Absence of Stress Response in Dorsal Raphe Nucleus in Modulator of Apoptosis 1-Deficient Mice

miR-124 mediates the effects of gut microbial dysbiosis on brain function in chronic stressed mice

The gut microbiota plays a key role in the brain function impairment caused by chronic stress, yet its exact mechanism remains unclear. Many studies have revealed the important role of miR-124 in the central nervous system. Meanwhile, previous studies have indicated that miR-124 may be regulated by chronic stress and gut microbiota. Here, we aimed to explore whether miR-124 serves as a mediator for the impacts of gut microbial dysbiosis on brain function in mice subjected to chronic stress. Repeated daily restraint stress for 4 weeks was used to induce chronic stress in mice. Chronic stress resulted in gut microbial dysbiosis, abnormal behaviors, and a decrease in hippocampal miR-124 levels. Treatment with different probiotic mixtures significantly alleviated the effects of chronic stress on hippocampal miR-124 levels and mouse behaviors. Suppression of hippocampal miR-124 expression reversed the beneficial effects of probiotics on cognitive function, neurogenesis, and related molecular markers in chronically stressed mice. Bioinformatics analysis and qPCR suggested that Ptpn11 might be a target gene for miR-124 in mediating the effects of gut microbial dysbiosis on brain function in these mice. These findings suggest that miR-124 is a pivotal regulator that mediates the detrimental effects of gut microbial dysbiosis on brain function and the subsequent cognitive impairment during chronic stress.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Stress-related cellular pathophysiology as a crosstalk risk factor for neurocognitive and psychiatric disorders

In this narrative review, we examine biological processes linking psychological stress and cognition, with a focus on how psychological stress can activate multiple neurobiological mechanisms that drive cognitive decline and behavioral change. First, we describe the general neurobiology of the stress response to define neurocognitive stress reactivity. Second, we review aspects of epigenetic regulation, synaptic transmission, sex hormones, photoperiodic plasticity, and psychoneuroimmunological processes that can contribute to cognitive decline and neuropsychiatric conditions. Third, we explain mechanistic processes linking the stress response and neuropathology. Fourth, we discuss molecular nuances such as an interplay between kinases and proteins, as well as differential role of sex hormones, that can increase vulnerability to cognitive and emotional dysregulation following stress. Finally, we explicate several testable hypotheses for stress, neurocognitive, and neuropsychiatric research. Together, this work highlights how stress processes alter neurophysiology on multiple levels to increase individuals' risk for neurocognitive and psychiatric disorders, and points toward novel therapeutic targets for mitigating these effects. The resulting models can thus advance dementia and mental health research, and translational neuroscience, with an eye toward clinical application in cognitive and behavioral neurology, and psychiatry.

Lactobacillus reuteri ATG-F4 Alleviates Chronic Stress-induced Anhedonia by Modulating the Prefrontal Serotonergic System

Mental health is influenced by the gut-brain axis; for example, gut dysbiosis has been observed in patients with major depressive disorder (MDD). Gut microbial changes by fecal microbiota transplantation or probiotics treatment reportedly modulates depressive symptoms. However, it remains unclear how gut dysbiosis contributes to mental dysfunction, and how correction of the gut microbiota alleviates neuropsychiatric disorders. Our previous study showed that chronic consumption of Lactobacillus reuteri ATG-F4 (F4) induced neurometabolic alterations in healthy mice. Here, we investigated whether F4 exerted therapeutic effects on depressive-like behavior by influencing the central nervous system. Using chronic unpredictable stress (CUS) to induce anhedonia, a key symptom of MDD, we found that chronic F4 consumption alleviated CUS-induced anhedonic behaviors, accompanied by biochemical changes in the gut, serum, and brain. Serum and brain metabolite concentrations involved in tryptophan metabolism were regulated by CUS and F4. F4 consumption reduced the elevated levels of serotonin (5-HT) in the brain observed in the CUS group. Additionally, the increased expression of Htr1a, a subtype of the 5-HT receptor, in the medial prefrontal cortex (mPFC) of stressed mice was restored to levels observed in stress-naïve mice following F4 supplementation. We further demonstrated the role of Htr1a using AAV-shRNA to downregulate Htr1a in the mPFC of CUS mice, effectively reversing CUS-induced anhedonic behavior. Together, our findings suggest F4 as a potential therapeutic approach for relieving some depressive symptoms and highlight the involvement of the tryptophan metabolism in mitigating CUS-induced depressive-like behaviors through the action of this bacterium.

A signalling pathway for transcriptional regulation of sleep amount in mice

In mice and humans, sleep quantity is governed by genetic factors and exhibits age-dependent variation1-3. However, the core molecular pathways and effector mechanisms that regulate sleep duration in mammals remain unclear. Here, we characterize a major signalling pathway for the transcriptional regulation of sleep in mice using adeno-associated virus-mediated somatic genetics analysis4. Chimeric knockout of LKB1 kinase-an activator of AMPK-related protein kinase SIK35-7-in adult mouse brain markedly reduces the amount and delta power-a measure of sleep depth-of non-rapid eye movement sleep (NREMS). Downstream of the LKB1-SIK3 pathway, gain or loss-of-function of the histone deacetylases HDAC4 and HDAC5 in adult brain neurons causes bidirectional changes of NREMS amount and delta power. Moreover, phosphorylation of HDAC4 and HDAC5 is associated with increased sleep need, and HDAC4 specifically regulates NREMS amount in posterior hypothalamus. Genetic and transcriptomic studies reveal that HDAC4 cooperates with CREB in both transcriptional and sleep regulation. These findings introduce the concept of signalling pathways targeting transcription modulators to regulate daily sleep amount and demonstrate the power of somatic genetics in mouse sleep research.

Long Noncoding RNA LINC00473 Ameliorates Depression-Like Behaviors in Female Mice by Acting as a Molecular Sponge to Regulate miR-497-5p/BDNF Axis

Background. Depression was a common life-threatening psychiatric disorder and occurs more frequently in women than in men. Long noncoding RNAs (lncRNAs), such as LINC00473, had been reported to be involved in the progression of depression. Methods. Chronic unpredictable moderate stress in mice (CUMS) was applied to construct a depression model. Subsequently, RT-qPCR was applied to check the level of LINC00473 and microRNA-497-5p (miR-497-5p) in the hippocampal region of the mice induced by CUMS. CUMS mice were injected with lentiviral vectors of LINC00473 (LV-LINC00473), miR-497-5p inhibitor, short hairpin- (sh-) brain-derived neurotrophic factor (sh-BDNF), or miR-497-5p mimic to evaluate depressive behaviors, including sucrose preference test, forced swim test, elevated plus maze, and tail suspension test. Moreover, the production of hypothalamic neurotransmitters was assessed with the usage of ELISA kits. Dual-luciferase reporter assay, RNA pull-down, and RIP analysis were performed to measure the relationship between miR-497-5p and LINC00473 or BDNF. Further, western blot was employed to determine the protein level of BDNF. Results. We discovered that LINC00473 level was downregulated in the female mice with depression, but not in male mice. Besides, the depressive behaviors induced by CUMS in mice, including the decrease of sucrose preference and time in open arm, as well as the increase of immobility time and swimming resting time were all ameliorated by LINC00473 overexpression. Moreover, the concentration of neurotransmitters was decreased in CUMS-induced mouse hypothalamus, which was blocked by LV-LINC00473 lentiviral vector administration. Mechanistically, LINC00473 directly targeted miR-497-5p. Absence of miR-497-5p revealed the antidepression effects on CUMS-induced mice, and miR-497-5p upregulation could counter the antidepressive impacts of LINC00473 upregulation on CUMS-induced mice. Furthermore, LINC00473 could target miR-497-5p to modulate BDNF level. Knockdown of BDNF could abrogate the improving influences of miR-497-5p suppression on CUMS-induced depression. Conclusions. LINC00473 ameliorated CUMS-caused depression by encouraging BDNF expression via binding to miR-497-5p, which might provide a potential therapeutic target for depression in females.

Hippocampal miR-124 Participates in the Pathogenesis of Depression via Regulating the Expression of BDNF in a Chronic Social Defeat Stress Model of Depression

OBJECTIVE

As one of the most prevalent psychiatric disorders, the exact pathogenesis of depression remains elusive. Therefore, there is an urgent need to identify novel antidepressants for effective treatment. MicroRNA-124 (miR-124), the most abundant miRNA in brain tissue, plays a key effect on adult neurogenesis and neuronal differentiation. However, the mechanism of miR-124 in depression has not been clarified so far. The aim of this study is to provide broad insight into the mechanisms underlying depression.

METHODS

In the study, we used the forced swim test (FST), the tail suspension test (TST), and a Chronic Social Defeat Stress (CSDS) mice model of depression. Quantitative real-time reverse transcription PCR (qRT-PCR), western blotting, immunofluorescence and virus-mediated gene transfer were used together. The level of plasma corticosterone in mice was analyzed by Enzyme Linked Immunosorbent Assay (ELISA).

RESULTS

It was found that CSDS robustly increased the level of miR-124 in the hippocampus. Genetic knockdown of hippocampal miR-124 produced significant antidepressant-like effects in the CSDS model of depression. Furthermore, AAV-siR-124-EGFP treatment increased the level of plasma corticosterone in CSDS-induced mice. Moreover, it was found that the antidepressant-like effects induced by miR-124 inhibition required the hippocampal BDNF-TrkB system.

CONCLUSION

Hippocampal miR-124 participated in the pathogenesis of depression by regulating BDNF biosynthesis and was a feasible antidepressant target.

Revealing the Roles of MOAP1 in Diseases: A Review

Modulator of apoptosis protein1 (MOAP1), also known as MAP1 and PNMA4, belongs to the PNMA gene family consisting of at least 15 genes located on different chromosomes. MOAP1 interacts with the BAX protein, one of the most important apoptosis regulators. Due to its critical role in a few of disease-associated pathways, MOAP1 is associated with many diseases such as cancers and neurological diseases. In this study, we introduced MOAP1 and its biological functions and reviewed the associations between MOAP1 and a few diseases including cancers, neurological diseases, and other diseases such as inflammation and heart diseases. We also explained possible biological mechanisms underlying the associations between MOAP1 and these diseases, and discussed a few future directions regarding MOAP1, especially its potential roles in neurodegenerative disorders. In summary, MOAP1 plays a critical role in the development and progression of cancers and neurological diseases by regulating a few genes related to cellular apoptosis such as BAX and RASSF1A and interacting with disease-associated miRNAs, including miR-25 and miR1228.

Knockdown of miR-124 Reduces Depression-like Behavior by Targeting CREB1 and BDNF

OBJECTIVE

As a brain-specific microRNA, the mechanism of miR-124 in depression has not been clarified so far. The present study aimed to explore the role of miR-124 in depression and its potential targets.

METHODS

The depression model was first replicated by the chronic unpredictable mild stress (CUMS) method. miR-124 antagomir was injected into the hippocampus of CUMS rats. Sucrose preference test (SPT), open-field test (OFT), elevated-plus maze (EPM), and forced swimming test (FST) were used to analyze the depression-like behavior. The content of norepinephrine (NE), dopamine (DA) and 5-hydroxytryptamine (5-HT) in the hypothalamus was analyzed by ELISA. qRT-PCR and western blot assay were used for functional analysis.

RESULTS

miR-124 expression was up-regulated in the hippocampus of CUMS -induced depression model rats, while CREB1 and BDNF were down-regulated. Administration of miR-124 antagomir in the hippocampus inhibited miR-124 expression in the hippocampus of CUMS rats. Additionally, SPT, OFT, EPM, and FST also showed that miR-124 antagomir can reduce the depression-like behavior of CUMS rats. Furthermore, miR-124 antagomir injection increased the levels of NE, DA and 5-HT in the hypothalamus of CUMS rats. Moreover, miR-124 antagomir injection increased the expression of cyclic AMP-responsive element-binding protein1 (CREB1) and brain-derived neurotrophic factor (BDNF) in the hippocampus. Using the dual-luciferase reporter assay, it was confirmed that miR-124 directly targets 3'UTR of CREB1 and BDNF genes.

CONCLUSION

Knockdown of miR-124 can improve depression-like behavior in CUMS-induced depressive rats, which may be related at least in part to the up-regulation of CREB1 and BDNF expression in the hippocampus.