Effects of cholecalciferol on behavior and production of reactive oxygen species in female mice subjected to corticosterone-induced model of depression

Combination of vitamin D3 and fructooligosaccharides upregulates colonic vitamin D receptor in C57BL/6J mice and affects anxiety-related behavior in a sex-specific manner

Depression and anxiety disorders are among the most common mental health disorders that affect US adults today, frequently related to vitamin D (VD) insufficiency. Along with VD, growing evidence suggests gut microbiota likely play a role in neuropsychiatric disorders. Here, we investigated if modulation of gut microbiota would disrupt host VD status and promote behaviors related to depression and anxiety in adult mice. Six-week-old male and female C57BL/6J mice (n = 10/mice/group) were randomly assigned to receive (1) control diet (CTR), control diet treated with antibiotics (AB), control diet with total 5000 IU of VD (VD), VD treated with antibiotics (VD + AB), VD supplemented with 5% w/w fructooligosaccharides (FOS; VF), and VF diet treated with antibiotics (VF + AB), respectively, for 8 weeks. Our study demonstrated that VD status was not affected by antibiotic regimen. VD alone ameliorates anxiety-related behavior in female mice, and that combination with FOS (i.e., VF) did not further improve the outcome. Male mice, in contrast, exhibit greater anxiety with VF, but not VD, when compared with CTR mice. Colonic VD receptor was elevated in VF-treated mice in both sexes, compared with CTR, which was positively correlated to colonic TPH1, a rate-limiting enzyme for serotonin synthesis. Taken together, our data indicate that the effect of VF on anxiety-related behavior is sex-specific, which may partially be attributed to the activation of colonic VD signaling and subsequent serotonin synthesis. The synergistic or additive effect of VD and FOS on mood disorders remained to be investigated.

The role of vitamin D in depression and anxiety disorders: a review of the literature

BACKGROUND

Prevalence of mental health disorders continue to increase worldwide. Over the past decades, suboptimal vitamin D (VD) levels and gut dysbiosis have been associated with neurological dysfunction and psychiatric disorders.

METHODS

In this review, we examined the available literature on VD and mental health disorders, particularly depression and anxiety, in both clinical and pre-clinical studies.

RESULTS

Our extensive review failed to find a link between VD deficiency, depression, and anxiety-related behavior in preclinical animal models. However, strong evidence suggests that VD supplementation may alleviate symptoms in chronically stressed rodents, with some promising evidence from clinical studies. Further, fecal microbiota transplantations suggest a potential role of gut microbiota in neuropsychiatric disorders, although the underlying mechanisms remain to be fully elucidated. It has been postulated that serotonin, primarily produced by gut bacteria, may be a crucial factor. Hence, whether VD has the ability to impact gut microbiota and modulate serotonin synthesis warrants further investigation.

CONCLUSIONS

Taken together, literature has suggested that VD may serve as a key regulator in the gut-brain axis to modulate gut microbiota and alleviate symptoms of depression and anxiety. The inconsistent results of VD supplementation in clinical studies, particularly among VD deficient participants, suggests that current intake recommendations may need to be re-evaluated for individuals at-risk (i.e. prior to diagnosis) of developing depression and/or anxiety.

Role of Inflammatory Mechanisms in Major Depressive Disorder: From Etiology to Potential Pharmacological Targets

The involvement of central and peripheral inflammation in the pathogenesis and prognosis of major depressive disorder (MDD) has been demonstrated. The increase of pro-inflammatory cytokines (interleukin (IL)-1β, IL-6, IL-18, and TNF-α) in individuals with depression may elicit neuroinflammatory processes and peripheral inflammation, mechanisms that, in turn, can contribute to gut microbiota dysbiosis. Together, neuroinflammation and gut dysbiosis induce alterations in tryptophan metabolism, culminating in decreased serotonin synthesis, impairments in neuroplasticity-related mechanisms, and glutamate-mediated excitotoxicity. This review aims to highlight the inflammatory mechanisms (neuroinflammation, peripheral inflammation, and gut dysbiosis) involved in the pathophysiology of MDD and to explore novel anti-inflammatory therapeutic approaches for this psychiatric disturbance. Several lines of evidence have indicated that in addition to antidepressants, physical exercise, probiotics, and nutraceuticals (agmatine, ascorbic acid, and vitamin D) possess anti-inflammatory effects that may contribute to their antidepressant properties. Further studies are necessary to explore the therapeutic benefits of these alternative therapies for MDD.

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.

The Role of Adipokines in Health and Disease

Adipokines are cell-signaling proteins secreted by adipose tissue that has been related to a low-grade state of inflammation and different pathologies. The present review aims to analyze the role of adipokines in health and disease in order to understand the important functions and effects of these cytokines. For this aim, the present review delves into the type of adipocytes and the cytokines produced, as well as their functions; the relations of adipokines in inflammation and different diseases such as cardiovascular, atherosclerosis, mental diseases, metabolic disorders, cancer, and eating behaviors; and finally, the role of microbiota, nutrition, and physical activity in adipokines is discussed. This information would allow for a better understanding of these important cytokines and their effects on body organisms.

The antidepressant-like effect elicited by vitamin D3 is associated with BDNF/TrkB-related synaptic protein synthesis

Vitamin D₃ (cholecalciferol) has been shown to exert antidepressant-like responses, but the role BDNF/TrkB-related synaptic plasticity in this effect remains to be established. Thus, this study investigated the time-course antidepressant-like response of vitamin D₃ in female and male mice and the possible role of BDNF/TrkB signaling in this response. The repeated (7 and 21 days), but not acute (60 min), administration of vitamin D₃ (2.5 μg/kg, p.o.) exerted an antidepressant-like effect in female and male mice subjected to the tail suspension test, without altering the basal locomotor activity in the open-field test. Notably, vitamin D₃ caused a similar time-dependent antidepressant-like effect in male and female mice, suggesting that this behavioral response in the tail suspension test might not be affected by sex differences. Vitamin D₃ administration for 21 days, but not for 7 days or 1 h, augmented BDNF levels in the hippocampus and prefrontal cortex of mice. No effects on phospho-CREB/CREB levels were detected in the hippocampus and prefrontal cortex after chronic vitamin D₃ administration. Additionally, vitamin D₃ increased TrkB, GluA1, and PSD-95 levels in the prefrontal cortex, but not in the hippocampus. Furthermore, an upregulation of synapsin level was observed in both brain regions after vitamin D₃ administration. These findings reinforce and extend the notion that vitamin D₃ is effective to produce antidepressant-like responses in male and female mice and provide novel evidence that this effect could be associated with BDNF/TrkB-related synaptic protein synthesis. Finally, vitamin D₃ could be a feasible nutritional strategy for the management of depression.

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.

Molecular Basis Underlying the Therapeutic Potential of Vitamin D for the Treatment of Depression and Anxiety

Major depressive disorder and anxiety disorders are common and disabling conditions that affect millions of people worldwide. Despite being different disorders, symptoms of depression and anxiety frequently overlap in individuals, making them difficult to diagnose and treat adequately. Therefore, compounds capable of exerting beneficial effects against both disorders are of special interest. Noteworthily, vitamin D deficiency has been associated with an increased risk of developing depression and anxiety, and individuals with these psychiatric conditions have low serum levels of this vitamin. Indeed, in the last few years, vitamin D has gained attention for its many functions that go beyond its effects on calcium–phosphorus metabolism. Particularly, antioxidant, anti-inflammatory, pro-neurogenic, and neuromodulatory properties seem to contribute to its antidepressant and anxiolytic effects. Therefore, in this review, we highlight the main mechanisms that may underlie the potential antidepressant and anxiolytic effects of vitamin D. In addition, we discuss preclinical and clinical studies that support the therapeutic potential of this vitamin for the management of these disorders.

Involvement of serotonergic neurotransmission in the antidepressant-like effect elicited by cholecalciferol in the chronic unpredictable stress model in mice

Cholecalciferol deficiency has been associated with stress-related psychiatric disorders, particularly depression. Therefore, the present study investigated the antidepressant-like effect of cholecalciferol in female mice and the possible role of the serotonergic system in this response. The ability of cholecalciferol to elicit an antidepressant-like effect and to modulate serotonin levels in the hippocampus and prefrontal cortex of mice subjected to chronic unpredictable stress (CUS) was also investigated. The administration of cholecalciferol (2.5, 7.5, and 25 µg/kg, p.o.) for 7 days, similar to fluoxetine (10 mg/kg, p.o., serotonin reuptake inhibitor), reduced the immobility time in the tail suspension test, without altering the locomotor performance in the open-field test. Moreover, the administration of p-chlorophenylalanine methyl ester (PCPA - 100 mg/kg, i.p., for 4 days, a selective inhibitor of tryptophan hydroxylase, involved in the serotonin synthesis) abolished the antidepressant-like effect of cholecalciferol and fluoxetine in the tail suspension test, demonstrating the involvement of serotonergic system. Additionally, CUS protocol (21 days) induced depressive-like behavior in the tail suspension test and decreased serotonin levels in the prefrontal cortex and hippocampus of mice. Conversely, the administration of cholecalciferol and fluoxetine in the last 7 days of CUS protocol completely abolished the stress-induced depressive-like phenotype. Cholecalciferol was also effective to abrogate CUS-induced reduction on serotonin levels in the prefrontal cortex, but not in the hippocampus. Our results indicate that cholecalciferol has an antidepressant-like effect in mice by modulating the serotonergic system and support the assumption that cholecalciferol may have beneficial effects for the management of depression.

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.

Traditional Chinese Formula Xiaoyaosan Alleviates Depressive-Like Behavior in CUMS Mice by Regulating PEBP1-GPX4-Mediated Ferroptosis in the Hippocampus

BACKGROUND

At present, the pathogenesis of depression is not fully understood, and nearly half of depression patients experience no obvious effects during treatment. This study aimed to establish a depression mouse model to explore the possible role of ferroptosis in the pathogenesis of depression, and observe the effects of Xiaoyaosan on PEBP1-GPX4-mediated ferroptosis in the hippocampus.

METHODS

Forty-eight male C57BL/6 mice were randomly divided into a control group, CUMS group, Xiaoyaosan group and fluoxetine group, and the model was established by chronic unpredictable mild stress (CUMS) for a successive 6 weeks. The medication procedure was performed from the 4th to the 6th week of modeling. The behavioral evaluations were measured to evaluate depressive-like behaviors. The expressions of GPX4, FTH1, ACSL4 and COX2 were detected as ferroptosis-related indicators. Then, the total iron and ferrous content in the hippocampus were measured. The levels of PEBP1 and ERK1/2 were observed, and the expressions of GFAP and IBA1 were also detected to measure the functions of astrocytes and microglia in the hippocampus.

RESULTS

Eight herbs of Xiaoyaosan had 133 active ingredients which could regulate the 43 ferroptosis-related genes in depression. After 6 weeks of modeling, the data showed that mice in the CUMS group had obvious depressive-like behaviors, and medication with Xiaoyaosan or fluoxetine could significantly improve the behavioral changes. The expressions of GPX4, FTH1, ACSL4, COX2, PEBP1, ERK1/2, GFAP and IBA1 changed in the CUMS group mice, while the total iron and ferrous content also changed. Xiaoyaosan and fluoxetine had obvious curative effects that could significantly alleviate the above changes in the hippocampus.

CONCLUSION

Our results revealed that the activation of ferroptosis might exist in the hippocampi of CUMS-induced mice. The PEBP1-GPX4-mediated ferroptosis could be involved in the antidepressant mechanism of Xiaoyaosan. It also implied that ferroptosis could become a new target for research into the depression mechanism and antidepressant drugs.

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.

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.