Antidepressant activity of ω-3 polyunsaturated fatty acids in ovariectomized rats: role of neuroinflammation and microglial polarization

Ameliorative effect of α-tocopherol and tocotrienol-rich palm oil extract on menopause-associated mood disorder in ovariectomized mice

Menopause-associated mood disorder is characterized by emotional depression, anxiety, and stress, which accompany hypogonadism in women in the menopausal phase. The current treatment for menopause-associated mood disorder provides only symptomatic relief and is associated with many side effects. Supplementation with vitamin E has been shown to be effective in ameliorating anxiety and depression. However, the effects of vitamin E and its underlying mechanism in ameliorating menopause-associated mood disorders remain uncertain. This work evaluated the effects of α-tocopherol and tocotrienol-rich palm oil extract on depressive and anxiety-related phenotypes induced by estrogen deficiency through ovariectomy in mice. Our study revealed that ovariectomized mice exhibited alterations in behavior indicative of depressive- and anxiety-like behaviors. The serum corticosterone level, a glucocorticoid hormone associated with stress, was found to be elevated in ovariectomized mice as compared to the sham group. Oral administration of α-tocopherol (50 and 100 mg/kg) and tocotrienol-rich palm oil extract (100 and 200 mg/kg) for 14 days alleviated these behavioral changes, as observed in open field, social interaction, and tail suspension tests. However, treatment with tocotrienol-rich palm oil extract, but not α-tocopherol, modulated the depressive- and anxiety-like responses in ovariectomized mice subjected to chronic restraint stress. Both treatments suppressed the elevated serum corticosterone level. Our findings suggested that α-tocopherol and tocotrienol-rich palm oil extract alleviated menopause-associated mood disorder, at least in part, by modulating the hypothalamic-pituitary-adrenal (HPA) axis. The findings of this study can provide a new foundation for the treatment of menopause-associated depressive- and anxiety-like phenotypes, for the betterment of psychological wellbeing.

The intersection between menopause and depression: overview of research using animal models

Menopausal women may experience symptoms of depression, sometimes even progressing clinical depression requiring treatment to improve quality of life. While varying levels of estrogen in perimenopause may contribute to an increased biological vulnerability to mood disturbances, the effectiveness of estrogen replacement therapy (ERT) in the relief of depressive symptoms remains controversial. Menopausal depression has a complex, multifactorial etiology, that has limited the identification of optimal treatment strategies for the management of this psychiatric complaint. Nevertheless, clinical evidence increasingly supports the notion that estrogen exerts neuroprotective effects on brain structures related to mood regulation. Indeed, research using preclinical animal models continues to improve our understanding of menopause and the effectiveness of ERT and other substances at treating depression-like behaviors. However, questions regarding the efficacy of ERT in perimenopause have been raised. These questions may be answered by further investigation using specific animal models of reduced ovarian function. This review compares and discusses the advantages and pitfalls of different models emulating the menopausal stages and their relationship with the onset of depressive-like signs, as well as the efficacy and mechanisms of conventional and novel ERTs in treating depressive-like behavior. Ovariectomized young rats, middle-to-old aged intact rats, and females treated with reprotoxics have all been used as models of menopause, with stages ranging from surgical menopause to perimenopause. Additionally, this manuscript discusses the impact of organistic and therapeutic variables that may improve or reduce the antidepressant response of females to ERT. Findings from these models have revealed the complexity of the dynamic changes occurring in brain function during menopausal transition, reinforcing the idea that the best approach is timely intervention considering the opportunity window, in addition to the careful selection of treatment according to the presence or absence of reproductive tissue. Additionally, data from animal models has yielded evidence to support new promising estrogens that could be considered as ERTs with antidepressant properties and actions in endocrine situations in which traditional ERTs are not effective.

Estrogen-immuno-neuromodulation disorders in menopausal depression

A significant decrease in estrogen levels puts menopausal women at high risk for major depression, which remains difficult to cure despite its relatively clear etiology. With the discovery of abnormally elevated inflammation in menopausal depressed women, immune imbalance has become a novel focus in the study of menopausal depression. In this paper, we examined the characteristics and possible mechanisms of immune imbalance caused by decreased estrogen levels during menopause and found that estrogen deficiency disrupted immune homeostasis, especially the levels of inflammatory cytokines through the ERα/ERβ/GPER-associated NLRP3/NF-κB signaling pathways. We also analyzed the destruction of the blood-brain barrier, dysfunction of neurotransmitters, blockade of BDNF synthesis, and attenuation of neuroplasticity caused by inflammatory cytokine activity, and investigated estrogen-immuno-neuromodulation disorders in menopausal depression. Current research suggests that drugs targeting inflammatory cytokines and NLRP3/NF-κB signaling molecules are promising for restoring homeostasis of the estrogen-immuno-neuromodulation system and may play a positive role in the intervention and treatment of menopausal depression.

Role of estrogen in treatment of female depression

Depression is a neurological disorder that profoundly affects human physical and mental health, resulting in various changes in the central nervous system. Despite several prominent hypotheses, such as the monoaminergic theory, hypothalamic-pituitary-adrenal (HPA) axis theory, neuroinflammation, and neuroplasticity, the current understanding of depression's pathogenesis remains incomplete. Importantly, depression is a gender-dimorphic disorder, with women exhibiting higher incidence rates than men. Given estrogen's pivotal role in the menstrual cycle, it is reasonable to postulate that its fluctuating levels could contribute to the pathogenesis of depression. Estrogen acts by binding to a diversity of receptors, which are widely distributed in the central nervous system. An abundance of research has established that estrogen and its receptors play a crucial role in depression, spanning pathogenesis and treatment. In this comprehensive review, we provide an in-depth analysis of the fundamental role of estrogen and its receptors in depression, with a focus on neuroinflammation, neuroendocrinology, and neuroplasticity. Furthermore, we discuss potential mechanisms underlying the therapeutic effects of estrogen in the treatment of depression, which may pave the way for new antidepressant drug development and alternative treatment options.

Suanzaoren decoction improves depressive-like behaviors by regulating the microbiota-gut-brain axis via inhibiting TLR4/NFκB/NLRP3 inflammation signal pathway

Depression is a common but serious sickness which causes a considerable burden on individuals and society. Recently, it has been well established that the occurrence of depression was related to the microbiota-gut-brain axis. The toll-like receptor 4 (TLR4)/ nuclear factor kappa-B kinase (NFκB)/ NOD-like receptor thermal protein domain associated protein 3 (NLRP3) pathway is closely associated with the regulation of microbiota-gut-brain axis. Suanzaoren Decoction (SZRD), which recorded in Jin Gui Yao Lve in Han dynasty, has been used for treating insomnia and depression for a long time. However, the action mechanism of the depression regulation through the TLR4/NFκB/NLRP3 pathway by SZRD was still unclear. In this study, SZRD was firstly performed on a chronic unpredictable mild stress (CUMS) mice model. The results of behavioral tests showed that SZRD treatment could ameliorate the depressive-like behaviors of CUMS mice effectively. According to our previous researches about the components of SZRD in vitro and in vivo, the identification of serum metabolites in depression model rats was further analyzed qualitatively using ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry. 27 prototypes and 44 metabolites were identified. The main types of metabolic reactions are glucuronization, sulfation, and so on. Then, using immunohistochemistry and western blotting to monitor the difference in activation of TLR4/NFκB/NLRP3 signaling pathway in mice brain and colon. The results showed that SZRD treatment could reduce expression levels of related factors. Additionally, the SZRD treatment could also inhibit the histopathological damage in the path morphology of the hippocampus and colon. The results of 16SrRNA demonstrated that SZRD could reduce the dysbiosis of the intestinal flora of depressive mice. The above results provided important information for studying the action mechanism of SZRD in treating depression by regulating microbiota-gut-brain axis via inhibiting TLR4/NFκB/NLRP3 pathway.

A small-molecule TLR4 antagonist reduced neuroinflammation in female E4FAD mice

BACKGROUND

APOE genotype is the greatest genetic risk factor for sporadic Alzheimer's disease (AD). APOE4 increases AD risk up to 12-fold compared to APOE3, an effect that is greater in females. Evidence suggests that one-way APOE could modulate AD risk and progression through neuroinflammation. Indeed, APOE4 is associated with higher glial activation and cytokine levels in AD patients and mice. Therefore, identifying pathways that contribute to APOE4-associated neuroinflammation is an important approach for understanding and treating AD. Human and in vivo evidence suggests that TLR4, one of the key receptors involved in the innate immune system, could be involved in APOE-modulated neuroinflammation. Consistent with that idea, we previously demonstrated that the TLR4 antagonist IAXO-101 can reduce LPS- and Aβ-induced cytokine secretion in APOE4 glial cultures. Therefore, the goal of this study was to advance these findings and determine whether IAXO-101 can modulate neuroinflammation, Aβ pathology, and behavior in mice that express APOE4.

METHODS

We used mice that express five familial AD mutations and human APOE3 (E3FAD) or APOE4 (E4FAD). Female and male E4FAD mice and female E3FAD mice were treated with vehicle or IAXO-101 in two treatment paradigms: prevention from 4 to 6 months of age or reversal from 6 to 7 months of age. Learning and memory were assessed by modified Morris water maze. Aβ deposition, fibrillar amyloid deposition, astrogliosis, and microgliosis were assessed by immunohistochemistry. Soluble levels of Aβ and apoE, insoluble levels of apoE and Aβ, and IL-1β were measured by ELISA.

RESULTS

IAXO-101 treatment resulted in lower Iba-1 coverage, lower number of reactive microglia, and improved memory in female E4FAD mice in both prevention and reversal paradigms. IAXO-101-treated male E4FAD mice also had lower Iba-1 coverage and reactivity in the RVS paradigm, but there was no effect on behavior. There was also no effect of IAXO-101 treatment on neuroinflammation and behavior in female E3FAD mice.

CONCLUSION

Our data supports that TLR4 is a potential mechanistic therapeutic target for modulating neuroinflammation and cognition in APOE4 females.

Roles of microglia in adult hippocampal neurogenesis in depression and their therapeutics

Adult hippocampal neurogenesis generates functional neurons from neural progenitor cells in the hippocampal dentate gyrus (DG) to complement and repair neurons and neural circuits, thus benefiting the treatment of depression. Increasing evidence has shown that aberrant microglial activity can disrupt the appropriate formation and development of functional properties of neurogenesis, which will play a crucial role in the occurrence and development of depression. However, the mechanisms of the crosstalk between microglia and adult hippocampal neurogenesis in depression are not yet fully understood. Therefore, in this review, we first introduce recent discoveries regarding the roles of microglia and adult hippocampal neurogenesis in the etiology of depression. Then, we systematically discuss the possible mechanisms of how microglia regulate adult hippocampal neurogenesis in depression according to recent studies, which involve toll-like receptors, microglial polarization, fractalkine-C-X3-C motif chemokine receptor 1, hypothalamic-pituitary-adrenal axis, cytokines, brain-derived neurotrophic factor, and the microbiota-gut-brain axis, etc. In addition, we summarize the promising drugs that could improve the adult hippocampal neurogenesis by regulating the microglia. These findings will help us understand the complicated pathological mechanisms of depression and shed light on the development of new treatment strategies for this disease.

Antidepressant-like Effects of Representative Types of Food and Their Possible Mechanisms

Depression is a mental disorder characterized by low mood, lack of motivation, negative cognitive outlook, and sleep problems. Suicide may occur in severe cases, although suicidal thoughts are not seen in all cases. Globally, an estimated 350 million individuals grapple with depression, as reported by the World Health Organization. At present, drug and psychological treatments are the main treatments, but they produce insufficient responses in many patients and fail to work at all in many others. Consequently, treating depression has long been an important topic in society. Given the escalating prevalence of depression, a comprehensive strategy for managing its symptoms and impacts has garnered significant attention. In this context, nutritional psychiatry emerges as a promising avenue. Extensive research has underscored the potential benefits of a well-rounded diet rich in fruits, vegetables, fish, and meat in alleviating depressive symptoms. However, the intricate mechanisms linking dietary interventions to brain function alterations remain largely unexplored. This review delves into the intricate relationship between dietary patterns and depression, while exploring the plausible mechanisms underlying the impact of dietary interventions on depression management. As we endeavor to unveil the pathways through which nutrition influences mental well-being, a holistic perspective that encompasses multidisciplinary strategies gains prominence, potentially reshaping how we approach and address depression.

Anti-apoptotic effect of menaquinone-7 protects the brain of ovariectomized rats

Background

Mood and memory deterioration occurs after ovariectomy (OVX) with various degrees and sometimes requires medical intervention. Menaquinone-7 (MK-7) is a potent isoform of vitamin K2 and has many effects on the bone and cardiovascular system. However, the effect of MK-7 on the brain and its mechanisms of action are still unclear. This study was performed to investigate the effect of MK-7 on mood and memory disorders following ovariectomy. Thirty-two female albino rats were divided into four groups (n = 8). Group I (control group) included sham-operated rats with sunflower oil intake. Group II (K2) included sham-operated rats with an intake of MK-7 dissolved in sunflower oil. Group III (K2 OVX) included ovariectomized rats with an intake of MK-7 dissolved in sunflower oil. Group IV(OVX) included ovariectomized rats with sunflower oil intake. Working memory, anxiety, depression, and sociability behaviors were investigated in all groups. Gene expression of BAX, BCL2, and p53 was measured in the hippocampus of all groups by real-time PCR. Besides, BAX/BCL2 ratio was calculated.

Results

Working memory, anxiety, depression, and sociability behaviors in the OVX rats showed a significant change compared to the sham-operated. However, the intake of MK-7 after the OVX resulted in significant improvement. Regarding hydrogen peroxide and MDA activity, they were significantly higher in the OVX group compared to the sham-operated groups, while in the K2OVX group, their activity showed a significant decrease in comparison with the OVX group. However, catalase and total antioxidant capacity were significantly lower in the OVX group compared to the sham-operated group, while in the k2OVX group, their activity showed a significant increase in comparison with the OVX group. The OVX group showed a significant elevation in the BAX, BAX/BCl2 ratio, and P53, but BCL2 was significantly reduced. However, the intake of MK-7 caused a significant improvement.

Conclusions

Our study showed that the OVX group showed significant physiological, biochemical, and molecular changes, which can be prevented by MK-7 intake.

Astragalin attenuates depression-like behaviors and memory deficits and promotes M2 microglia polarization by regulating IL-4R/JAK1/STAT6 signaling pathway in a murine model of perimenopausal depression

RATIONALE

Neuroinflammation can be alleviated via M2 microglia polarization, which could promote the recovery of perimenopausal depression. Astragalin (AST) possesses anti-neuroinflammatory activity. However, the effects of AST on perimenopausal depression and the molecular mechanism in regulating microglia polarization remained unknown.

OBJECTIVES

The purpose was to investigate the effects of AST on mice with simulated perimenopausal depression through regulating microglia polarization. It was aimed to clarify the molecular mechanism related to the interleukin-4 receptor (IL-4R)/janus kinase (JAK) 1/signal transducer and activator of transcription (STAT) 6 signaling pathway.

METHODS

The ovariectomy (OVX)/chronic unpredictable mild stress (CUMS)-induced murine model of perimenopausal depression was established and treated with AST. Then the depression-like behaviors and cognitive ability of mice were examined. After that, we detected the markers of microglia polarization and its regulatory signals. In addition, lipopolysaccharides (LPS)/adenosine triphosphate (ATP)-induced inflammatory BV2 model were used to verify the potential molecular mechanism.

RESULTS

AST alleviated perimenopausal depression-like behaviors and memory deficits. AST alleviated microglia activation and increased Ki67-positive cells in dentate gyrus (DG). The viability of BV2 decreased by LPS/ATP was raised by AST. Moreover, both in vivo and in vitro, AST switched microglia from M1 phenotype caused by OVX/CUMS or LPS/ATP to M2 phenotype. The IL-4R/JAK1/STAT6 signaling was restored, and the levels of inducible nitric oxide synthase (iNOS), nuclear NF-KappaB-p65 were reduced by AST. Importantly, AST showed prevention against the ubiquitination modification and degradation of STAT6.

CONCLUSIONS

Our results revealed new insights into molecular mechanism associated with microglia polarization in the effect of AST on the mouse model of perimenopausal depression.

Roles of Fatty Acids in Microglial Polarization: Evidence from In Vitro and In Vivo Studies on Neurodegenerative Diseases

Microglial polarization to the M1 phenotype (classically activated) or the M2 phenotype (alternatively activated) is critical in determining the fate of immune responses in neurodegenerative diseases (NDs). M1 macrophages contribute to neurotoxicity, neuronal and synaptic damage, and oxidative stress and are the first line of defense, and M2 macrophages elicit an anti-inflammatory response to regulate neuroinflammation, clear cell debris, and promote neuroregeneration. Various studies have focused on the ability of natural compounds to promote microglial polarization from the M1 phenotype to the M2 phenotype in several diseases, including NDs. However, studies on the roles of fatty acids in microglial polarization and their implications in NDs are a rare find. Most of the studies support the role of polyunsaturated fatty acids (PUFAs) in microglial polarization using cell and animal models. Thus, we aimed to collect data and provide a narrative account of microglial types, markers, and studies pertaining to fatty acids, particularly PUFAs, on microglial polarization and their neuroprotective effects. The involvement of only PUFAs in the chosen topic necessitates more in-depth research into the role of unexplored fatty acids in microglial polarization and their mechanistic implications. The review also highlights limitations and future challenges.

Microglia in depression: an overview of microglia in the pathogenesis and treatment of depression

Major depressive disorder is a highly debilitating psychiatric disorder involving the dysfunction of different cell types in the brain. Microglia are the predominant resident immune cells in the brain and exhibit a critical role in depression. Recent studies have suggested that depression can be regarded as a microglial disease. Microglia regulate inflammation, synaptic plasticity, and the formation of neural networks, all of which affect depression. In this review, we highlighted the role of microglia in the pathology of depression. First, we described microglial activation in animal models and clinically depressed patients. Second, we emphasized the possible mechanisms by which microglia recognize depression-associated stress and regulate conditions. Third, we described how antidepressants (clinical medicines and natural products) affect microglial activation. Thus, this review aimed to objectively analyze the role of microglia in depression and focus on potential antidepressants. These data suggested that regulation of microglial actions might be a novel therapeutic strategy to counteract the adverse effects of devastating mental disorders.

n-3 PUFA Improve Emotion and Cognition during Menopause: A Systematic Review

Women show an increased risk of cognitive impairment and emotional disorders, such as anxiety and depression, when approaching menopause. Data on risk and protection factors have yielded robust evidence on the effects of lifestyle factors, such as diet, in preserving emotional and cognitive functioning. This review focused on the effects of omega-3 polyunsaturated fatty acids (n-3 PUFA) on anxiety, depression, and cognition during the menopausal transition. This systematic review considered all articles published until 31 December 2021, and the search was performed on two databases, PubMed and Scopus. The fields of interest were "menopause", "n-3 PUFA" and "emotional and cognitive aspects". Out of the 361 articles found on PubMed and 283 on Scopus, 17 met inclusion criteria. They encompassed 11 human and 6 animal studies. Most studies reported relieved depressive symptoms in relation to n-3 PUFA intake. While controversial results were found on anxiety and cognition in humans, n-3 PUFA consistently reduced anxiety symptoms and improved cognition in animal studies. Taken together, n-3 PUFA intake shows beneficial effects on emotional and cognitive behaviours during menopause transition. However, further investigations could increase knowledge about the effectiveness of n-3 PUFA on psychological well-being in this delicate period of feminine life.

Indole-3-Carbinol Selectively Prevents Chronic Stress-Induced Depression-but not Anxiety-Like Behaviors via Suppressing Pro-Inflammatory Cytokine Production and Oxido-Nitrosative Stress in the Brain

Indole-3-carbinol (I3C), a phytochemical enriched in most cruciferous vegetables, has been shown to display various biological activities such as anti-oxidative stress, anti-inflammation, and anti-carcinogenesis. In this study, we investigated the regulatory effect of I3C on chronic stress-induced behavioral abnormalities in mice. Results showed that repeated I3C treatment at the dose of 10, 30, and 60 mg/kg prevented chronic social defeat stress (CSDS)-induced behavioral abnormalities in the tail suspension test, forced swimming test, sucrose preference test, and social interaction test in mice, and did not affect CSDS-induced behavioral abnormalities in the elevated plus maze, light-dark test, and open-field test, suggesting that the I3C treatment selectively prevents the onset of depression- but not anxiety-like behaviors in chronically stressed mice. Further analysis demonstrated that repeated I3C treatment (60 mg/kg, 10 days) prevented CSDS-induced increases in levels of interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) mRNA and protein, but did not affect CSDS-induced decreases in levels of IL-4, IL-10, and Ym-1 mRNA and/or protein in the hippocampus and prefrontal cortex, suggesting that I3C can selectively prevent chronic stress-induced pro-inflammatory but not anti-inflammatory responses in the brain. Further analysis showed that repeated I3C treatment (60 mg/kg, 10 days) prevented CSDS-induced increases in levels of nitrite and malondialdehyde (MDA), decreases in contents of glutathione (GSH), and decreases in levels of brain derived neurotrophic factor (BDNF) protein in the hippocampus and prefrontal cortex. These results demonstrated that I3C selectively prevents chronic stress-induced depression-like behaviors in mice likely through suppressing neuroinflammation and oxido-nitrosative stress in the brain.

Behavioral, Oxidative, and Biochemical Effects of Omega-3 on an Ovariectomized Rat Model of Menopause

OBJECTIVES

Menopause induces changes in neuronal transmission, leading to anxiety and depression. Changes in the brain's glutamate levels cause psychological behavior in postmenopausal women. Omega-3 has been studied to improve some of these behaviors.

METHODS

Twenty-four female Wistar rats were divided into four groups: sham-operated treated with water (SO-W), sham-operated treated with omega-3 (SO-O), ovariectomized (OVX) treated with water (OVX-W), and bilateral OVX treated with omega-3 (OVX-O). These treatments were performed for 20 days via gavage, before and after surgery, totaling 40 days.

RESULTS

In the forced swimming, elevated plus-maze, and open field tests to assess behaviors, such as depression and anxiety, omega-3 improved these behaviors in both treated groups. The levels of thiobarbituric acid reactive substances (TBARS) in the brain were not different between the groups; however, there was a significant decrease in the catalase activity in the SO-O group compared with the SO-W group (P < 0.05). The glutamate level in the cerebrospinal fluid (CSF) was elevated in the SO-O group (P < 0.001) but not in the OVX-W or OVX-O groups.

CONCLUSIONS

These results bring novel data when related to the glutamatergic system in the SO-O group. This has suggested that the action mechanism of omega-3 was not dependent on glutamate levels in the CSF of the OVX group, but it played a regulatory role in the sham-operated animals. To confirm this, more studies are needed to explore this field when relating to the estrogen and glutamate receptor changes in specific brain regions.

The Causal Role of Magnesium Deficiency in the Neuroinflammation, Pain Hypersensitivity and Memory/Emotional Deficits in Ovariectomized and Aged Female Mice

Purpose

Postmenopausal women often suffer from chronic pain, memory decline and mood depression. The mechanisms underlying the neuronal disorders are not fully understood, and effective treatment is still lacking.

Methods

Oral administration of magnesium-L-threonate was tested to treat the neuronal disorders in ovariectomized and aged female mice. The pain hypersensitivity, memory function and depression-like behaviors were measured with a set of behavioral tests. Western blots, immunochemistry and in situ hybridization were used to assess molecular changes.

Results

Chronic oral administration of magnesium-L-threonate substantially prevented or reversed the chronic pain and memory/emotional deficits in both ovariectomized and aged female mice. We found that phospho-p65, an active form of nuclear factor-kappaB, tumor necrosis factor-alpha and interleukin-1 beta were significantly upregulated in the neurons of dorsal root ganglion, spinal dorsal horn and hippocampus in ovariectomized and aged mice. The microglia and astrocytes were activated in spinal dorsal horn and hippocampus. Calcitonin gene–related peptide, a marker for peptidergic C-fibers, was upregulated in dorsal horn, which is associated with potentiation of C-fiber-mediated synaptic transmission in the model mice. In parallel with neuroinflammation and synaptic potentiation, free Mg²⁺ levels in plasma, cerebrospinal fluid and in dorsal root ganglion neurons were significantly reduced. Oral magnesium-L-threonate normalized the neuroinflammation, synaptic potentiation and Mg²⁺ deficiency, but did not affect the estrogen decline in ovariectomized and aged mice. Furthermore, in cultured dorsal root ganglion neurons, estrogen at physiological concentration elevated intracellular Mg²⁺, and downregulated phospho-p65, tumor necrosis factor-alpha and interleukin-1 beta exclusively in the presence of extracellular Mg²⁺.

Conclusion

Estrogen decline in menopause may cause neuroinflammation by reducing intracellular Mg²⁺ in neurons, leading to chronic pain, memory/emotional deficits. Supplement Mg²⁺ by oral magnesium-L-threonate may be a novel approach for treating menopause-related neuronal disorders.

The relevance of the endocrine condition in microglia morphology and dendrite complexity of doublecortin-associated neurons in young adult and middle-aged female rats exposed to acute stress

Menopause, natural or surgical, might facilitate the onset of psychiatric pathologies. Some reports suggest that their severity could increase if the decline of ovarian hormones occurs abruptly and before natural endocrine senescence. Therefore, we compared the effects of ovariectomy on microglia's morphological alterations, the complexity of newborn neurons, and the animal's ability to cope with stress. Young adult (3 months) and middle-aged (15 months) female Wistar rats were subjected to an ovariectomy (OVX) or were sham-operated. After 3 weeks, animals were assigned to one of the following independent groups: (1) young adult OVX + no stress; (2) young adult sham + no stress; (3) young adult OVX + stress; (4) young adult sham + stress; (5) middle-aged OVX + no stress; (6) middle-aged sham + no stress; (7) middle-aged OVX + stress; (8) middle-aged sham + stress. Acute stress was induced by forced swimming test (FST) exposure. Immobility behavior was scored during FST and 30 min after; animals were euthanized, their brains collected and prepared for immunohistochemical detection of Iba-1 to analyze morphological alterations in microglia, and doublecortin (DCX) detection to evaluate the dendrite complexity of newborn neurons. OVX increased immobility behavior, induced microglia morphological alterations, and reduced dendrite complexity of newborn neurons in young adult rats. FST further increased this effect. In middle-aged rats, the main effects were related to the aging process without OVX or stress exposure. In conclusion, surgical menopause favors in young adult rats, but not in middle-aged, the vulnerability to develop immobility behavior, retracted morphology of microglial cells, and decreased dendrite complexity of newborn neurons.

The antidepressant and anxiolytic effect of GPER on translocator protein (TSPO) via protein kinase a (PKA) signaling in menopausal female rats

Postmenopausal depression is mainly caused by the deprivation of ovarian hormones during menopausal transition, it is of great importance to study on the treatment that could effectively relieve symptoms of menopausal depression with fewer side effects. Activation of G-protein-coupled estrogen receptor (GPER) has long been reported to facilitate neuronal plasticity and improve cognition in animals. Meanwhile, it could participate in regulation of intracellular signaling pathways through the characteristic of GPER, ameliorate intracellular mitochondrial function and oxidative stress. However, the impact of GPER on regulating estrogen deprived-depressant and anxious behaviors is still largely unknown. Here we used the ovariectomized female rats to imitate the condition of menopause. Owing to the lateral ventricle administration of G-1 which specifically react with GPER receptor intracerebrally, Ovariectomized (OVX) female rats showed depressive- or anxiety-like phenotypes with attenuated mitochondrial function. In addition, G-1 facilitated PKA activation, which further accelerated TSPO phosphorylation and alleviated menopausal depression- and anxiety-like behaviors. Moreover, PKA inhibitor PKI could partially antagonized the anti-anxiety and anti-depression effects of G-1. Taken together, we concluded that GPER activation might exhibit antidepressant and anxiolytic effect by elevating TSPO phosphorylation via protein kinase A signaling and rescuing the redox status in menopausal female rats.

The impact of phosphodiesterase-5 inhibitor (sildenafil citrate) on some hippocampal neurotransmitters, oxidative stress status, minerals, and anxiety-like behavior in rats

Objective:

The purpose of this work was to investigate the effect of phosphodiesterase type 5 (PDE-5) inhibitor sildenafil citrate (SC) on the level of brain hippocampal neurophysiological parameters (inhibitory and excitatory neurotransmitters), oxidant/antioxidant status, minerals, and anxiety-like behavior using albino male rats.

Materials and methods:

A total of 24 albino male rats were allocated to three separate groups (each one had eight rats): control and SC 5 and 10 mg/kg treatments via i.p. infusion every 3 days for 12 injections. For the behavior of anxiety evaluation, the elevated plus maze test was conducted 1 day after the last treatment, and then all the rats were killed. For serum separation, the blood samples were taken, and hippocampus was dissected from the brain and stored frozen until analysis.

Results:

Both doses of sildenafil significantly improved brain hippocampal neurotransmitter [norepinephrine, serotonin (5-hydroxytryptamine), and gamma-aminobutyric acid] values accompanied by a decreased dopamine level. Interestingly, the SC higher given dose (10 mg/kg) increased the malondialdehyde level with the reduction of the antioxidant parameters [reduced glutathione (GSH) level, catalase (CAT), and superoxide dismutase (SOD) activities] although the lower dose of SC did not cause oxidative stress. Serum and brain hippocampal K, Cu, and Se concentrations were also increased with SC treatments. Moreover, the test of elevated plus maze revealed an anxiolytic impact of sildenafil.

Conclusion:

It was concluded that SC improved the parameters of some hippocampal neurotransmitters and minerals accompanied by anxiolytic impact with the test of elevated plus maze, with a state of oxidative stress revealed with the higher dose of SC which was not recorded with the lower dose.