cells localize to the brain, including in aged male and female mice. We confirmed B cell-derived BDNF was required for in vitro and in vivo B cell-mediated neuroprotection. Lastly, GluN2A, GluN2B, glutamate-induced Ca2+ responses, and BDNF expression were all clinically confirmed in B cells from healthy donors, with BDNF+ B cells present in post-stroke human parenchyma. These data suggest that B cells express functional NMDARs that respond to glutamate, enhance NMDAR signaling with activation, and upregulate mature BDNF expression within the brain. This study identifies potential glutamate-induced neurotrophic roles for B cells in the brain; an immune response to neurotransmitters unique from established pro-inflammatory stimuli and relevant to any CNS-localized injury or disease.

Exercise-induced plasma mature brain-derived neurotrophic factor elevation in children, adolescents and adults: influence of age, maturity and physical activity

Brain-derived neurotrophic factor (BDNF) is a neurotrophin that plays a central role in neuronal health. BDNF exists in two primary isoforms, the mature form (mBDNF) and its precursor (proBDNF), with opposing downstream effects on neuronal function. The positive effect of exercise on plasma levels of the BDNF isoforms has been extensively studied in adults. However, equivalent investigations are lacking in children and adolescents. Twenty healthy children (9-12 years old), 19 adolescents (13-17 years old) and 39 adults (23-49 years old) donated venous blood before and after a 45-minute run. Platelet-poor plasma was analysed for pro- and mBDNF using an enzyme-linked immunosorbent assay. Maximal oxygen uptake and anthropometric data were assessed in all participants, while Tanner stage, circulating sex hormones and accelerometry-based activity level were assessed in children and adolescents only. We found that children, adolescents and adults have similar circulating levels of plasma pro- and mBDNF at rest. For children and adolescents, resting levels of mBDNF correlated with average time spent in vigorous activity. In response to the acute endurance exercise intervention, mBDNF increased in all age groups, but the greatest rise in mBDNF was seen in adults. The acute endurance exercise did not affect proBDNF levels. Our results demonstrate that plasma mBDNF levels, but not proBDNF, increase following endurance exercise in all age groups, with a greater effect in adults. We also show that high-intensity physical activity, but not underlying fitness, is contributing to sustained elevated mBDNF levels. KEY POINTS: We show that in children and adolescents, regular vigorous physical activity is key to increased basal levels of plasma mature brain-derived neurotrophic factor (mBDNF), a factor linked to neuroplasticity and brain health. The ability to elevate mBDNF through exercise is present across all age groups, with the greatest increase in adults. The mBDNF response to physical exercise seems to be independent of underlying physical fitness. Our findings suggest that basal plasma mBDNF levels may reflect the cumulative effects of repeated exercise rather than an individual's overall physical fitness.

Sex Steroids and Brain-Derived Neurotrophic Factor Interactions in the Nervous System: A Comprehensive Review of Scientific Data

Sex steroids and the neurotrophin brain-derived neurotrophic factor (BDNF) participate in neural tissue formation, phenotypic differentiation, and neuroplasticity. These processes are essential for the health and maintenance of the central nervous system.

AIM

The aim of our review is to elucidate the interaction mechanisms between BDNF and sex steroids in neuronal function.

METHOD

A series of searches were performed using Mesh terms for androgen/receptors, estrogen/receptors, and BDNF/receptors, and a collection of the scientific data available on PubMed up to February 2025 about mechanical interactions between BDNF and sex steroids was included in this literature review.

DISCUSSION

This review discussed the influence of sex steroids on the formation and/or maintenance of neural circuits via different mechanisms, including the regulation of BDNF expression and signaling. Estrogens exert a time- and region-specific effect on BDNF synthesis. The nuclear estrogen receptor can directly regulate BDNF expression, independently of the presence of estrogen, in neuronal cells, whereas progesterone and testosterone upregulate BDNF expression via their specific nuclear receptors. In addition, testosterone has a positive effect on BDNF release by glial cells, which lack androgen receptors.

Estrogen Regulates Mitochondrial Activity Through Inducing Brain-Derived Neurotrophic Factor Expression in Skeletal Muscle

Estrogen is an essential hormone for the development and functional activities of reproductive organs. Recent studies showed that estrogen signaling is also an important regulator of lipid and glucose metabolism in a number of tissues, but the molecular mechanism is not fully understood. We report here that estrogen is a stimulator of brain-derived neurotrophic factor (BDNF) synthesis in the skeletal muscle. Estradiol (E2), but not testosterone, induces a dose- and time-dependent BDNF production in cultured myotubes. Estrogen depletion in ovariectomized mice significantly reduced Bdnf expression in the glycolytic myofibers, which could be rescued after E2 administration. Mechanistically, E2 stimulation triggered the tethering of estrogen receptor (ER) α, but not ERβ, to the estrogen-responsive element on promoter VI of the Bdnf gene in skeletal muscle. When Bdnf production was inhibited by shRNA in C2C12 myotubes, E2-induced mitochondria activation and pyruvate dehydrogenase kinase 4 expressions were jeopardized. Collectively, our results demonstrate that BDNF is an underrecognized effector of estrogen in regulating mitochondrial activity and fuel metabolism in the skeletal muscle.

New Insights into Contradictory Changes in Brain-Derived Neurotrophic Factor (BDNF) in Rodent Models of Posttraumatic Stress Disorder (PTSD)

Post-traumatic stress disorder (PTSD) is a neuropsychiatric disorder that may develop after experiencing traumatic events. Preclinical studies use various methods to induce PTSD-like models such as fear-conditioning, single-prolonged stress (SPS), restraint stress, and social defeat. Brain-derived neurotrophic factor (BDNF) is a crucial neurotrophin in mood regulation. Evidence shows BDNF changes in different neuropsychiatric disorders particularly PTSD. This review examined BDNF alterations in preclinical rodent models of PTSD where we demonstrated a wide range of paradoxical changes in BDNF. We found that the fear-conditioning model produced the most inconsistent alterations in BDNF, and suggest that conclusions drawn from these changes be approached with caution. We suggest that BDNF maladaptive changes in social defeat and restraint stress models may be related to the duration of stress, while the SPS model appears to have more consistent results. Ultimately, we propose that evaluating BDNF alterations in the process of treating PTSD symptoms may not be a reliable factor.

A Recent Update on the Role of Estrogen and Progesterone in Alzheimer's Disease

Alzheimer's disease (AD), one of the most prevalent neurodegenerative disease responsible for 60%-80% dementia cases globally. The disease is more prevalent among elder females. Female reproductive hormones are found to be essential for cellular activities in brain. The physiological role of neurotrophins and sex hormones in hippocampal region during neurogenesis and neuron differentiation was studied as well. In addition to triggering cellular pathways, estrogen and progesterone carry out a number of biological processes that lead to neuroprotection. They might have an impact on learning and memory. One of estrogen's modest antioxidant properties is its direct scavenging of free radicals. The neurotrophic effect of estrogen and progesterone can be explained by their ability to rise the expression of the brain-derived neurotrophic factor (BDNF) mRNA. Additionally, they have the ability to degrade beta-amyloid and stop inflammation, apoptotic neuronal cell death, and tau protein phosphorylation. To enhance their neuroprotective action, various cross-talking pathways in cells that are mediated by estrogen, progesterone, and BDNF receptors. This include signaling by mitogen-activated protein kinase/extracellular regulated kinase, phosphatidylinositol 3-kinase/protein kinase B, and phospholipase/protein kinase C. Clinical research to establish the significance of these substances are fragmented, despite publications claiming a lower prevalence of AD when medication is started before menopause. This review article emphasizes an update on the role of estrogen, and progesterone in AD.

Does brain-derived neurotrophic factor play a role in the association between maternal prenatal mental health and neurodevelopment in 2-year-old children?

OBJECTIVE

To evaluate the role of brain-derived neurotrophic factor (BDNF)-a crucial modulator of neural development and plasticity-in the association between prenatal maternal anxiety, depression, and perceived stress and child neurodevelopment in a prospective cohort study.

METHODS

We included 526 eligible mother-child pairs from the Shanghai Birth Cohort in the study. Maternal mental health was assessed at mid-pregnancy using Zung's Self-Rating Anxiety Scale, Center for Epidemiologic Studies Depression Scale, and Perceived Stress Scale. The concentration of BDNF in cord blood was measured by ELISA. The offspring neurodevelopment at 24 months of age was assessed using the Bayley Scales. Linear and non-linear regression models were used.

RESULTS

The average cord blood BDNF levels were higher in female newborns and those born via vaginal delivery, full term, and normal birth weight. Prenatal maternal anxiety (β = -0.32; 95 % CI: -0.55, -0.09), depression (β = -0.30; 95 % CI: -0.52, -0.08), and perceived stress (β = -0.41; 95 % CI: -0.71, -0.12) scores were negatively associated with social-emotional performance at 24 months of age. However, no significant associations were found between prenatal maternal anxiety, depression, or perceived stress at mid-pregnancy and cord blood BDNF levels, as well as between cord blood BDNF levels and child neurodevelopment.

LIMITATIONS

Maternal mental health at different timepoints during pregnancy and generalizability of the results warrant further assessment.

CONCLUSIONS

Prenatal mental health was not associated with cord blood BDNF level and that BDNF may not be a mediator in the association between prenatal mental health and child neurodevelopment.

Estrogenic regulation of hippocampal inhibitory system across lifespan

Estrogens produced in peripheral tissues and locally in the brain are potent neuromodulators. The function of the hippocampus, a brain region essential for episodic memory and spatial navigation, relies on the activity of ensembles of excitatory neurons whose activity is temporally and spatially coordinated by a wide diversity of inhibitory neurons (INs) types. Over the last years, we have accumulated evidence that indicates that estrogens regulate the function of hippocampal INs through different mechanisms, including transcriptional regulation and rapid nongenomic signaling. Here, we argue that the well-documented influence of estrogens on episodic memory may be related to the actions of local and peripheral estrogens on the heterogenous populations of hippocampal INs. We discuss how physiological changes in peripheral sex hormone levels throughout lifespan may interact with local brain sources to regulate IN function at different stages of life, from early hippocampal development to the aging brain. We conclude that considering INs as mediators of sex hormone actions in the hippocampus across the healthy life span will benefit our understanding of sex-biased neurodevelopmental disorders and physiological aging.

Male autism spectrum disorder is linked to brain aromatase disruption by prenatal BPA in multimodal investigations and 10HDA ameliorates the related mouse phenotype

Male sex, early life chemical exposure and the brain aromatase enzyme have been implicated in autism spectrum disorder (ASD). In the Barwon Infant Study birth cohort (n = 1074), higher prenatal maternal bisphenol A (BPA) levels are associated with higher ASD symptoms at age 2 and diagnosis at age 9 only in males with low aromatase genetic pathway activity scores. Higher prenatal BPA levels are predictive of higher cord blood methylation across the CYP19A1 brain promoter I.f region (P = 0.009) and aromatase gene methylation mediates (P = 0.01) the link between higher prenatal BPA and brain-derived neurotrophic factor methylation, with independent cohort replication. BPA suppressed aromatase expression in vitro and in vivo. Male mice exposed to mid-gestation BPA or with aromatase knockout have ASD-like behaviors with structural and functional brain changes. 10-hydroxy-2-decenoic acid (10HDA), an estrogenic fatty acid alleviated these features and reversed detrimental neurodevelopmental gene expression. Here we demonstrate that prenatal BPA exposure is associated with impaired brain aromatase function and ASD-related behaviors and brain abnormalities in males that may be reversible through postnatal 10HDA intervention.

Analysis of the BDNF Gene rs6265 Polymorphism in a Group of Women with Alcohol Use Disorder, Taking into Account Personality Traits

It seems that BDNF has a direct influence on the brain pathways and is typically engaged during the processing of rewards. A surge in BDNF levels in the ventral tegmental area (the region from which the dopaminergic neurons of the mesocorticolimbic dopamine system originate and extend to the dorsolateral and ventromedial striatum) triggers a state of reward similar to that produced by opiates in animal studies. The aims of the study were (1) to analyze the association of the BDNF gene rs6265 polymorphism with AUD (alcohol use disorder) in women, (2) analyze personality and anxiety in alcohol-dependent and control woman, and (3) conduct an interaction analysis of rs6265 on personality, anxiety, and alcohol dependence. Our study found a notable interaction between the anxiety (trait and state), neuroticism, rs6265, and AUD. The alcohol AUD G/A genotype carriers revealed higher level of the anxiety trait (p < 0.0001) and neuroticism (p < 0.0001) compared to the control group with G/A and G/G genotypes. The alcohol use disorder subjects with the G/A genotype displayed higher levels of an anxiety state than the control group with G/A (p < 0.0001) and G/G (p = 0.0014) genotypes. Additionally, the alcohol use disorder subjects with the G/G genotype obtained lower levels of agreeability compared to the controls with G/A (p < 0.0001) and G/G (p < 0.0001) genotypes. Our study indicates that anxiety (trait and state) and neuroticism are interacting with the BDNF gene rs6265 polymorphism in alcohol-dependent women. Characteristics like anxiety (both as a trait and a state) and neuroticism could have a significant impact on the mechanism of substance dependency, particularly in females who are genetically susceptible. This is regardless of the reward system that is implicated in the emotional disruptions accompanying anxiety and depression.

TrkB-mediated neuroprotection in female hippocampal neurons is autonomous, estrogen receptor alpha-dependent, and eliminated by testosterone: a proposed model for sex differences in neonatal hippocampal neuronal injury

BACKGROUND

Neonatal hypoxia ischemia (HI) related brain injury is one of the major causes of learning disabilities and memory deficits in children. In both human and animal studies, female neonate brains are less susceptible to HI than male brains. Phosphorylation of the nerve growth factor receptor TrkB has been shown to provide sex-specific neuroprotection following in vivo HI in female mice in an estrogen receptor alpha (ERα)-dependent manner. However, the molecular and cellular mechanisms conferring sex-specific neonatal neuroprotection remain incompletely understood. Here, we test whether female neonatal hippocampal neurons express autonomous neuroprotective properties and assess the ability of testosterone (T) to alter this phenotype.

METHODS

We cultured sexed hippocampal neurons from ERα+/+ and ERα-/- mice and subjected them to 4 h oxygen glucose deprivation and 24 h reoxygenation (4-OGD/24-REOX). Sexed hippocampal neurons were treated either with vehicle control (VC) or the TrkB agonist 7,8-dihydroxyflavone (7,8-DHF) following in vitro ischemia. End points at 24 h REOX were TrkB phosphorylation (p-TrkB) and neuronal survival assessed by immunohistochemistry. In addition, in vitro ischemia-mediated ERα gene expression in hippocampal neurons were investigated following testosterone (T) pre-treatment and TrkB antagonist therapy via q-RTPCR. Multifactorial analysis of variance was conducted to test for significant differences between experimental conditions.

RESULTS

Under normoxic conditions, administration of 3 µM 7,8-DHF resulted an ERα-dependent increase in p-TrkB immunoexpression that was higher in female, as compared to male neurons. Following 4-OGD/24-REOX, p-TrkB expression increased 20% in both male and female ERα+/+ neurons. However, with 3 µM 7,8-DHF treatment p-TrkB expression increased further in female neurons by 2.81 ± 0.79-fold and was ERα dependent. 4-OGD/24-REOX resulted in a 56% increase in cell death, but only female cells were rescued with 3 µM 7,8-DHF, again in an ERα dependent manner. Following 4-OGD/3-REOX, ERα mRNA increased ~ 3 fold in female neurons. This increase was blocked with either the TrkB antagonist ANA-12 or pre-treatment with T. Pre-treatment with T also blocked the 7,8-DHF- dependent sex-specific neuronal survival in female neurons following 4-OGD/24-REOX.

CONCLUSIONS

OGD/REOX results in sex-dependent TrkB phosphorylation in female neurons that increases further with 7,8-DHF treatment. TrkB phosphorylation by 7,8-DHF increased ERα mRNA expression and promoted cell survival preferentially in female hippocampal neurons. The sex-dependent neuroprotective actions of 7,8-DHF were blocked by either ANA-12 or by T pre-treatment. These results are consistent with a model for a female-specific neuroprotective pathway in hippocampal neurons in response to hypoxia. The pathway is activated by 7,8-DHF, mediated by TrkB phosphorylation, dependent on ERα and blocked by pre-exposure to T.

Expression Profiles of Brain-Derived Neurotrophic Factor Splice Variants in the Hippocampus of Alzheimer's Disease Model Mouse

Dysregulation of brain-derived neurotrophic factor (BDNF) has been implicated in Alzheimer's disease (AD). In this study, we investigated the temporal dynamics of BDNF expression in the hippocampus of 5xFAD mice, an AD model, focusing on sex and age differences and Bdnf mRNA splice variants. At 3 months of age, female wild-type (WT) mice exhibited significantly higher Bdnf mRNA levels compared to males. However, this difference was abolished in female 5xFAD mice. At 6 months of age, no sex differences in Bdnf mRNA levels were observed in WT mice, and the levels tended to be lower in female 5xFAD mice. Additionally, a significant decrease in the mRNA levels of full-length tropomyosin-related kinase B (TrkB), a BDNF receptor, was found in female 5xFAD mice at 6 months, while mRNA levels of the truncated TrkB were increased in both male and female 5xFAD mice. Specifically, among the Bdnf mRNA splice variants, the levels of Bdnf exon IIA-IX, exon IIB-IX, exon IIC-IX, and exon IXA mRNA were significantly higher in female WT mice compared to male WT mice at 3 months, but this difference was lost in female 5xFAD mice. These findings suggest that the expression of specific Bdnf splice variants would be maintained at higher levels in the hippocampus of young female mice than in males but may be disrupted in AD model mice. Our study may provide insights into the relationship between sex differences in AD onset and BDNF expression.

Parvalbumin as a sex-specific target in Alzheimer's disease research - A mini-review

Alzheimer's disease (AD) is the most common form of dementia, and both the incidence of this disease and its associated cognitive decline disproportionally effect women. While the etiology of AD is unknown, recent work has demonstrated that the balance of excitatory and inhibitory activity across the brain may serve as a strong predictor of cognitive impairments in AD. Across the cortex, the most prominent source of inhibitory signalling is from a class of parvalbumin-expressing interneurons (PV+). In this mini-review, the impacts of sex- and age-related factors on the function of PV+ neurons are examined within the context of vulnerability to AD pathology. These primary factors of influence include changes in brain metabolism, circulating sex hormone levels, and inflammatory response. In addition to positing the increased vulnerability of PV+ neurons to dysfunction in AD, this mini-review highlights the critical importance of presenting sex stratified data in the study of AD.

Endocrine-Disrupting Chemicals and Hippocampal Development: The Role of Estrogen and Androgen Signaling

Hormones are important regulators of key processes during fetal brain development. Thus, the developing brain is vulnerable to the action of chemicals that can interfere with endocrine signals. Epidemiological studies have pointed toward sexually dimorphic associations between neurodevelopmental outcomes, such as cognitive abilities, in children and prenatal exposure to endocrine-disrupting chemicals (EDCs). This points toward disruption of sex steroid signaling in the development of neural structures underlying cognitive functions, such as the hippocampus, an essential mediator of learning and memory processes. Indeed, during development, the hippocampus is subjected to the organizational effects of estrogens and androgens, which influence hippocampal cell proliferation, differentiation, dendritic growth, and synaptogenesis in the hippocampal fields of Cornu Ammonis and the dentate gyrus. These early organizational effects correlate with a sexual dimorphism in spatial cognition and are subject to exogenous chemical perturbations. This review summarizes the current knowledge about the organizational effects of estrogens and androgens on the developing hippocampus and the evidence for hippocampal-dependent learning and memory perturbations induced by developmental exposure to EDCs. We conclude that, while it is clear that sex hormone signaling plays a significant role during hippocampal development, a complete picture at the molecular and cellular levels would be needed to establish causative links between the endocrine modes of action exerted by EDCs and the adverse outcomes these chemicals can induce at the organism level.

Short-Term Irisin Treatment Enhanced Neurotrophin Expression Differently in the Hippocampus and the Prefrontal Cortex of Young Mice

As a result of physical exercise, muscle releases multiple exerkines, such as "irisin", which is thought to induce pro-cognitive and antidepressant effects. We recently demonstrated in young healthy mice the mitigation of depressive behaviors induced by consecutive 5 day irisin administration. To understand which molecular mechanisms might be involved in such effect, we here studied, in a group of mice previously submitted to a behavioral test of depression, the gene expression of neurotrophins and cytokines in the hippocampus and prefrontal cortex (PFC), two brain areas frequently investigated in the depression pathogenesis. We found significantly increased mRNA levels of nerve growth factor (NGF) and fibroblast growth factor 2 (FGF-2) in the hippocampus and brain-derived growth factor (BDNF) in the PFC. We did not detect a difference in the mRNA levels of interleukin 6 (IL-6) and IL-1β in both brain regions. Except for BDNF in the PFC, two-way ANOVA analysis did not reveal sex differences in the expression of the tested genes. Overall, our data evidenced a site-specific cerebral modulation of neurotrophins induced by irisin treatment in the hippocampus and the PFC, contributing to the search for new antidepressant treatments targeted at single depressive events with short-term protocols.

The Interaction Between Brain-Derived Neurotrophic Factor Levels and Alcohol Consumption, Sleep Disturbance and Sex-Hormones in Alcohol Use Disorders

AIMS

Brain-derived neurotrophic factor (BDNF) levels may be associated with alcohol use disorders (AUD) and alcohol consumption, correlate with sleep disturbance and be influenced by sex differences and sex hormones. These associations have not been examined in a single sample accounting for all these factors.

METHODS

Data from 190 participants (29.4% female) with AUD were utilized. Sleep quality, craving intensity, depression, anxiety and alcohol consumption were assessed using the Pittsburgh Sleep Quality Index (PSQI), Penn Alcohol Craving Scale (PACS), Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7) and Timeline Follow Back for 90 days(TLFB 90). Inventory of Drug Taking Situations (IDTS) assessed the tendency to drink in positive/negative emotional states. Serum BDNF (sBDNF) and plasma sex hormones (estrogen, progesterone, testosterone, FSH and SHBG) were measured. Pearson correlation analyses were used to examine the association between sBDNF and these measures in the entire sample and in men and women separately. Higher order interaction effects between these factors were evaluated for their association with sBDNF using a backward selection model.

RESULTS

No significant correlations between sBDNF levels and sex hormones, PSQI, PHQ-9, PACS, IDTS scores and alcohol consumption were found (all P-values > 0.05). sBDNF levels were negatively correlated with GAD-7 scores in men (r = -0.1841; P = 0.03). When considering all quadratic and two-way interactions among PSQI, PHQ-9, GAD-7, mean and max drinks/day, number of drinking days, heavy drinking days, and sex no higher order moderating effects of sBDNF levels were found.

CONCLUSION

Our study revealed no significant associations between sBDNF and alcohol measures, sleep, depression and sex hormones suggesting limited utility as a biomarker.

Impact of endocrine disruptors from mother's diet on immuno-hormonal orchestration of brain development and introduction of the virtual human twin tool

Diet has long been known to modify physiology during development and adulthood. However, due to a growing number of manufactured contaminants and additives over the last few decades, diet has increasingly become a source of exposure to chemicals that has been associated with adverse health risks. Sources of food contaminants include the environment, crops treated with agrochemicals, inappropriate storage (e.g., mycotoxins) and migration of xenobiotics from food packaging and food production equipment. Hence, consumers are exposed to a mixture of xenobiotics, some of which are endocrine disruptors (EDs). The complex interactions between immune function and brain development and their orchestration by steroid hormones are insufficiently understood in human populations, and little is known about the impact on immune-brain interactions by transplacental fetal exposure to EDs via maternal diet. To help to identify the key data gaps, this paper aims to present (a) how transplacental EDs modify immune system and brain development, and (b) how these mechanisms may correlate with diseases such as autism and disturbances of lateral brain development. Attention is given to disturbances of the subplate, a transient structure of crucial significance in brain development. Additionally, we describe cutting edge approaches to investigate the developmental neurotoxicity of EDs, such as the application of artificial intelligence and comprehensive modelling. In the future, highly complex investigations will be performed using virtual brain models constructed using sophisticated multi-physics/multi-scale modelling strategies based on patient and synthetic data, which will enable a greater understanding of healthy or disturbed brain development.

Anxiolytic- and antidepressant-like effects of Bacillus coagulans Unique IS-2 mediate via reshaping of microbiome gut-brain axis in rats

BACKGROUND

Due to the rising cases of treatment-refractory affective disorders, the discovery of newer therapeutic approaches is needed. In recent times, probiotics have garnered notable attention in managing stress-related disorders. Herein, we examined the effect of Bacillus coagulans Unique IS-2® probiotic on anxiety- and depression-like phenotypes employing maternal separation (MS) and chronic-unpredictable mild stress (CUMS) model in rats.

METHODS

Both male and female Sprague-Dawley rats were subjected to MS + CUMS. Probiotic treatment was provided for 6 weeks via drinking water. Anxiety- and depression-like phenotypes were assessed using sucrose-preference test (SPT), forced-swimming test (FST), elevated-plus maze test (EPM), and open-field test (OFT). Blood, brain, intestine, and fecal samples were obtained for biochemical and molecular studies.

RESULTS

Stress-exposed rats drank less sucrose solution, showed increased passivity, and explored less in open-arms in SPT, FST, and EPM, respectively. These stress-generated neurobehavioral aberrations were alleviated by 6-week of Bacillus coagulans Unique IS-2 treatment. The overall locomotor activity in OFT remained unchanged. The decreased levels of BDNF and serotonin and increased levels of C-reactive protein, TNF-α, IL-1β, and dopamine, in the hippocampus and/or frontal cortex of stress-exposed rats were reversed following probiotic treatment. Administration of probiotic also restored the systemic levels of L-tryptophan, L-kynurenine, kynurenic-acid, and 3-hydroxyanthranilic acid, villi/crypt ratio, goblet-cell count, Firmicutes to Bacteroides ratio, and levels of acetate, propionate, and butyrate in fecal samples. These results indicate remodeling of the microbiome gut-brain axis in Bacillus coagulans Unique IS-2 recipient rats. However, protein levels of doublecortin, GFAP, and zona occludens in the hippocampus and occludin-immunoreactivity in the intestine remained unchanged. No prominent sex-specific changes were noted.

CONCLUSION

Anxiolytic- and antidepressant-like effects of Bacillus coagulans Unique IS-2 in MS + CUMS rat model may be mediated via reshaping the microbiome gut-brain axis.

Targeting Estrogen Signaling in the Radiation-induced Neurodegeneration: A Possible Role of Phytoestrogens

Radiation for medical use is a well-established therapeutic method with an excellent prognosis rate for various cancer treatments. Unfortunately, a high dose of radiation therapy comes with its own share of side effects, causing radiation-induced non-specific cellular toxicity; consequently, a large percentage of treated patients suffer from chronic effects during the treatment and even after the post-treatment. Accumulating data evidenced that radiation exposure to the brain can alter the diverse cognitive-related signaling and cause progressive neurodegeneration in patients because of elevated oxidative stress, neuroinflammation, and loss of neurogenesis. Epidemiological studies suggested the beneficial effect of hormonal therapy using estrogen in slowing down the progression of various neuropathologies. Despite its primary function as a sex hormone, estrogen is also renowned for its neuroprotective activity and could manage radiation-induced side effects as it regulates many hallmarks of neurodegenerations. Thus, treatment with estrogen and estrogen-like molecules or modulators, including phytoestrogens, might be a potential approach capable of neuroprotection in radiation-induced brain degeneration. This review summarized the molecular mechanisms of radiation effects and estrogen signaling in the manifestation of neurodegeneration and highlighted the current evidence on the phytoestrogen mediated protective effect against radiationinduced brain injury. This existing knowledge points towards a new area to expand to identify the possible alternative therapy that can be taken with radiation therapy as adjuvants to improve patients' quality of life with compromised cognitive function.

Hypothalamic AAV-BDNF gene therapy improves metabolic function and behavior in the Magel2-null mouse model of Prader-Willi syndrome

Individuals with Prader-Willi syndrome (PWS) display developmental delays, cognitive impairment, excessive hunger, obesity, and various behavioral abnormalities. Current PWS treatments are limited to strict supervision of food intake and growth hormone therapy, highlighting the need for new therapeutic strategies. Brain-derived neurotrophic factor (BDNF) functions downstream of hypothalamic feeding circuitry and has roles in energy homeostasis and behavior. In this preclinical study, we assessed the translational potential of hypothalamic adeno-associated virus (AAV)-BDNF gene therapy as a therapeutic for metabolic dysfunction in the Magel2-null mouse model of PWS. To facilitate clinical translation, our BDNF vector included an autoregulatory element allowing for transgene titration in response to the host's physiological needs. Hypothalamic BDNF gene transfer prevented weight gain, decreased fat mass, increased lean mass, and increased relative energy expenditure in female Magel2-null mice. Moreover, BDNF gene therapy improved glucose metabolism, insulin sensitivity, and circulating adipokine levels. Metabolic improvements were maintained through 23 weeks with no adverse behavioral effects, indicating high levels of efficacy and safety. Male Magel2-null mice also responded positively to BDNF gene therapy, displaying improved body composition, insulin sensitivity, and glucose metabolism. Together, these data suggest that regulating hypothalamic BDNF could be effective in the treatment of PWS-related metabolic abnormalities.

Gene- and Gender-Related Decrease in Serum BDNF Levels in Alzheimer's Disease

Brain-derived neurotrophic factor (BDNF) has a protective role in Alzheimer's disease (AD). Oxidative stress and inflammatory cytokines are potentially implicated in AD risk. In this study, BDNF was detected in serum of AD and mild cognitive impairment (MCI) patients and investigated in association with gene polymorphisms of BDNF (Val66Met and C270T), of some oxidative stress-related genes (FOXO3A, SIRT3, GLO1, and SOD2), and of interleukin-1 family genes (IL-1α, IL-1β, and IL-38). The APOE status and mini-mental state examination (MMSE) score were also evaluated. Serum BDNF was significantly lower in AD (p = 0.029), especially when comparing the female subsets (p = 0.005). Patients with BDNFVal/Val homozygous also had significantly lower circulating BDNF compared with controls (p = 0.010). Moreover, lower BDNF was associated with the presence of the T mutant allele of IL-1α(rs1800587) in AD (p = 0.040). These results were even more significant in the female subsets (BDNFVal/Val, p = 0.001; IL-1α, p = 0.013; males: ns). In conclusion, reduced serum levels of BDNF were found in AD; polymorphisms of the IL-1α and BDNF genes appear to be involved in changes in serum BDNF, particularly in female patients, while no effects of other gene variants affecting oxidative stress have been found. These findings add another step in identifying gender-related susceptibility to AD.

Function of brain-derived neurotrophic factor in the hypothalamus: Implications for depression pathology

Depression is a prevalent mental health disorder and is the number one cause of disability worldwide. Risk factors for depression include genetic predisposition and stressful life events, and depression is twice as prevalent in women compared to men. Both clinical and preclinical research have implicated a critical role for brain-derived neurotrophic factor (BDNF) signaling in depression pathology as well as therapeutics. A preponderance of this research has focused on the role of BDNF and its primary receptor tropomyosin-related kinase B (TrkB) in the cortex and hippocampus. However, much of the symptomatology for depression is consistent with disruptions in functions of the hypothalamus including changes in weight, activity levels, responses to stress, and sociability. Here, we review evidence for the role of BDNF and TrkB signaling in the regions of the hypothalamus and their role in these autonomic and behavioral functions associated with depression. In addition, we identify areas for further research. Understanding the role of BDNF signaling in the hypothalamus will lead to valuable insights for sex- and stress-dependent neurobiological underpinnings of depression pathology.

Arsenic Induces GSK3β-dependent p-tau, neuronal apoptosis and cognitive impairment via an interdependent hippocampal ERα and IL-1/IL-1R1 mechanism in female rats

Arsenic is an environmental contaminant with potential neurotoxicity. We previously reported that arsenic promoted hippocampal neuronal apoptosis, inducing cognitive loss. Here, we correlated it with tau pathology. We observed that environmentally relevant arsenic exposure increased tau phosphorylation and the principal tau kinase, glycogen synthase kinase-3 beta (GSK3β), in the female rat hippocampal neurons. We detected the same in primary hippocampal neurons. Since a regulated estrogen receptor (ER) level and inflammation contributed to normal hippocampal functions, we examined their levels following arsenic exposure. Our ER screening data revealed that arsenic down-regulated hippocampal neuronal ERα. We also detected an up-regulated hippocampal interleukin-1 (IL-1) and its receptor, IL-1R1. Further, co-treating arsenic with the ERα agonist, 4,4',4''-(4-Propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT), or IL-1R antagonist (IL-1Ra) resulted in reduced GSK3β and p-tau, indicating involvement of decreased ERα and increased IL-1/IL-1R1 in tau hyperphosphorylation. We then checked whether ERα and IL-1/IL-1R1 had linkage, and detected that while PPT reduced IL-1 and IL-1R1, the IL-1Ra restored ERα, suggesting their arsenic-induced interdependence. We finally correlated this pathway with apoptosis and cognition. We observed that PPT, IL-1Ra and the GSK3β inhibitor, LiCl, reduced hippocampal neuronal cleaved caspase-3 and TUNEL+ve apoptotic count, and decreased the number of errors during learning and increased the saving-memory for Y-Maze Test and retention performance for Passive avoidance test in arsenic-treated rats. Thus, our study reveals a novel mechanism of arsenic-induced GSK3β-dependent tau pathology via interdependent ERα and IL-1/IL-1R1 signaling. It also envisages the protective role of ERα agonist and IL-1 inhibitor against arsenic-induced neurotoxicity.

Multi-strain Probiotic Formulation Reverses Maternal Separation and Chronic Unpredictable Mild Stress-Generated Anxiety- and Depression-like Phenotypes by Modulating Gut Microbiome-Brain Activity in Rats

Depression is a debilitating mental disorder that affects >322 million people worldwide. Despite the availability of several antidepressant agents, many patients remain treatment refractory. A growing literature study has indicated the role of gut microbiota in neuropsychiatric disorders. Herein, we examined the psychobiotic-like activity of multi-strain probiotic formulation in maternal separation (MS) and chronic unpredictable mild stress (CUMS) models of anxiety- and depression-like phenotypes in Sprague-Dawley rats. Early- and late-life stress was employed in both male and female rats by exposing them to MS and CUMS. The multi-strain probiotic formulation (Cognisol) containing Bacillus coagulans Unique IS-2, Lactobacillus plantarum UBLP-40, Lactobacillus rhamnosus UBLR-58, Bifidobacterium lactis UBBLa-70, Bifidobacterium breve UBBr-01, and Bifidobacterium infantis UBBI-01 at a total strength of 10 billion cfu along with l-glutamine was administered for 6 weeks via drinking water. Neurobehavioral assessment was done using the forced swim test (FST), sucrose preference test (SPT), elevated plus maze (EPM), and open field test (OFT). Animals were sacrificed after behavioral assessment, and blood, brain, and intestine samples were collected to analyze the levels of cytokines, metabolites, and neurotransmitters and histology. Animals exposed to stress showed increased passivity, consumed less sucrose solution, and minimally explored the open arms in the FST, SPT, and EPM, respectively. Administration of multi-strain probiotics along with l-glutamine for 6 weeks ameliorated the behavioral abnormalities. The locomotor activity of animals in the OFT and their body weight remained unchanged across the groups. Cognisol treatment reversed the decreased BDNF and serotonin levels and increased CRP, TNF-α, and dopamine levels in the hippocampus and/or frontal cortex. Administration of Cognisol also restored the plasma levels of l-tryptophan, l-kynurenine, kynurenic-acid, and 3-hydroxyanthranilic acid; the Firmicutes-to-Bacteroides ratio; the levels of acetate, propionate, and butyrate in fecal samples; the villi/crypt ratio; and the goblet cell count, which manifested in the restoration of intestinal functions. We suggest that the multi-strain probiotic and glutamine formulation (Cognisol) ameliorated the MS + UCMS-generated anxiety- and depression-like phenotypes by reshaping the gut microbiome-brain activity in both sexes.

Arsenic Induces Differential Neurotoxicity in Male, Female, and E2-Deficient Females: Comparative Effects on Hippocampal Neurons and Cognition in Adult Rats

We earlier reported that arsenic induced hippocampal neuronal loss, causing cognitive dysfunctions in male rats. This neuronal damage mechanism involved an altered bone morphogenetic protein (BMP2)/Smad and brain-derived neurotrophic factor (BDNF)/TrkB signaling. Susceptibility to toxicants is often sex-dependent, and hence we studied the comparative effects of arsenic in adult male and female rats. We observed that a lower dose of arsenic reduced learning-memory ability, examined through passive avoidance and Y-maze tests, in male but not female rats. Again, male rats exhibited greater learning-memory loss at a higher dose of arsenic. Supporting this, arsenic-treated male rats demonstrated larger reduction in the hippocampal NeuN and %-surviving neurons, together with increased apoptosis and altered BMP2/Smad and BDNF/TrkB pathways compared to their female counterparts. Since the primary female hormone, estrogen (E2), regulates normal brain functions, we next probed whether endogenous E2 levels in females offered resistance against arsenic-induced neurotoxicity. We used ovariectomized (OVX) rat as the model for E2 deficiency. We primarily identified that OVX itself induced hippocampal neuronal damage and cognitive decline, involving an increased BMP2/Smad and reduced BDNF/TrkB. Further, these effects appeared greater in arsenic + OVX compared to arsenic + sham (ovary intact) or OVX rats alone. The OVX-induced adverse effects were significantly reduced by E2 treatment. Overall, our study suggests that adult males could be more susceptible than females to arsenic-induced neurotoxicity. It also indicates that endogenous E2 regulates hippocampal BMP and BDNF signaling and restrains arsenic-induced neuronal dysfunctions in females, which may be inhibited in E2-deficient conditions, such as menopause or ovarian failure.

Brain-derived neurotrophic factor in Alzheimer's disease and its pharmaceutical potential

Synaptic abnormalities are a cardinal feature of Alzheimer's disease (AD) that are known to arise as the disease progresses. A growing body of evidence suggests that pathological alterations to neuronal circuits and synapses may provide a mechanistic link between amyloid β (Aβ) and tau pathology and thus may serve as an obligatory relay of the cognitive impairment in AD. Brain-derived neurotrophic factors (BDNFs) play an important role in maintaining synaptic plasticity in learning and memory. Considering AD as a synaptic disorder, BDNF has attracted increasing attention as a potential diagnostic biomarker and a therapeutical molecule for AD. Although depletion of BDNF has been linked with Aβ accumulation, tau phosphorylation, neuroinflammation and neuronal apoptosis, the exact mechanisms underlying the effect of impaired BDNF signaling on AD are still unknown. Here, we present an overview of how BDNF genomic structure is connected to factors that regulate BDNF signaling. We then discuss the role of BDNF in AD and the potential of BDNF-targeting therapeutics for AD.

In utero exposure to endocrine disruptors and developmental neurotoxicity: Implications for behavioural and neurological disorders in adult life

Endocrine disrupting chemicals (EDCs) are a class of environmental toxicants that interfere with the endocrine system, resulting in developmental malformations, reproductive disorders, and alterations to immune and nervous system function. The emergence of screening studies identifying these chemicals in fetal developmental matrices such as maternal blood, placenta and amniotic fluid has steered research focus towards elucidation of in utero effects of exposure to these chemicals, as their capacity to cross the placenta and reach the fetus was established. The presence of EDCs, a majority of which are estrogen mimics, in the fetal environment during early development could potentially affect neurodevelopment, with implications for behavioural and neurological disorders in adult life. This review summarizes studies in animal models and human cohorts that aim to elucidate mechanisms of action of EDCs in the context of neurodevelopment and disease risk in adult life. This is a significant area of study as early brain development is heavily mediated by estrogen and could be particularly sensitive to EDC exposure. A network analysis presented using genes summarized in this review, further show a significant association with disorders such as major depressive disorder, alcoholic disorder, psychotic disorders and autism spectrum disorder. Functional outcomes such as alterations in memory, behaviour, cognition, learning memory, feeding behaviour and regulation of ion transport are also highlighted. Interactions between genes, receptors and signaling pathways like NMDA glutamate receptor activity, 5-hydroxytryptamine receptor activity, Ras-activated Ca₂⁺ influx and Grin2A interactions, provide further potential mechanisms of action of EDCs in mediating brain function. Taken together with the growing pool of human and animal studies, this review summarizes current status of EDC neurotoxicity research, limitations and future directions of study for researchers.

Effect of treadmill exercise on serum corticosterone, serum and hippocampal BDNF, hippocampal apoptosis and anxiety behavior in an ovariectomized rat model of post-traumatic stress disorder (PTSD)

There is a sex difference in vulnerability to PTSD and in response to therapeutic interventions. Since relation between gonadal hormones and PTSD has been revealed, this study aimed to understand the severity of PTSD-induced impairments after ovarian hormone deficiency and the influence of exercise on PTSD accompanied by ovarian hormone deficiency. Female adult Wistar rats were subjected to ovariectomy, PTSD, or combination ovariectomy plus PTSD. Twenty days after ovariectomy, PTSD was induced by single prolonged stress (SPS) model. The exercise started 14 days after SPS and continued for 4 weeks. Thirty minutes moderate treadmill exercise was planned for 5 days per week. On day 65, after assessing rats using the elevated plus-maze (EPM) test, corticosterone, BDNF, and apoptotic markers were tested. p < 0.05 was considered as significant level. The results showed that ovariectomy worsened the effect of SPS on hippocampal BDNF and led to greater increase in serum corticosterone and hippocampal caspase 3 and BAX in SPS rats. Also, ovariectomy exacerbated anxiety-like behavior in SPS rats. Exercise improved the alterations of hippocampal BDNF, corticosterone, caspase 3, and BAX in SPS ovariectomized rats. However, exercise had no statistically significant effect on anxiety-like behavior in this group. According to the results, exercise is effective to attenuate SPS-induced impairments in molecular and cellular responses even when the condition becomes more complicated due to ovarian hormone deficiency. However, exercise alone cannot help to improve behavior impairments in PTSD combined with an ovarian hormone deficiency. Therefore, exercise could likely be considered as a complementary intervention to strengthen other treatments.

Xenoestrogens impact brain estrogen receptor signaling during the female lifespan: A precursor to neurological disease?

Xenoestrogens, foreign synthetic chemicals mimicking estrogens, are lurking in our surroundings. Climate change may alter their toxicity and bioavailability. Since xenoestrogens have extremely high lipid solubility and are structurally similar to natural endogenous estrogens, they can bind to estrogen receptors (ERs) -alpha (ER-α) and -beta (ER-β). Scientific evidence accumulated over the past decades have suggested that natural 17β-estradiol (E2; a potent estrogen), via activation of its receptors, plays a pivotal role in regulation of brain development, differentiation, metabolism, synaptic plasticity, neuroprotection, cognition, anxiety, body temperature, feeding and sexual behavior. In the brain, ER-β is predominantly expressed in the various regions, including cerebral cortex and hippocampus, that have been shown to play a key role in cognition. Therefore, disturbances in function of ER-β mediated E2 signaling by xenoestrogens can lead to deleterious effects that potentiate a variety of neurological diseases starting from prenatal to post-menopause in women. The goal of this review is to identify the possible neurological effects of xenoestrogens that can alter estrogen receptor-mediated signaling in the brain during different stages of the female lifespan.

Age- and sex-specific effects of stress on parvalbumin interneurons in preclinical models: Relevance to sex differences in clinical neuropsychiatric and neurodevelopmental disorders

Stress is a major risk factor for neurodevelopmental and neuropsychiatric disorders, with the capacity to impact susceptibility to disease as well as long-term neurobiological and behavioral outcomes. Parvalbumin (PV) interneurons, the most prominent subtype of GABAergic interneurons in the cortex, are uniquely responsive to stress due to their protracted development throughout the highly plastic neonatal period and into puberty and adolescence. Additionally, PV + interneurons appear to respond to stress in a sex-specific manner. This review aims to discuss existing preclinical studies that support our overall hypothesis that the sex-and age-specific impacts of stress on PV + interneurons contribute to differences in individual vulnerability to stress across the lifespan, particularly in regard to sex differences in the diagnostic rate of neurodevelopmental and neuropsychiatric diseases in clinical populations. We also emphasize the importance of studying sex as a biological variable to fully understand the mechanistic and behavioral differences between males and females in models of neuropsychiatric disease.

Environmental Enrichment Mitigates Age-Related Metabolic Decline and Lewis Lung Carcinoma Growth in Aged Female Mice

Aging is a complex physiological process that leads to the progressive decline of metabolic and immune function, among other biological mechanisms. As global life expectancy increases, it is important to understand determinants of healthy aging-including environmental and genetic factors-and thus slow the onset or progression of age-related disease. Environmental enrichment (EE) is a housing environment wherein laboratory animals engage with complex physical and social stimulation. EE is a prime model to understand environmental influences on aging dynamics, as it confers an antiobesity and anticancer phenotype that has been implicated in healthy aging and health span extension. Although EE is frequently used to study malignancies in young mice, fewer studies characterize EE-cancer outcomes in older mice. Here, we used young (3-month-old) and aged (14-month-old) female C57BL/6 mice to determine whether EE would be able to mitigate age-related deficiencies in metabolic function and thus alter Lewis lung carcinoma (LLC) growth. Overall, EE improved metabolic function, resulting in reduced fat mass, increased lean mass, and improved glycemic processing; many of these effects were stronger in the aged cohort than in the young cohort, indicating an age-driven effect on metabolic responses. In the aged-EE cohort, subcutaneously implanted LLC tumor growth was inhibited and tumors exhibited alterations in various markers of apoptosis, proliferation, angiogenesis, inflammation, and malignancy. These results validate EE as an anticancer model in aged mice and underscore the importance of understanding environmental influences on cancer malignancy in aged populations. PREVENTION RELEVANCE: Environmental enrichment (EE) serves as a model of complex physical and social stimulation. This study validates EE as an anticancer intervention paradigm in aged mice and underscores the importance of understanding environmental influences on cancer malignancy in aged populations.

Orcinol glucoside improves the depressive-like behaviors of perimenopausal depression mice through modulating activity of hypothalamic-pituitary-adrenal/ovary axis and activating BDNF- TrkB-CREB signaling pathway

Orcinol Glucoside (OG), a phenolic glucoside isolated from C. orchioides, showed the antidepressant-like effect on chronic unpredictable mild stress (CUMS)-induced rats previously. This study was designed to determine whether OG could improve the depressive-like symptoms of perimenopausal depression (PMD) and the possible mechanisms involved. This research was performed on a PMD mice model established by a two-steps method of ovariectomy (OVX) followed CUMS. OG treatment effectively improved the depressive-like behaviors of OVX-CUMS mice, as indicated by increased sucrose intake in sucrose preference test (SPT), reduced immobility time in forced swimming test (FST), and tail suspension test (TST), lower frequency of grooming and defecation, increased actions of rearing, and prolonged duration in the center in open field test (OFT). OG treatment alleviated the OVX-CUMS induced dysfunction of hypothalamic-pituitary-ovarian (HPO) axis by increased serum estradiol (E2) and decreased ovarian hormones follicle stimulating hormone (FSH), luteinizing hormone (LH), and gonadotropin-releasing hormone (GnRH) in serum. Meanwhile, OG reversed the hyperactivity of hypothalamic-pituitary-adrenal (HPA) axis as evidenced by decreased CORT and ACTH in serum, reduced as well as the mRNA and protein expression of corticotropin-releasing hormone (CRH) in hypothalamus and hippocampus. Moreover, OG up-regulated the protein expression of BDNF, TrkB, and phosphorylation level of CREB and ERK1/2 in hippocampus. These findings demonstrated that OG improves depressive behaviors of OVX-CUMS mice by modulating of HPO/HPA axis dysfunction, and activating BDNF-TrkB-CREB signaling pathway.

Brain-derived neurotrophic factor (BDNF) affects the activity of the gonadotrophic axis in sheep

This study aimed to examine the hypothesis that BDNF modulates the activity of the gonadotrophic axis in sheep. Central infusions of BDNF were administered to sexually mature Polish Merino sheep. The sheep were randomly divided into three groups: the control group received intracerebroventricular (ICV) infusions of the vehicle, the BDNF 10 group received ICV infusions of BDNF at 10 μg/480 μL/day, and the BDNF 60 group was infused with BDNF at 60 μg/480 μL/day. A series of four infusions on three consecutive days was performed. Blood samples were collected on days 0 and 3 of the infusions. Immediately after the experiment, all the sheep were slaughtered, and selected structures of the hypothalamus and pituitaries were collected for Real Time RT-qPCR analysis. The collected plasma samples, as well as parts of pituitaries were stored for radioimmunoassay analysis of LH and FSH. Central treatment with exogenous BDNF stimulated GnRH mRNA expression in the preoptic area, as well as GnRH-R mRNA in the pituitary. Furthermore, substantial changes in the KNDy mRNA expression in the mediobasal hypothalamus were observed after the ICV BDNF administration. Additionally, central BDNF infusion caused a decrease in LH concentration and a simultaneous increase in FSH concentration in peripheral blood. Neither pulse amplitude nor pulse frequency for any gonadotrophin was affected in both groups of sheep that received BDNF infusion. Our results revealed that exogenous BDNF affects GnRH and KNDy gene expression and changes in the LH and FSH pituitary cell secretory activities. These findings suggest that BDNF may participate in the mechanism modulating the activity of the gonadotrophic axis at the central level in female sheep.

Selective ER-β agonists alleviate neuronal deficits in insulin-resistant estrogen-deficient rats

OBJECTIVE

The present study aimed to determine the effect of estrogen receptor (ER) agonists on depression and memory impairment in insulin-resistant ovariectomized (OVX) rats.

METHODS

Rats underwent bilateral ovariectomy, and low-dose streptozotocin (STZ) and a high-fat diet (58% fat, 25% protein, and 17% carbohydrates as a percentage of kilocalories) were administered to induce an estrogen-deficient insulin-resistant state. After 1 week of STZ administration, rats were treated with 17β-estradiol (17βE2) and selective ER-α (propylpyrazoletriol) and ER-β (diarylpropionitrile) agonists (10 μg/kg subcutaneously). Memory was evaluated using the Morris water maze and depression using the forced swim test.

RESULTS

Treatment with selective ER-β agonist and 17βE2 but not with selective ER-α agonist significantly modulated the neurobehavioral deficits in insulin-resistant OVX rats. These neurobehavioral parameters were further correlated with brain-derived neurotrophic factor (BDNF) levels and acetylcholinesterase (AChE) activity. Selective ER-β agonist and 17βE2 significantly modulated BDNF levels and AChE activity in insulin-resistant OVX rats. Significant increases in estradiol and uterine weight were observed in 17βE2-treated rats, but selective ER agonists did not show any effect.

CONCLUSION

ER-β agonist can be an effective strategy for the mitigation of memory loss and depression in an estrogen-deficient insulin-resistant state without all of the deleterious feminizing effects that occur with the use of 17βE2.

The Impact of Estrogen and Estrogen-Like Molecules in Neurogenesis and Neurodegeneration: Beneficial or Harmful?

Estrogens and estrogen-like molecules can modify the biology of several cell types. Estrogen receptors alpha (ERα) and beta (ERβ) belong to the so-called classical family of estrogen receptors, while the G protein-coupled estrogen receptor 1 (GPER-1) represents a non-classical estrogen receptor mainly located in the plasma membrane. As estrogen receptors are ubiquitously distributed, they can modulate cell proliferation, differentiation, and survival in several tissues and organs, including the central nervous system (CNS). Estrogens can exert neuroprotective roles by acting as anti-oxidants, promoting DNA repair, inducing the expression of growth factors, and modulating cerebral blood flow. Additionally, estrogen-dependent signaling pathways are involved in regulating the balance between proliferation and differentiation of neural stem/progenitor cells (NSPCs), thus influencing neurogenic processes. Since several estrogen-based therapies are used nowadays and estrogen-like molecules, including phytoestrogens and xenoestrogens, are omnipresent in our environment, estrogen-dependent changes in cell biology and tissue homeostasis have gained attention in human health and disease. This article provides a comprehensive literature review on the current knowledge of estrogen and estrogen-like molecules and their impact on cell survival and neurodegeneration, as well as their role in NSPCs proliferation/differentiation balance and neurogenesis.

17β-estradiol activation of dorsal hippocampal TrkB is independent of increased mature BDNF expression and is required for enhanced memory consolidation in female mice

The potent estrogen 17β-estradiol (E₂) is known to enhance hippocampal memory and plasticity, however the molecular mechanisms underlying these effects remain unclear. Brain derived neurotrophic factor (BDNF) and its receptor tropomyosin receptor kinase B (TrkB) are regulated by E₂, but the potential mechanistic roles of neurotrophic signaling in E₂-induced enhancement of memory are not well understood. Here, we examined the effects of hippocampal TrkB signaling on E₂-induced enhancement of memory consolidation in the object placement and recognition tasks. Bilateral infusion of the TrkB antagonist ANA-12 into the dorsal hippocampus of ovariectomized female mice blocked E₂-induced enhancement of memory consolidation, supporting a role for TrkB-mediated signaling in estrogenic regulation of memory. Although dorsal hippocampal E₂ infusion increased levels of phospho-TrkB and mature BDNF (mBDNF) in the dorsal hippocampus within 4-6 h, E₂-induced increases in hippocampal mBDNF expression were not required for hippocampal TrkB activation and were not inhibited by TrkB antagonism. Thus, E₂ regulates TrkB signaling to facilitate memory consolidation in a manner independent of mBDNF expression. Together these results provide the first direct evidence that E₂ modulation of hippocampal TrkB signaling is required for its beneficial effects on memory consolidation and provide additional characterization of the ways in which TrkB/BDNF signaling is regulated by E₂ in the hippocampus.

Akkouh I, Hughes T, Frei E, A. Andreassen O, Djurovic S. Using iPSC Models to Understand the Role of Estrogen in Neuron-Glia Interactions in Schizophrenia and Bipolar Disorder

Schizophrenia (SCZ) and bipolar disorder (BIP) are severe mental disorders with a considerable disease burden worldwide due to early age of onset, chronicity, and lack of efficient treatments or prevention strategies. Whilst our current knowledge is that SCZ and BIP are highly heritable and share common pathophysiological mechanisms associated with cellular signaling, neurotransmission, energy metabolism, and neuroinflammation, the development of novel therapies has been hampered by the unavailability of appropriate models to identify novel targetable pathomechanisms. Recent data suggest that neuron-glia interactions are disturbed in SCZ and BIP, and are modulated by estrogen (E2). However, most of the knowledge we have so far on the neuromodulatory effects of E2 came from studies on animal models and human cell lines, and may not accurately reflect many processes occurring exclusively in the human brain. Thus, here we highlight the advantages of using induced pluripotent stem cell (iPSC) models to revisit studies of mechanisms underlying beneficial effects of E2 in human brain cells. A better understanding of these mechanisms opens the opportunity to identify putative targets of novel therapeutic agents for SCZ and BIP. In this review, we first summarize the literature on the molecular mechanisms involved in SCZ and BIP pathology and the beneficial effects of E2 on neuron-glia interactions. Then, we briefly present the most recent developments in the iPSC field, emphasizing the potential of using patient-derived iPSCs as more relevant models to study the effects of E2 on neuron-glia interactions.

Brain-Derived Neurotrophic Factor Regulates Ishikawa Cell Proliferation through the TrkB-ERK1/2 Signaling Pathway

(1) Background: Endometrial regulation is a necessary condition for maintaining normal uterine physiology, which is driven by many growth factors. Growth factors produced in the endometrium are thought to be related to the proliferation of endometrial cells induced by estradiol-17β (E₂). In this study, we found that E₂ can induce the secretion of brain-derived neurotrophic factor (BDNF) in Ishikawa cells (the cells of an endometrial cell line). Furthermore, Ishikawa cells were used in exploring the regulatory role of BDNF in endometrial cells and to clarify the potential mechanism. (2) Methods: Ishikawa cells were treated with different concentrations of BDNF (100, 200, 300, 400, and 500 ng/mL). The mRNA expression levels of various proliferation-related genes were detected through quantitative reverse transcription polymerase chain reaction, and the expression of various proliferation-related genes was detected by knocking out BDNF or inhibiting the binding of BDNF to its receptor TrkB. The expression levels of various proliferation-related genes were detected by performing Western blotting on the TrkB-ERK1/2 signaling pathway. (3) Results: Exogenous BDNF promoted the growth of the Ishikawa cells, but the knocking down of BDNF or the inhibition of TrkB reduced their growth. Meanwhile, BDNF enhanced cell viability and increased the expression of proliferation-related genes, including cyclin D1 and cyclin E2. More importantly, the BDNF-induced proliferation of the Ishikawa cells involved the ERK1/2 signaling pathway. (4) Conclusions: The stimulating effect of exogenous E₂ on the expression of BDNF in the uterus and the action of BDNF promoted the proliferation of the Ishikawa cells through the TrkB-ERK1/2 signal pathway.

Brain-derived neurotrophic factor (BDNF) expression and function in the mammalian reproductive Tract

BACKGROUND

Neurotrophins of the nerve growth factor family are soluble polypeptides that are best known for their role in nerve growth, survival and differentiation in the central nervous system. A growing body of literature shows that neurotrophins and their receptors are also expressed throughout the reproductive tract.

OBJECTIVE AND RATIONALE

Neurotrophins are key regulatory proteins in reproductive physiology during development and throughout adult life. Of the neurotrophins, the literature describing the expression and function of brain-derived neurotrophic factor (BDNF) and its high-affinity receptor, neurotrophin receptor kinase-2 (NTRK2), has been expanding rapidly. We therefore conducted a systematic inductive qualitative review of the literature to better define the role of the BDNF in the reproductive tract. We postulate that BDNF and NTRK2 are central regulatory proteins throughout the reproductive system.

SEARCH METHODS

An electronic search of Medline (PubMed) and Web of Science for articles relating to BDNF and the reproductive system was carried out between January 2018 and February 2019.

OUTCOMES

In the ovary, BDNF expression and levels have been linked with follicle organisation during ovarian development, follicle recruitment and growth and oocyte maturation. In the endometrium, BDNF is involved in cell proliferation and neurogenesis. In contrast, literature describing the role of BDNF in other reproductive tissues is sparse and BDNF-NTRK2 signalling in the male reproductive tract has been largely overlooked. Whilst estradiol appears to be the primary regulator of BDNF expression, we also identified reports describing binding sites for glucocorticoid and myocyte enhancer factor-2, a calcium-response element through activation of an N-methyl-D-aspartate (NMDA) receptor, and aryl hydrocarbon receptor nuclear transporter protein-4 (ARNT) response elements in promoter regions of the BDNF gene. Expression is also regulated by multiple microRNAs and post-translational processing of precursor proteins and intracellular shuttling. BDNF-NTRK2 signalling is modulated through tissue specific receptor expression of either the full-length or truncated NTRK2 receptor; however, the functional importance remains to be elucidated. Dysregulation of BDNF expression and circulating concentrations have been implicated in several reproductive disorders including premature ovarian failure, endometriosis, pre-eclampsia, intra-uterine growth restriction (IUGR) and several reproductive cancers.

WIDER IMPLICATIONS

We conclude that BDNF and its receptors are key regulatory proteins central to gonadal development, ovarian regulation and uterine physiology, as well as embryo and placenta development. Furthermore, dysregulation of BDNF-NTRK2 in reproductive diseases suggests their potential role as candidate clinical markers of disease and potential therapeutic targets.

Dose-dependent effects of testosterone on spatial learning strategies and brain-derived neurotrophic factor in male rats

Studies suggest that males outperform females on some spatial tasks. This may be due to the effects of sex steroids on spatial strategy preferences. Past experiments with male rats have demonstrated that low doses of testosterone bias them toward a response strategy, whereas high doses of testosterone bias them toward a place strategy. We investigated the effect of different testosterone doses on the ability of male rats to effectively employ these two spatial learning strategies. Furthermore, we quantified concentrations of brain-derived neurotrophic factor (pro-, mature-, and total BDNF) in the prefrontal cortex, hippocampus, and striatum. All rats were bilaterally castrated and assigned to one of three daily injection doses of testosterone propionate (0.125, 0.250, or 0.500 mg/rat) or a control injection of the drug vehicle. Using a plus-maze protocol, we found that a lower testosterone dose (0.125 mg) significantly improved rats' performance on a response task, whereas a higher testosterone dose (0.500 mg) significantly improved rats' performance on a place task. In addition, we found that a low dose of testosterone (0.125 mg) increased total BDNF in the striatum, while a high dose (0.500 mg) increased total BDNF in the hippocampus. Taken altogether, these results suggest that high and low levels of testosterone enhance performance on place and response spatial tasks, respectively, and this effect is associated with changes in BDNF levels within relevant brain regions.

The Influence of the BDNF Val66Met Polymorphism on the Association of Regular Physical Activity With Cognition Among Individuals With Diabetes

INTRODUCTION

Diabetes is associated with cognitive dysfunction that comes with substantial lifetime consequences, such as interference with diabetes self-management and reduced quality of life. Although regular physical activity has been consistently shown to enhance cognitive function among healthy subjects, significant interpersonal differences in exercise-induced cognitive outcomes have been reported among brain-derived neurotrophic factor (BDNF) Val/Val vs. Met carriers. However, the evidence on how the BDNF Val66Met variant influences the relationship between regular physical activity and cognition among individuals with diabetes is currently lacking.

METHODS

A total of 3,040 individuals with diabetes were included in this analysis using data from the Health and Retirement Study. Associations among moderate and vigorous physical activities (MVPA) and measures of cognitive function were evaluated using multivariable linear regression models within each stratum of the Val66Met genotypes.

RESULTS

MVPA was more strongly associated with total cognitive score, mental status, and words recall among Met/Met carriers, compared to Val/Val and Val/Met carriers.

CONCLUSIONS

This study provided preliminary findings on how BDNF variants may modulate the exercise-induced cognitive benefits among mid-aged and older adults with diabetes. Given the limitations of the current study, it is necessary for randomized controlled trials to stratify by BDNF genotypes to more conclusively determine whether Met carriers benefit more from increased physical activity. In addition, future research is needed to examine how the interplay of BDNF Val66Met variants, DNA methylation, and physical activity may have an impact on cognitive function among adults with diabetes.

Sex Differences in the Epilepsies and Associated Comorbidities: Implications for Use and Development of Pharmacotherapies

The epilepsies are common neurologic disorders characterized by spontaneous recurrent seizures. Boys, girls, men, and women of all ages are affected by epilepsy and, in many cases, by associated comorbidities as well. The primary courses of treatment are pharmacological, dietary, and/or surgical, depending on several factors, including the areas of the brain affected and the severity of the epilepsy. There is a growing appreciation that sex differences in underlying brain function and in the neurobiology of epilepsy are important factors that should be accounted for in the design and development of new therapies. In this review, we discuss the current knowledge on sex differences in epilepsy and associated comorbidities, with emphasis on those aspects most informative for the development of new pharmacotherapies. Particular focus is placed on sex differences in the prevalence and presentation of various focal and generalized epilepsies; psychiatric, cognitive, and physiologic comorbidities; catamenial epilepsy in women; sex differences in brain development; the neural actions of sex and stress hormones and their metabolites; and cellular mechanisms, including brain-derived neurotrophic factor signaling and neuronal-glial interactions. Further attention placed on potential sex differences in epilepsies, comorbidities, and drug effects will enhance therapeutic options and efficacy for all patients with epilepsy. SIGNIFICANCE STATEMENT: Epilepsy is a common neurological disorder that often presents together with various comorbidities. The features of epilepsy and seizure activity as well as comorbid afflictions can vary between men and women. In this review, we discuss sex differences in types of epilepsies, associated comorbidities, pathophysiological mechanisms, and antiepileptic drug efficacy in both clinical patient populations and preclinical animal models.

The Epistasis Project: A Multi-Cohort Study of the Effects of BDNF, DBH, and SORT1 Epistasis on Alzheimer's Disease Risk

Pre-synaptic secretion of brain-derived neurotrophic factor (BDNF) from noradrenergic neurons may protect the Alzheimer's disease (AD) brain from amyloid pathology. While the BDNF polymorphism (rs6265) is associated with faster cognitive decline and increased hippocampal atrophy, a replicable genetic association of BDNF with AD risk has yet to be demonstrated. This could be due to masking by underlying epistatic interactions between BDNF and other loci that encode proteins involved in moderating BDNF secretion (DBH and Sortilin). We performed a multi-cohort case-control association study of the BDNF, DBH, and SORT1 loci comprising 5,682 controls and 2,454 AD patients from Northern Europe (87% of samples) and Spain (13%). The BDNF locus was associated with increased AD risk (odds ratios; OR = 1.1-1.2, p = 0.005-0.3), an effect size that was consistent in the Northern European (OR = 1.1-1.2, p = 0.002-0.8) but not the smaller Spanish (OR = 0.8-1.6, p = 0.4-1.0) subset. A synergistic interaction between BDNF and sex (synergy factor; SF = 1.3-1.5 p = 0.002-0.02) translated to a greater risk of AD associated with BDNF in women (OR = 1.2-1.3, p = 0.007-0.00008) than men (OR = 0.9-1.0, p = 0.3-0.6). While the DBH polymorphism (rs1611115) was also associated with increased AD risk (OR = 1.1, p = 0.04) the synergistic interaction (SF = 2.2, p = 0.007) between BDNF (rs6265) and DBH (rs1611115) contributed greater AD risk than either gene alone, an effect that was greater in women (SF = 2.4, p = 0.04) than men (SF = 2.0, p = 0.2). These data support a complex genetic interaction at loci encoding proteins implicated in the DBH-BDNF inflammatory pathway that modifies AD risk, particularly in women.

The Impact of Estradiol on Neurogenesis and Cognitive Functions in Alzheimer's Disease

Alzheimer's disease (AD) is described as cognitive and memory impairments with a sex-related epidemiological profile, affecting two times more women than men. There is emerging evidence that alternations in the hippocampal neurogenesis occur at the early stage of AD. Therapies that may effectively slow, stop, or regenerate the dying neurons in AD are being extensively investigated in the last few decades, but none has yet been found to be effective. The regulation of endogenous neurogenesis is one of the main therapeutic targets for AD. Mounting evidence indicates that the neurosteroid estradiol (17β-estradiol) plays a supporting role in neurogenesis, neuronal activity, and synaptic plasticity of AD. This effect may provide preventive and/or therapeutic approaches for AD. In this article, we discuss the molecular mechanism of potential estradiol modulatory action on endogenous neurogenesis, synaptic plasticity, and cognitive function in AD.

Brain-derived Neurotrophic Factor and TrkB Levels in Mice that Lack Vesicular Zinc: Effects of Age and Sex

In certain neurons, zinc ions are stored in synaptic vesicles by zinc transporter 3 (ZnT3). Vesicular zinc can then be released synaptically to modulate myriad targets. In vitro evidence indicates that these targets may include brain-derived neurotrophic factor (BDNF) and its receptor, tropomyosin receptor kinase B (TrkB). But the effects of vesicular zinc on BDNF and TrkB in the intact brain are unclear. Studies of mice that lack ZnT3 - and, as a result, vesicular zinc - have shown abnormalities in BDNF and TrkB levels, but results have been mixed and are therefore difficult to interpret. This might be caused by differences in the age or sex of mice tested. In the present study, we measured BDNF and TrkB levels in the hippocampus and neocortex, comparing wild type and ZnT3 knockout mice of both sexes at two ages (5 and 12 weeks). We also examined BDNF mRNA expression and protein levels at an intermediate age (8-10 weeks). We found that, regardless of age or sex, BDNF and TrkB protein levels did not differ between wild type and ZnT3 knockout mice. There were sex-specific differences in BDNF protein and mRNA expression, however. BDNF protein levels increased with age in female mice but not in males. And in females, but not males, ZnT3 KO mice exhibited great hippocampal BDNF mRNA expression than wild type mice. We conclude that, at least in naïve mice housed under standard laboratory conditions, elimination of vesicular zinc does not affect BDNF or TrkB protein levels.

Hypothalamic C2-domain protein involved in MC4R trafficking and control of energy balance

OBJECTIVE

Rates of overweight and obesity epidemic have risen significantly in the past few decades, and 34% of adults and 15-20% of children and adolescents in the United States are now obese. Melanocortin receptor 4 (MC4R), contributes to appetite control in hypothalamic neurons and is a target for future anti-obesity treatments (such as setmelanotide) or novel drug development effort. Proper MC4R trafficking regulation in hypothalamic neurons is crucial for normal neural control of homeostasis and is altered in obesity and in presence of lipids. The mechanisms underlying altered MC4R trafficking in the context of obesity is still unclear. Here, we discovered that C2CD5 expressed in the hypothalamus is involved in the regulation of MC4R endocytosis. This study unmasked a novel trafficking protein nutritionally regulated in the hypothalamus providing a novel target for MC4R dependent pathways involved in bodyweight homeostasis and Obesity.

METHODS

To evaluate the expression of C2cd5, we first used in situ hybridization and RNAscope technology in combination with electronic microscopy. For in vivo, we characterized the energy balance of wild type (WT) and C2CD5 whole-body knockout (C2CD5KO) mice fed normal chow (NC) and/or western-diet (high-fat/high-sucrose/cholesterol) (WD). To this end, we performed comprehensive longitudinal assessment of bodyweight, energy balance (food intake, energy expenditure, locomotor activity using TSE metabolic cages), and glucose homeostasis. In addition, we evaluated the consequence of loss of C2CD5 on feeding behavior changes normally induced by MC4R agonist (Melanotan, MTII) injection in the paraventricular hypothalamus (PVH). For in vitro approach, we tease out the role of C2CD5 and its calcium sensing domain C2 in MC4R trafficking. We focused on endocytosis of MC4R using an antibody feeding experiment (in a neuronal cell line - Neuro2A (N2A) stably expressing HA-MC4R-GFP; against HA-tag and analyzed by flux cytometry).

RESULTS

We found that 1) the expression of hypothalamic C2CD5 is decreased in diet-induced obesity models compared to controls, 2) mice lacking C2CD5 exhibit an increase in food intake compared to WT mice, 3) C2CD5 interacts with endocytosis machinery in hypothalamus, 4) loss of functional C2CD5 (lacking C2 domain) blunts MC4R endocytosis in vitro and increases MC4R at the surface that fails to respond to MC4R ligand, and, 5) C2CD5KO mice exhibit decreased acute responses to MTII injection into the PVH.

CONCLUSIONS

Based on these, we conclude that hypothalamic C2CD5 is involved in MC4R endocytosis and regulate bodyweight homeostasis. These studies suggest that C2CD5 represents a new protein regulated by metabolic cues and involved in metabolic receptor endocytosis. C2CD5 represent a new target and pathway that could be targeted in Obesity.

Towards a comprehensive etiopathogenetic and pathophysiological theory of multiple sclerosis

Background: Multiple sclerosis (MS) is a neurodegenerative disease caused by dysfunction of the immune system that affects the central nervous system (CNS). It is characterized by demyelination, chronic inflammation, neuronal and oligodendrocyte loss and reactive astrogliosis. It can result in physical disability and acute neurological and cognitive problems. Despite the gains in knowledge of immunology, cell biology, and genetics in the last five decades, the ultimate etiology or specific elements that trigger MS remain unknown. The objective of this review is to propose a theoretical basis for MS etiopathogenesis.Methods: Search was done by accessing PubMed/Medline, EBSCO, and PsycINFO databases. The search string used was "(multiple sclerosis* OR EAE) AND (pathophysiology* OR etiopathogenesis)". The electronic databases were searched for titles or abstracts containing these terms in all published articles between January 1, 1960, and June 30, 2019. The search was filtered down to 362 articles which were included in this review.Results: A framework to better understand the etiopathogenesis and pathophysiology of MS can be derived from four essential factors; mitochondria dysfunction (MtD) & oxidative stress (OS), vitamin D (VD), sex hormones and thyroid hormones. These factors play a direct role in MS etiopathogenesis and have a modulatory effect on many other factors involved in the disease.Conclusions: For better MS prevention and treatment outcomes, efforts should be geared towards treating thyroid problems, sex hormone alterations, VD deficiency, sleep problems and melatonin alterations. MS patients should be encouraged to engage in activities that boost total antioxidant capacity (TAC) including diet and regular exercise and discouraged from activities that promote OS including smoking and alcohol consumption.