Mesolimbic dopamine system and its modulation by vitamin D in a chronic mild stress model of depression in the rat

Empagliflozin alleviates diabetes-induced cognitive impairments by lowering nicotinamide adenine dinucleotide phosphate oxidase-4 expression and potentiating the antioxidant defense system in brain tissue of diabetic rats

BACKGROUND

Diabetes-induced cognitive impairment is a major challenge in patients with uncontrolled diabetes mellitus. It has a complicated pathophysiology, but the role of oxidative stress is central. Therefore, the use of antidiabetic drugs with extra-glycemic effects that reduce oxidative damage may be a promising treatment option.

METHODS

Male Wistar rats were randomly divided into four groups as normal, normal treated, diabetic and diabetic treated (n = 8 per group). Type 1 diabetes was induced by a single intraperitoneal dose of streptozotocin (STZ) (40 mg/kg). Two treatment groups received empagliflozin for 5 weeks (20 mg/kg/po). Cognitive ability was evaluated using open field, Elevated Plus Maze (EPM) and the Morris Water Maze (MWM) tests at study completion. Blood and brain tissue samples were collected - and analysis for malondialdehyde (MDA) and glutathione (GLT) content and catalase (CAT) and superoxide dismutase (SOD) enzyme activity were performed. Additionally, expression of nicotinamide adenine dinucleotide phosphate oxidase-4 (Nox-4) enzyme in brain tissue was analyzed using RT-PCR.

RESULTS

STZ increased blood glucose and induced diabetes with oxidative stress by lowering the antioxidant system potency and increasing Nox-4 expression after 5-weeks in brain tissue accompanied by reduction in cognitive performance. Also, diabetes induced anxiety-like behavior and impaired spatial memory in MWM, EPM and open field tests. However, empagliflozin reversed these changes, improving SOD and CAT activity, GLT content and reducing Nox-4 expression and MDA concentration in brain tissue while improving cognitive ability. It reduced anxiety and depression-related activities. It also improved spatial memory in MWM test.

CONCLUSION

Uncontrolled diabetes negatively impacts mental function and impairs learning and cognitive performance via oxidative stress induction, the Nox-4 enzyme playing a central role. Empagliflozin reverses these effects, improving cognitive ability via promoting the anti-oxidative system and damping Nox-4 free radical generator enzyme expression. Therefore, empagliflozin is a promising treatment, providing both antidiabetic and extra-glycemic benefits for improving brain function in the diabetic milieu.

Vitamin D3 improves iminodipropionitrile-induced tic-like behavior in rats through regulation of GDNF/c-Ret signaling activity

Children with chronic tic disorders (CTD), including Tourette syndrome (TS), have significantly reduced serum 25-hydroxyvitamin D [25(OH)D]. While vitamin D3 supplementation (VDS) may reduce tic symptoms in these children, its mechanism is unclear. The study aim was to investigate the effects and mechanisms of vitamin D deficiency (VDD) and VDS on TS model behavior. Forty 5-week-old male Sprague-Dawley rats were randomly divided into (n = 10 each): control, TS model, TS model with VDD (TS + VDD), or TS model with VDS (TS + VDS; two intramuscular injections of 20,000 IU/200 g) groups. The VDD model was diet-induced (0 IU vitamin D/kg); the TS model was iminodipropionitrile (IDPN)-induced. All groups were tested for behavior, serum and striatal 25(OH)D and dopamine (DA), mRNA expressions of vitamin D receptor (VDR), glial cell line-derived neurotrophic factor (GDNF), protooncogene tyrosine-protein kinase receptor Ret (c-Ret), and DA D1 (DRD1) and D2 (DRD2) receptor genes in the striatum. TS + VDD had higher behavior activity scores throughout, and higher total behavior score at day 21 compared with TS model. In contrast, day 21 TS + VDS stereotyped behavior scores and total scores were lower than TS model. The serum 25(OH)D in TS + VDD was < 20 ng/mL, and lower than control. Striatal DA of TS was lower than control. Compared with TS model, striatal DA of TS + VDD was lower, while in TS + VDS it was higher than TS model. Furthermore, mRNA expression of VDR, GDNF, and c-Ret genes decreased in TS model, and GDNF expression decreased more in TS + VDD, while TS + VDS had higher GDNF and c-Ret expressions. VDD aggravates, and VDS ameliorates tic-like behavior in an IDPN-induced model. VDS may upregulate GDNF/c-Ret signaling activity through VDR, reversing the striatal DA decrease and alleviating tic-like behavior.

The role of amygdala-ventral pallidum pathway in depression-like behaviors in male mice

The basolateral amygdala (BLA) appears to serve an important function in the pathophysiology of depression. Depressive symptoms, such as anhedonia are largely caused by dysfunction in the brain's reward system, in which the ventral pallidum (VP) participates in by controlling dopamine release. However, the role of the BLA-VP pathway in the development of depression remains poorly understood. To investigate this pathway, we employed the Chronic Unpredictable Mild Stress (CUMS) mouse model, in which we injected retroAAV expressing GFP-Cre into the VP and AAV expressing hM4Di-mCherry into the BLA. We then used CNO to activate the Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) for all behavioral tests. The CUMS procedure resulted in significant depression symptoms such as decreased sucrose preference, limited weight gain, decreased immobile latency, and increased immobile time in the forced swim and tail suspension tests. Inhibition of the BLA-VP glutamatergic projections reversed these depression-like behaviors. We found that suppressing the BLA-VP circuitry had beneficial effects on CUMS-induced depression-like behaviors such as anorexia, anhedonia, and despair. Specifically, upon suppression of glutamatergic projections in the BLA-VP circuitry, these depression-like behaviors were significantly alleviated, which highlights the vital role of this circuitry in the development of depression. Furthermore, the beneficial effects of suppressing this circuitry seem to be associated with the brain's reward system, warranting further investigation.

Vitamin D and depression in older adults: lessons learned from observational and clinical studies

Depression is a mental disorder triggered by the interaction of social, psychological and biological factors that have an important impact on an individual's life. Despite being a well-studied disease with several established forms of treatment, its prevalence is increasing, especially among older adults. New forms of treatment and prevention are encouraged, and some researchers have been discussing the effects of vitamin D (VitD) on depression; however, the exact mechanism by which VitD exerts its effects is not yet conclusive. In this study, we aimed to discuss the possible mechanisms underlying the association between VitD and depression in older adults. Therefore, we conducted a systematic search of databases for indexed articles published until 30 April 2021. The primary focus was on both observational studies documenting the association between VitD and depression/depressive symptoms, and clinical trials documenting the effects of VitD supplementation on depression/depressive symptoms, especially in older adults. Based on pre-clinical, clinical and observational studies, it is suggested that the maintenance of adequate VitD concentrations is an important issue, especially in older adults, which are a risk population for both VitD deficiency and depression. Nevertheless, it is necessary to carry out more studies using longitudinal approaches in low- and middle-income countries to develop a strong source of evidence to formulate guidelines and interventions.

Severe Vitamin D Deficiency-A Possible Cause of Resistance to Treatment in Psychiatric Pathology

In the last few years, vitamin D functions have been studied progressively, and along with their main role in regulating calcium homeostasis, the potential function in the nervous system and the link between different psychiatric disorders and vitamin D deficiency have been revealed. The discovery of vitamin D receptors in multiple brain structures, like the hippocampus, led to the hypothesis that vitamin D deficiency could be responsible for treatment resistance in psychiatric diseases. The aim of this study was to analyze the current knowledge in the literature regarding vitamin D deficiency among individuals afflicted with psychiatric disorders and assess the potential therapeutic benefits of vitamin D supplementation. A systematic search was conducted on the PubMed database for articles published in the last five years (2016-2022) in English, focusing on human subjects. Results show that vitamin D deficiency has implications for numerous psychiatric disorders, affecting mood and behavior through its influence on neurotransmitter release, neurotrophic factors, and neuroprotection. It also plays a role in modulating inflammation, which is often elevated in psychiatric disorders. In conclusion, vitamin D deficiency is prevalent and has far-reaching implications for mental health. This review underscores the importance of exploring the therapeutic potential of vitamin D supplementation in individuals with psychiatric disorders and highlights the need for further research in this complex field.

The effect of vitamin D supplementation on depressive symptoms in adults: A systematic review and meta-analysis of randomized controlled trials

Neurosteroid and immunological actions of vitamin D may regulate depression-linked physiology. Meta-analyses investigating the effect of vitamin D on depression have been inconsistent. This meta-analysis investigated the efficacy of vitamin D in reducing depressive symptoms among adults in randomized placebo-controlled trials (RCT). General and clinical populations, and studies of ill individuals with systemic diseases were included. Light therapy, co-supplementation (except calcium) and bipolar disorder were exclusionary. Databases Medline, PsycINFO, CINAHL and The Cochrane Library were searched to identify relevant articles in English published before April 2022. Cochrane risk-of-bias tool (RoB 2) and GRADE were used to appraise studies. Forty-one RCTs (n = 53,235) were included. Analyses based on random-effects models were performed with the Comprehensive Meta-analysis Software. Results for main outcome (n = 53,235) revealed a positive effect of vitamin D on depressive symptoms (Hedges' g = -0.317, 95% CI [-0.405, -0.230], p < 0.001, I2 = 88.16%; GRADE: very low certainty). RoB assessment was concerning in most studies. Notwithstanding high heterogeneity, vitamin D supplementation ≥ 2,000 IU/day appears to reduce depressive symptoms. Future research should investigate possible benefits of augmenting standard treatments with vitamin D in clinical depression. PROSPERO registration number: CRD42020149760. Funding: Finnish Medical Foundation, grant 4120 and Juho Vainio Foundation, grant 202100353.

Attenuation of morphine conditioned place preference and reinstatement by vitamin D

Opioid action in the brain involves the dopamine-reward system as well as non-dopamine pathways. Since vitamin D also modulates the brain's dopamine system, the question of this study was how vitamin D might affect the opioid influences on the reward system. Therefore, the objective of this study was to investigate the possible effect of vitamin D on the conditioned place preference (CPP) induced by morphine, as a valuable model of assessment of the reinforcing properties of opioids by associating the context to the rewarding properties of the addictive drugs. Male Wistar rats were randomly divided into two main groups that either received saline (morphine vehicle) or morphine (5 mg/kg, intraperitoneally) for CPP. Each of the main groups was divided into three vitamin D treatment subgroups: vitamin D vehicle and vitamin D (5 and 10 μg/kg, intraperitoneally). Vitamin D injections were started 1 week ahead of the experiment (two injections) or immediately after post-conditioning and in both cases, it was continued twice weekly throughout the CPP. Administration of vitamin D (10 μg/kg) before conditioning in CPP markedly attenuated morphine expression in the post-conditioning test. Receiving vitamin D (5 or 10 μg/kg) before or after conditioning significantly attenuated morphine reinstatement. Administration of vitamin D after opioid conditioning facilitated morphine memory extinction and attenuated morphine reinstatement. Vitamin D is probably a valuable addition to be considered as a part of the treatment for prevention or minimizing the dependency or relapse to opioids.

Electroacupuncture alleviated depression‐like behaviors in ventromedial prefrontal cortex of chronic unpredictable mild stress‐induced rats: Increasing synaptic transmission and phosphorylating dopamine transporter

AIMS

Electroacupuncture (EA) shows advantages in both clinical practice and depression animal models. Dopaminergic-related dysfunction in the prefrontal cortex (PFC) may be a hidden antidepressant mechanism of EA, where dopamine transporter (DAT) plays an essential role. This study aimed to investigate the synaptic transmission and DAT-related changes of EA in depression.

METHODS

Male Sprague-Dawley rats were subjected to 3-week chronic unpredictable mild stress (CUMS). The successfully modeled rats were then randomly and equally assigned to CUMS, selective serotonin reuptake inhibitor (SSRI), and EA or SSRI + EA groups, followed by a 2-week treatment respectively. After monitoring body weight and behavioral tests of all rats, the ventromedial PFC (vmPFC) tissue was collected for electrophysiology and the expression detection of DAT, phosphorylated DAT (p-DAT), cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), and trace amine-associated receptor 1 (TAAR1).

RESULTS

Depressive-like behaviors induced by CUMS were alleviated by EA, SSRI, and SSRI + EA treatments through behavioral tests. Compared with CUMS group, EA improved synaptic transmission in vmPFC by upregulating spontaneous excitatory postsynaptic currents amplitude. Molecularly, EA reversed the increased total DAT and p-DAT expression as well as the decreased ratio of p-DAT/total DAT along with the activation of TAAR1, cAMP, and PKA in vmPFC.

CONCLUSION

We speculated that the antidepressant effect of EA was associated with enhanced synaptic transmission in vmPFC, and the upregulated phosphorylation of DAT relevant to TAAR1, cAMP, and PKA may be the potential mechanism.

Vitamin D and the Central Nervous System: Causative and Preventative Mechanisms in Brain Disorders

Twenty of the last one hundred years of vitamin D research have involved investigations of the brain as a target organ for this hormone. Our group was one of the first to investigate brain outcomes resulting from primarily restricting dietary vitamin D during brain development. With the advent of new molecular and neurochemical techniques in neuroscience, there has been increasing interest in the potential neuroprotective actions of vitamin D in response to a variety of adverse exposures and how this hormone could affect brain development and function. Rather than provide an exhaustive summary of this data and a listing of neurological or psychiatric conditions that vitamin D deficiency has been associated with, here, we provide an update on the actions of this vitamin in the brain and cellular processes vitamin D may be targeting in psychiatry and neurology.

Regulatory Role of PFC Corticotropin-Releasing Factor System in Stress-Associated Depression Disorders: A Systematic Review

Stress has a substantial role in formation of psychiatric disorders especially depression. Meanwhile, impairment of the prefrontal cortex (PFC) is connected to the executive and cognitive deficits induced by the stress. Given the involvement of the corticotropin-releasing factor (CRF) in stress-related processes and knowing the fact that PFC hosts a lot of CRF receptors and CRF neurotransmissions, it can worth to look at the CRF as a potential treatment for the regulation of depression disorders induced by stress within PFC region. Here, for the first time we aimed to systematically review the effectiveness of intra-PFC CRF system in the modulation of depression dysfunction caused by the stress in clinical and preclinical models/studies. Qualified researches were combined utilizing a comprehensive search of six databases including Scopus, Pubmed, Web of Science, Sciencedirect, APA PsycNet, and Embase in April 2021 and were evaluated through proper methodological quality assessment tools. Results indicate that PFC has a remarkable role in the modulation for stress-induced depression and intra-PFC CRF receptors agonist and antagonist are very considerable for regulating these types of impairments. Specifically, elevation of both CRF immunoreactivity and gene expression were observed in human studies. In the animal studies, mostly immunoreactivity or excitatory/inhibitory currents of CRF within the PFC regulated depression dysfunction. In conclusion, reviewed studies show a positive attitude toward the CRF system in regulation of the stress-induced depression; however, obviously further investigations are required to get closer to the best treatment. Prefrontal cortex corticotropin-releasing factor system regulates stress-induced depression. CRFR1, Corticotropin-releasing factor receptor of type1; PFC, Prefrontal cortex; Minus (-) and Plus (+) signs, dysregulation and upregulation, respectively.

Gene Expression Profile Associated with Asmt Knockout-Induced Depression-Like Behaviors and Exercise Effects in Mouse Hypothalamus

Sleep disorder caused by abnormal circadian rhythm is one of the main symptoms and risk factors of depression. As a known hormone regulating circadian rhythms, melatonin (MT) is also namely N-acetyl-5-methoxytryptamine. N-acetylserotonin methyltransferase (Asmt) is the key rate-limiting enzyme of MT synthesis and has been reportedly associated with depression. Although 50–90% of patients with depression have sleep disorders, there are no effective treatment ways in the clinic. Exercise can regulate circadian rhythm and play an important role in depression treatment. In the present study, we showed that Asmt knockout induced depression-like behaviors, which were ameliorated by swimming exercise. Moreover, swimming exercise increased serum levels of MT and 5-hydroxytryptamine (5-HT) in Asmt knockout mice. In addition, the microarray data identified 10 differentially expressed genes (DEGs) in KO mice compared with WT mice and 29 DEGs in KO mice after swimming exercise. Among the DEGs, the direction and magnitude of change in epidermal growth factor receptor pathway substrate 8-like 1 (Eps8l1) and phospholipase C-β 2 (Plcb2) were confirmed by qRT-PCR partly. Subsequent bioinformatic analysis showed that these DEGs were enriched significantly in the p53 signaling pathway, long-term depression and estrogen signaling pathway. In the protein–protein interaction (PPI) networks, membrane palmitoylated protein 1 (Mpp1) and p53-induced death domain protein 1 (Pidd1) were hub genes to participate in the pathological mechanisms of depression and exercise intervention. These findings may provide new targets for the treatment of depression.

EMF promote BMSCs differentiation and functional recovery in hemiparkinsonian rats

Bone marrow mesenchymal stem cells (BMSCs) have self-renewal ability while maintaining the proliferation facility. The BMSCs reproducing ability could affect by electromagnetic fields (EMFs) as a physical inducing factor. We focused on the EMF (400 µT, 75 Hz) exposed multi-potential BMSCs which differentiated and successfully implanted in the substantia nigra pars compacta (SNpc) of Parkinson's disease rat model. The purified BMSCs are exposed to sinusoidal and square waveform EMF (1h/1 week or 7h/1 day) then injected into the left SNpc of Parkinson's rats. To evaluate the morphology of EMF exposed BMSCs, the cresyl violet staining labeled the Nissl bodies. After evaluation of the rat's activity by behavioral tests (open-field and rotarod tests), the brains were obtained for the preparation of SNpc blocks and carry out the cresyl violet staining. Cell morphology proved most cell differentiation to neurons in the sinusoidal EMF groups. In the sinusoidal EMF exposure groups, large and small neurons were seen with apparent synapses. Although in the square EMF exposed groups some neurons were seen, most of the differentiated cells were astrocytes, microglia, and oligodendrocyte. The results confirmed an improvement in locomotors' activity of BMSC alone and sinusoidal EMF exposed groups. We presented a low-frequency EMF (75 Hz) to promote the capability of BMSC proliferation, differentiation to neurons and glial cells, and motor coordination activity in the treatment of hemiparkinsonian rats.

COVID-19 and neurological sequelae: Vitamin D as a possible neuroprotective and/or neuroreparative agent

SARS-CoV-2, the etiological agent of the current COVID-19 pandemic, belongs to a broad family of coronaviruses that also affect humans. SARS-CoV-2 infection usually leads to bilateral atypical pneumonia with significant impairment of respiratory function. However, the infectious capacity of SARS-CoV-2 is not limited to the respiratory system, but may also affect other vital organs such as the brain. The central nervous system is vulnerable to cell damage via direct invasion or indirect virus-related effects leading to a neuroinflammatory response, processes possibly associated with a decrease in the activity of angiotensin II converting enzyme (ACE2), the canonical cell-surface receptor for SARS-CoV-2. This enzyme regulates neuroprotective and neuroimmunomodulatory functions and can neutralize both inflammation and oxidative stress generated at the cellular level. Furthermore, there is evidence of an association between vitamin D deficiency and predisposition to the development of severe forms of COVID-19, with its possible neurological and neuropsychiatric sequelae: vitamin D has the ability to down-modulate the effects of neuroinflammatory cytokines, among other anti-inflammatory/immunomodulatory effects, thus attenuating harmful consequences of COVID-19. This review critically analyzes current evidence supporting the notion that vitamin D may act as a neuroprotective and neuroreparative agent against the neurological sequelae of COVID-19.

Naringenin Improves Ovalbumin-Induced Allergic Asthma in Rats through Antioxidant and Anti-Inflammatory Effects

Asthma is a chronic disease with eosinophilic inflammation and oxidative damages leading to airway obstruction. Naringenin is a phytochemical possessing strong antioxidant and anti-inflammatory activities against chronic destructive conditions. The current study is devoted to evaluating naringenin's effects on the attenuation of inflammation and oxidative stress in lung tissue in a rat model of ovalbumin-induced asthma. Male Wistar rats were allocated to five groups of six: normal control (NC, receiving 1 ml/day of normal saline, orally), asthmatic (AS, receiving ovalbumin (1 mg/mL), and alum (1 mg/mL in saline) on days 0 and 14. Then, on days 21, 22, and 23, they were sensitized with the inhalation of ovalbumin), AS treated with dexamethasone (AS, 1 mg/kg/day, orally) [AS + D1], AS treated with naringenin (20 mg/kg/day, orally) [AS + N20], and AS treated with naringenin (40 mg/kg/day, orally) [AS + N40]. All the groups received associated drugs/agents for 28 days. Finally, bronchoalveolar lavage fluid (BALF) and lung tissue samples were taken off from the animals. The eosinophil count in BALF and malondialdehyde (MDA), glutathione (GSH), interleukin-13 and -4 (IL-13 and IL-4) levels were measured. Besides, the expression of urocortin (UCN) and surfactant protein-D (SP-D) were evaluated in the lung tissue using immunohistochemistry (IHC) and western blotting methods, respectively. Hematoxylin and eosin (H&E) staining were utilized to conduct histopathological analysis. Naringenin treatment significantly reduced MDA, remarkably increased GSH, and meaningfully reduced IL-4 and IL-13 levels in lung tissue. The count of eosinophils in the BALF of AS + N20 and AS + N40 was significantly reduced in comparison with the AS group. The UCN and SP-D protein levels were significantly decreased in the AS + N20 and AS + N40 groups compared to the AS group, using the IHC and western blot methods, respectively. Histopathological analysis data also confirm the results. Naringenin improves the symptoms of allergic asthma through antioxidant and anti-inflammatory effects.

Is Vitamin D Important in Anxiety or Depression? What Is the Truth?

PURPOSE OF REVIEW

Depression and anxiety are mood disorders that affect health and therefore quality of life and increase the global burden of disease. One of the possible mechanisms in the pathophysiology of these mood disorders has been reported as oxidative stress and inflammation. In the light of this information, it is important to determine the relationship between antioxidant nutrients (such as vitamin D) and these diseases. There are points where the brain regions involved in the pathophysiology of depression and anxiety and vitamin D metabolism intersect.

RECENT FINDINGS

Low vitamin D levels are associated with increased symptoms of depression and anxiety. For this reason, vitamin D screening should be performed in the prevention and treatment planning of these mood disorders. Vitamin D, which has antioxidant properties and activity in brain tissue, is important for mood disorders preventions or treatments but serum levels must be followed.

Regulatory effect of vitamin D on pro-inflammatory cytokines and anti-oxidative enzymes dysregulations due to chronic mild stress in the rat hippocampus and prefrontal cortical area

BACKGROUND

Chronic stress increases the production of pro-inflammatory cytokines and oxidative stress in the brain, which underlay cognitive and psychological problems. In addition to the anti-depressants, vitamin D is known to act as an anti-inflammatory and anti-oxidative agent. This study investigates the specific effects of vitamin D in protecting hippocampus and pre-frontal cortex (PFC) against chronic mild stress (CMS)-induced activation of pro-inflammatory cytokines IL-6 and TNF-α and decreasing the activation of anti-oxidative enzymes super oxide dismutase (SOD) and glutathione peroxidase (GPx).

METHODS AND RESULTS

Rats were exposed to CMS for 3 weeks. Two groups of rats received vitamin D (5 and 10 μg/kg) and another received fluoxetine (5 mg/kg) along with CMS. Control groups were not exposed to CMS, but received treatments similar to CMS groups. Serum corticosterone and IL-6, TNF-α and SOD and GPx levels in the hippocampus and PFC were measured at the end of three weeks. CMS significantly increased corticosterone, IL-6, TNF-α and decreased SOD and GPx levels (P < 0.0001) in hippocampus and PFC. Vitamin D treatment reduced corticosterone levels (P < 0.01), increased SOD (P < 0.0001) and GPx (P < 0.01) and decreased IL-6 and TNF-α (P < 0.0001) levels in the hippocampus and PFC compared to rats treated with vitamin D vehicle. Vitamin D-10 regulation of SOD and IL-6 levels was more effective than fluoxetine (P < 0.0001 and P < 0.01, respectively, in hippocampus).

CONCLUSION

This study suggests that vitamin D effectively protects the key regions of the brain related to cognition and affective behavior, against the inflammation and oxidative stress caused by the chronic stress.

The role of SIRT1 in the basolateral amygdala in depression-like behaviors in mice

Previous investigations have implicated the basolateral amygdala (BLA) epigenetic mechanisms in the pathophysiology of depression. SIRT1 is a NAD+-dependent class III histone deacetylase, widely expresses in BLA. However, epigenetic mechanisms in the BLA under the regulation of SIRT1 in the depression are largely uncharacterized. Under the chronic unpredictable chronic mild stress (CUMS) mouse model, we used adeno-associated viral vectors (AAV) that encoded SIRT1-shRNA or SIRT1 to specifically knockdown or overexpress SIRT1 in BLA neurons, respectively. CUMS procedure induced significant depression symptoms including the decreased sucrose preference, the less bodyweight gained, the decreased immobile latency and the increased immobile time both in forced swim test (FST) and tail suspension test (TST). Knockdown of SIRT1 in BLA glutamatergic neurons reversed these depression-like behaviors and restored the synaptic abnormalities. Overexpression of SIRT1 in BLA glutamatergic neurons induced depression-like behaviors in non-stressed control mice. The result of protein expressions and ultrastructural changes were consistent with the behavioral results. Our study suggested that downregulation of SIRT1 in BLA has certain beneficial effect on CUMS-induced depression-like behaviors such as anorexia, anhedonia, hopelessness and despair. In addition, the increased expression of SIRT1 may be the immediate cause of depressive-like symptoms. The abnormal expression of SIRT1 may affect the transcriptional regulation mechanism and signaling protein acetylation, affecting neuroplasticity and ultimately contribute to MDD. In the stress-susceptible mice, these two mechanisms may co-exist, but the specific mechanism needs further research.

Antidepressant mechanism of catalpol: Involvement of the PI3K/Akt/Nrf2/HO-1 signaling pathway in rat hippocampus

Catalpol is a major compound in Rehmanniae Radix with outstanding medicinal and nutritional values. Our previous studies have demonstrated catalpol's antidepressant effect, but its mechanisms remain unclear. This study aimed to explore the antidepressant mechanisms of catalpol via the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/nuclear factor E2-related factor 2(Nrf2)/heme oxygenase-1 (HO-1) pathway. Results demonstrated that chronic unpredictable mild stress (CUMS) for 5 consecutive weeks caused significant decreases in the sucrose preference and the horizontal and vertical scores of open-field test, as well as a significant increase in the swimming-immobility time of rats; catalpol administration significantly reversed the abnormality of these indicators. Further real-time fluorescent quantitative polymerase chain reaction and Western blotting results together showed that CUMS significantly downregulated the expression levels of hippocampal genes and proteins, including PI3K, Akt, Nrf2, HO-1, tropomyosin-related kinase B (TrkB), and brain-derived neurotrophic factor; catalpol administration significantly reversed the abnormal expression of these genes and proteins. CUMS also caused a significant decrease in the hippocampal superoxide dismutase, catalase, glutathione peroxidase, glutathione-s transferase, and reduced glutathione levels, as well as a significant increase in thiobarbituric acid reactive substances level in rats; catalpol administration significantly reversed the abnormality of these indicators. Taken together, this study confirmed for the first time that the antidepressant effect of catalpol on CUMS-induced depression involved the upregulation of the PI3K/Akt/Nrf2/HO-1 signaling pathway, thereby improving the hippocampal neurotrophic, neuroprotective, and antioxidant levels. The PI3K/Akt/Nrf2/HO-1 pathway-related molecules may serve as potential new biomarkers and candidate molecular targets for catalpol's antidepressant effects.

Vitamin D: A Pleiotropic Hormone with Possible Psychotropic Activities

BACKGROUND

After the recognition of the efficacy of cod-liver oil in rickets at the end of the eighteenth century, and the isolation and synthesis of the liposoluble vitamin D in 1931, its mode of actions and functions were deeply explored. Biochemical studies permitted to identify five forms of vitamin D, called D1, D2, D3, D4 and D5, differing in ultrastructural conformation and origin, with vitamin D2 (ergocalciferol) and D3 (cholecalciferol) representing the active forms. In the last decades especially, a constantly increasing bulk of data highlighted how vitamin D could regulate several activities and processes.

AIMS

The aim of the present paper was to review and comment on the literature on vitamin D, with a focus on its possible role in the pathophysiology of neuropsychiatric disorders.

DISCUSSION

Available literature indicates that vitamin D regulates a variety of processes in humans and in the central nervous system. Vitamin D deficiency is associated with an enhanced pro-inflammatory state, and formation of Aβ oligomers that might contribute to the cognitive decline typical of the elderly age and, perhaps, dementia. More in general, vitamin D is supposed to play a crucial role in neuroinflammation processes that are currently hypothesized to be involved in the pathophysiology of different psychiatric disorders, such as major depression, bipolar disorders, obsessive-compulsive disorders and psychosis.

CONCLUSION

It is conceivable that vitamin D supplementation might pave the way towards "natural" treatments of a broad range of neuropsychiatric disorders, or at least be useful to boost response to psychotropic drugs in resistant cases.

Anxiety disturbs the blood plasma metabolome in acute coronary syndrome patients

Coronary heart disease (CHD) is the result of a complex metabolic disorder caused by various environmental and genetic factors, and often has anxiety as a comorbidity. Rupture of atherosclerotic plaque in CHD patients can lead to acute coronary syndrome (ACS). Anxiety is a known independent risk factor for the adverse cardiovascular events and mortality in ACS, but it remains unclear how stress-induced anxiety behavior impacts their blood plasma metabolome and contributes to worsening of CHD. The present study aimed to determine the effect of anxiety on the plasma metabolome in ACS patients. After receiving ethical approval 26 ACS patients comorbid anxiety were recruited and matched 26 ACS patients. Blood plasma samples were collected from the patients and stored at − 80 °C until metabolome profiling. Metabolome analysis was performed by liquid chromatography mass spectrometry (LC–MS), and the data were subjected to multivariate analysis. Disturbance of 39 plasma metabolites was noted in the ACS with comorbid anxiety group compared to the ACS group. These disturbed metabolites were mainly involved in tryptophan metabolism, pyrimidine metabolism, glycerophospholipid metabolism, pentose phosphate pathway, and pentose and glucuronate interconversions. The most significantly affected pathway was tryptophan metabolism including the down-regulation of tryptophan and serotonin. Glycerophospholipids metabolism, pentose and glucuronate interconversions, and pentose phosphate pathway were also greatly affected. These results suggest that anxiety can disturb three translation of material in ACS patients. Besides the above metabolism pathways pyrimidine metabolism was significantly disturbed. Based on the present findings the plasma metabolites monitoring can be recommended and may be conducive to early biomarkers detection for personalized treatment anxiety in CHD patients in future.

SLC6A3 as a potential circulating biomarker for gastric cancer detection and progression monitoring

BACKGROUND

Gastric cancer is a malignant tumor originating from the gastric mucosal epithelium, with no obvious symptoms at the early stage. The dopamine transporter gene (SLC6A3) is involved in the metabolism of dopamine and catecholamine and is a potential gene for Parkinson's disease and alcoholism. But the role of SLC6A3 in gastric cancer is still unknown. The aim of our study is to investigate the potential diagnostic value of SLC6A3 on gastric cancer.

METHODS

Quantitative real-time PCR (RT-qPCR) was used to detect the expression of SLC6A3 in clinical samples and cells. A total of 246 samples were enrolled in this study (26 pairs of tissue samples; Serum of 113 patients with gastric cancer, 51 polyps patients and 56 healthy controls). The diagnostic value of SLC6A3 was evaluated by the ROC curve and analyzed the changes of SLC6A3 expression before and after surgery. The prognostic value, interacting proteins and related pathways of SLC6A3 were evaluated by TCGA analysis in UALCAN database (http://ualcan.path.uab.edu/).

RESULTS

The expression level of SLC6A3 in gastric cancer was significantly higher than that in controls. Further, the proportion under the ROC curve (AUC) for SLC6A3, CEA and CA19-9 was 0.818 (95 % confidence interval [CI]: 0.754 to 0.883, P < 0.001), and the expression level of SLC6A3 in the serum of patients with gastric cancer decreased significantly after surgery (P < 0.001). Bioinformatic enrichment analysis of SLC6A3 displayed the relevant metabolic pathways involved in its interacting proteins.

CONCLUSION

SLC6A3 is involved in the occurrence and development of gastric cancer and can be used as a potential diagnostic indicator for gastric cancer.

Beneficial effects of vitamin D on anxiety and depression-like behaviors induced by unpredictable chronic mild stress by suppression of brain oxidative stress and neuroinflammation in rats

The objective of this study was to investigate the protective effects of vitamin D (Vit D) on anxiety and depression-like behaviors induced by unpredictable chronic mild stress and brain tissue oxidative damage criteria and neuroinflammation in rats. The rats were treated as follows: (1) control, (2) UCMS, (3-5) Vit D 100, 1000, and 10,000 iu + UCMS. Rats were subjected to UCMS for a total of 4 weeks. During week 4, they received seven training trials. The brains were then collected to examine inflammation and oxidative stress criteria. Pretreatment with Vit D enhanced performances of the rats in the elevated plus maze (EPM) and open field (OF) and forced swimming test (FST). UCMS also increased MDA and interleukin-6 (IL-6) levels while decreased CAT, SOD, and thiol. Vit D reversed the effects of UCMS. The results of the current research revealed that Vit D improved UCMS-induced anxiety and depression via decreasing brain oxidative stress and inhibiting neuroinflammation.

Short- and Long-Term Effects of Vitamin D Treatment on Bacillus Calmette-Guerin-Induced Depressive-Like Behavior in Mice

PURPOSE

Depression is one of the most common psychological disorders. The nutritional etiology of the depression proposes that vitamin D may play a significant role in the pathogenesis of depression. Further, vitamin D deficiency has been found to aggravate depression in animals. Therefore, vitamin D treatment might be a potential therapeutic aid in depression management. This study aimed to explore the antidepressant effects of vitamin D in a Bacillus Calmette-Guerin (BCG)-induced depression model.

METHODS

Thirty-six mice were randomly assigned to short-term and long-term experimental groups. In each group, mice were randomly subcategorized into three subgroups: 1. control (received vehicle), 2. BCG (received BCG [10⁷ CFU/mouse]), and 3. BCG + vitamin D (received vitamin D [60.000 IU/kg] before BCG [10⁷ CFU/mouse] inoculation). After completion of the two experimental periods (3 days for the short-term group and 2 weeks for the long-term group), the mice underwent three behavioral tests: locomotor activity, the forced swimming test (FST), and the tail suspension test (TST).

RESULTS

Locomotor activity did not significantly differ among the subgroups in either the long-term or short-term groups. In the short-term group, the total immobility time on the FST was decreased in the vitamin D-treated group compared to the BCG group. However, in the TST, no significant difference was found between the vitamin D-treated group and the BCG group. In the long-term group, the immobility time on the FST was decreased in the vitamin D-treated group compared to the BCG group. Similarly, the total immobility time on the TST was also significantly lower in the vitamin D-treated mice than in the BCG-treated mice.

CONCLUSION

Vitamin D is useful in the management of depressive behavior. The potential role of vitamin D in the etiology of depression should be investigated in future work.

Serum 25-hydroxyvitamin D levels and psychological distress symptoms in patients with affective disorders during the COVID-19 pandemic

BACKGROUND

The COVID-19 pandemic has given rise to stress worldwide, especially in vulnerable people like those suffering from mental illness. This study aims to investigate the psychological distress perceived by a cohort of patients with Major Depressive Disorder (MDD) or Bipolar Disorder (BD) after a seven-week period of lockdown measures, and to analyze serum 25-hydroxyvitamin D [25(OH)D] levels as a potential predictor of distress severity.

METHODS

Fifty-nine remitted MDD and fifty-three euthymic BD patients were enrolled. An online dedicated survey was administered to obtain lockdown-related information and to evaluate COVID-19 related distress by using the Kessler 10 Psychological Distress Scale (K10). Patients' medical records were reviewed to collect sociodemographic and clinical data, including serum 25(OH)D levels dosed in the three months preceding the outbreak. A multivariate general linear model was adopted to test the effect of factors of interest on psychological distress.

RESULTS

In our sample (n = 112), 29 subjects (25.9 %) reported no likelihood of psychological distress, whereas 35 (31.2 %) and 48 (42.9 %) displayed mild and moderate-to-severe likelihood of psychological distress, respectively. Low serum 25(OH)D levels (p = 0.005) and MDD diagnosis (p = 0.001) specifically predicted the severity of psychological distress. Living alone during the lockdown, a longer duration of illness, and smoking habits were more frequently detected in subjects with COVID-19 related distress.

CONCLUSIONS

Low serum 25(OH)D levels and MDD diagnosis predicted an increased vulnerability to the stressful impact of the COVID-19 outbreak. Our results suggest that vitamin D may represent a biological factor mediating the psychological response to stress in individuals with affective disorders and provide further insight into tailoring intervention strategies.

Serum vitamin D, vitamin D receptor and binding protein genes polymorphisms in restless legs syndrome

BACKGROUND/OBJECTIVES

Several studies showed lower serum 25-hydroxyvitamin D levels in patients with idiopathic restless legs syndrome (RLS) compared with matched controls, and a single study showed an association between the rs731236 single nucleotide polymorphism (SNP) in the vitamin D receptor (VDR) gene and the risk for RLS. We aimed to study the relationship between the serum 25-hydroxyvitamin D levels and to confirm previous findings related to SNPs in the VDR and the GC vitamin D binding protein (GC) gene, with the risk for RLS in the Spanish Caucasian population.

METHODS

We genotyped 285 idiopathic RLS patients and 325 age and sex-matched controls for VDRrs2228750, VDRrs7975232, VDRrs739837, VDRrs78783628, GCrs7041 and GCrs4588 SNPs using TaqMan assays, and determined serum 25-hydroxyvitamin D levels in 111 idiopathic RLS patients and 167 controls using an ELISA commercial kit.

RESULTS

Serum 25-hydroxyvitamin D levels were significantly higher in RLS patients than in controls but were unrelated with the 7 SNPs studied. None of the 7 SNPs analyzed was associated with the risk for idiopathic RLS or with a positive family history of RLS. However, RLS patients carrying the rs7975232CC genotype or the rs7975232C allele, had a higher frequency of response to GABAergic drugs. Associations between the age at onset and the severity of RLS with SNPs were inconsistent.

CONCLUSIONS

This study shows an association between increased serum concentrations of 25-hydroxyvitamin D and a lack of association between 7 SNPs in the VDR and in the GC genes with RLS in the Spanish Caucasian population.

Vitamin D: Brain and Behavior

It has been 20 years since we first proposed vitamin D as a "possible" neurosteroid.^{( 1 )} Our work over the last two decades, particularly results from our cellular and animal models, has confirmed the numerous ways in which vitamin D differentiates the developing brain. As a result, vitamin D can now confidently take its place among all other steroids known to regulate brain development.^{( 2 )} Others have concentrated on the possible neuroprotective functions of vitamin D in adult brains. Here these data are integrated, and possible mechanisms outlined for the various roles vitamin D appears to play in both developing and mature brains and how such actions shape behavior. There is now also good evidence linking gestational and/or neonatal vitamin D deficiency with an increased risk of neurodevelopmental disorders, such as schizophrenia and autism, and adult vitamin D deficiency with certain degenerative conditions. In this mini-review, the focus is on what we have learned over these past 20 years regarding the genomic and nongenomic actions of vitamin D in shaping brain development, neurophysiology, and behavior in animal models. © 2020 The Author. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Cholecalciferol abolishes depressive-like behavior and hippocampal glucocorticoid receptor impairment induced by chronic corticosterone administration in mice

Several attempts have been made to understand the role of cholecalciferol (vitamin D₃) in the modulation of neuropsychiatric disorders. Notably, the deficiency of vitamin D₃ is considered a pandemic and has been postulated to enhance the risk of major depressive disorder (MDD). Therefore, this study aims to investigate the antidepressant-like effect of cholecalciferol in a mouse model of depression induced by corticosterone, and the possible role of glucocorticoid receptors (GR), NLRP3 and autophagic pathways in this effect. Corticosterone administration (20 mg/kg, p.o., for 21 days) significantly increased the immobility time and grooming latency, as well as reduced the total time spent grooming in mice subjected to the tail suspension test (TST) and splash test (ST), respectively. Importantly, these behavioral alterations were associated with reduced GR immunocontent in the hippocampus of mice. Conversely, the repeated administration of cholecalciferol (2.5 μg/kg, p.o.) in the last 7 days of corticosterone administration was effective to prevent the increased immobility time in the TST and the reduced time spent grooming in the ST, and partially abolished the increase in the grooming latency induced by corticosterone, suggesting its antidepressant-like effect. These behavioral effects were similar to those exerted by fluoxetine (10 mg/kg, p.o.). Moreover, the corticosterone-induced reduction on hippocampal GR immunocontent was not observed in mice treated with cholecalciferol. Additionally, cholecalciferol treatment per se reduced the immunocontent of NLRP3 inflammasome-related proteins ASC, caspase-1, and TXNIP in the hippocampus of mice. No alterations on hippocampal immunocontent of the autophagic-related proteins phospho-mTORC1, beclin-1, and LC3A/B were observed following cholecalciferol treatment and/or corticosterone administration. Collectively, our results provide insights into the effects of cholecalciferol in depression-related behaviors that seem to be related, at least in part, to GR modulation.

Effects of vitamin D and paricalcitol on epileptogenesis and behavioral properties of WAG/Rij rats with absence epilepsy

AIM

Vitamin D (Vit D) has been considered as a neurosteroid and has a pivotal role in neuroprotection including epilepsy. Vit D regulator acts via a Vit D receptor (VDR). WAG/Rij rats have a genetically epileptic model of absence epilepsy with comorbidity of depression. The aim of the present study was to investigate the effect of Vit D and paricalcitol (PRC) on WAG/Rij rats.

MATERIAL AND METHODS

Sixty-three male WAG/Rij rats and seven male Wistar rats were used. The effects of acute and chronic treatment with Vit D (5.000 and 60.000 IU/kg, i.p) and PRC (0.5, 5 and 10 μg/kg, i.p) on absence seizures, and related psychiatric comorbidity were investigated in WAG/Rij rats. Depression-like behavior was assayed by using the forced swimming test (FST) and; anxiety-like behavior by using the open field test (OFT).

RESULTS

Acute Vit D treatments (5.000 and 60.000 IU/kg) similarly reduced the number and duration of spike-wave discharges (SWDs) and showed anxiolytic-antidepressive effect whereas there were no significant changes in other measured parameters between the daily and the bolus dose of Vit D. Acute administration of PRC (0.5, 5 and 10 μg/kg) showed anti-convulsive and anxiolytic-antidepressive effect. The dose (0.5 μg/kg) of PRC was the most effective dose. Chronic treatment was more effective than acute therapy in all parameters.

CONCLUSION

The results of the present study demonstrate that Vit D and PRC have antiepileptic and anxiolytic-antidepressive effects on the absence epilepsy in WAG/Rij rats.

Effects of Vitamin D3 in Long-Term Ovariectomized Rats Subjected to Chronic Unpredictable Mild Stress: BDNF, NT-3, and NT-4 Implications

The purpose of this study was to explore the antidepressant-like effects of vitamin D₃ at different doses (1.0, 2.5, and 5.0 mg/kg sc) on a model of depression produced by chronic unpredictable mild stress (CUMS) for 28 days in long-term (3 months) ovariectomized (OVX) adult rats. Sucrose preference (SPT), forced swimming (FST) and open-field (OFT) tests were conducted to examine the depression-like state. Serum corticosterone/adrenocorticotrophic hormone (ACTH) levels and hippocampal brain-derived neurotrophic factor (BDNF) and neurotrophin (NT)-3/NT-4 expressions by ELISA kits and/or western blotting were determined to assess the possible mechanisms of the vitamin D₃ effects on the depression-like profile in long-term OVX rats subjected to CUMS. The results showed that vitamin D₃ (5.0 mg/kg), as well as fluoxetine treatment, considerably reversed the depression-like state in the SPT and FST, decreased serum corticosterone/ACTH levels, and increased BDNF and NT-3/NT-4 levels in the hippocampus of long-term OVX rats compared to OVX rats with CUMS (p < 0.05). Thus, a high dose of vitamin D₃ (5.0 mg/kg sc) could improve the depression-like profile in long-term OVX adult female rats subjected to the CUMS procedure, which might be mediated by the regulation of BDNF and the NT-3/NT-4 signaling pathways in the hippocampus, as well as the corticosterone/ACTH levels of the blood serum.

Potential Role of Vitamin D for the Management of Depression and Anxiety

Vitamin D, a fat-soluble vitamin, plays a role not only in calcium and phosphate homeostasis but also in several other functions, including cell growth and neuromuscular and immune function. The deficiency of vitamin D is highly prevalent throughout the world and has been suggested to be associated with an enhanced risk of major depressive disorder (MDD) and anxiety disorders. Therefore, vitamin D supplementation has been investigated for the prevention and treatment of these disorders. This review presents preclinical and clinical evidence of the effects of vitamin D supplementation in these disorders. Although preclinical studies provide limited evidence on the possible mechanisms underlying the beneficial effects of vitamin D for the management of these disorders, most of the clinical studies have indicated that vitamin D supplementation is associated with the reduction of symptoms of depression and anxiety, particularly when the supplementation was carried out in individuals with an MDD diagnosis (of the 13 studies in which MDD diagnosis was established, 12 had positive results with vitamin supplementation). However, some heterogeneity in the outcomes was observed and might be associated with an absence of overt psychiatric symptoms in several studies, genetic polymorphisms that alter vitamin D metabolism and bioavailability, differences in the supplementation regimen (monotherapy, adjunctive therapy, or large bolus dosing), and levels of 25-hydroxyvitamin D₃ (25(OH)D) at baseline (individuals with low vitamin D status may respond better) and attained after supplementation. Additionally, factors such as sex, age, and symptom severity also need to be further explored in relation to the effects of vitamin D. Therefore, although vitamin D may hold significant potential for mental health, further preclinical and clinical studies are clearly necessary to better understand its role on mood/affect modulation.