The antidepressant-like action of a simple selenium-containing molecule, methyl phenyl selenide, in mice

Electroacupuncture Alleviates Neuropathic Pain and Negative Emotion in Mice by Regulating Gut Microbiota

Background

Neuropathic pain (NP) is a prevalent chronic condition frequently accompanied by adverse emotional states. Previous research has demonstrated the clinical efficacy of electroacupuncture (EA) in mitigating neuropathic pain and its associated mood disorders. Recent studies have underscored a correlation between gut microbiota and both NP and negative emotional states. Nevertheless, the relationship between the modulation of gut microbiota by EA and the amelioration of NP remains inadequately understood.

Methods

Mice were randomly assigned to one of the three groups: the Control (Con) group, the EA group, and the Chronic Constrictive Injury (CCI) group (n = 12 each). Starting from the 8th day post-CCI induction, the EA group underwent EA treatment once every two days, for a total of 20 sessions. To investigate the impact of gut microbiota on CCI mice, we employed a variety of methods, including various behavioral tests and 16S ribosomal DNA (rDNA) sequencing.

Results

The results indicated that EA significantly ameliorated mechanical allodynia and emotional dysfunction induced by CCI in mice. Analysis through 16S rDNA sequencing revealed that the gut microbiota of NP model mice exhibited a marked increase in diversity. However, EA could partially reverse changes in the diversity of gut microbiota. The abundance of Alloprevotella, A2, Roseburia, Muribaculum, Ruminiclostridium, and Rikenella was increased, and the abundance levels of Bacteroides were decreased at the genus level in CCI mice. Following EA treatment, the relative abundance of Alistipes, A2, Roseburia, and Rikenella was decreased, whereas the relative abundance of Alloprevotella and Parabacteroides was increased in EA group when compared with the CCI group.

Conclusion

These findings suggested that EA exerted a significant therapeutic effect on NP, potentially through modulation of the gut microbiota.

Effects of Selen on the Antidepressant-like Activity of Agents Affecting the Adenosinergic Neurotransmission

The main goal of this study was to determine the antidepressant-like potential of the co-administration of sodium selenite (Se) and the selective adenosine A1 and A2A antagonists DPCPX and istradefylline (IST), respectively, in mice despair tests. Biochemical studies were performed to elucidate the action mechanisms of the investigated treatment strategies. The results confirmed that, when administered by itself, Se exerts an antidepressant-like effect in the FST and TST and that this activity is dose-dependent. Further experiments demonstrated that Se (0.25 mg/kg) significantly enhanced the activity of mice in both tests when co-administered with DPCPX (1 mg/kg) and IST (0.5 mg/kg) at doses which would be ineffective if administered individually. Our research revealed that neither DPCPX, IST, nor Se or combinations of the tested substances induced significant changes in the brain-derived neurotrophic factor (BDNF) levels in mice serum vs. the NaCl-treated group. However, we observed a decrease in the mRNA level of antioxidant defense enzymes. Molecular studies also showed changes in the expression of the Slc6a15, Comt, and Adora1 genes, particularly after exposure to the combination of Se and DPCPX, which indicates a beneficial effect and may help to explain the key mechanism of the antidepressant effect. The combination of Se with substances attenuating adenosine neurotransmission may become a new therapeutic strategy for patients with depression.

D-galactose induced dysfunction in mice hippocampus and the possible antioxidant and neuromodulatory effects of selenium

Aging is an ultimate reality that everyone has to face. D-galactose (D-gal) has been used extensively to develop aging model. Trace elements such as selenium (Se) have been used as a potential antioxidant for neuro-protection. The present work aims to develop therapeutic agents such as Se for the treatment of aging-induced neurological ailments such as anxiety, depression, and memory impairment. For this purpose, mice were treated with D-gal at a dose of 300 mg/ml/kg and various doses of Se (0.175 and 0.35mg/ml/kg) for 28 days. Behavioral tests were monitored after treatment days. After the behavioral assessment, mice were decapitated and their brains were collected. Hippocampi were removed from the brain for biochemical, neurochemical, and histopathological analysis. The present findings of behavioral analysis showed that D-gal-induced anxiety- and depression-like symptoms were inhibited by both doses of Se. D-gal-induced memory alteration was also prevented by repeated doses of Se (0.175 and 0.35mg/ml/kg). Biochemical analysis showed that D-gal-induced increase of oxidative stress and inflammatory markers and decrease of antioxidant enzymes and total protein contents in the hippocampus were prevented by Se administration. An increase in the activity of acetylcholinesterase was also diminished by Se. The neurochemical assessment showed that D-gal-induced increased serotonin metabolism and decreased acetylcholine levels in the hippocampus were restored by repeated treatment of Se. Histopathological estimations also exhibited; normalization of D-gal induced neurodegenerative changes. It is concluded that D-gal-induced dysfunction in mice hippocampus caused anxiety, depression, memory impairment, oxidative stress, neuro-inflammation, and histological alterations that were mitigated by Se via its antioxidant potential, anti-inflammatory property, and modulating capability of serotonergic and cholinergic functions.

Toxicology and pharmacology of synthetic organoselenium compounds: an update

Here, we addressed the pharmacology and toxicology of synthetic organoselenium compounds and some naturally occurring organoselenium amino acids. The use of selenium as a tool in organic synthesis and as a pharmacological agent goes back to the middle of the nineteenth and the beginning of the twentieth centuries. The rediscovery of ebselen and its investigation in clinical trials have motivated the search for new organoselenium molecules with pharmacological properties. Although ebselen and diselenides have some overlapping pharmacological properties, their molecular targets are not identical. However, they have similar anti-inflammatory and antioxidant activities, possibly, via activation of transcription factors, regulating the expression of antioxidant genes. In short, our knowledge about the pharmacological properties of simple organoselenium compounds is still elusive. However, contrary to our early expectations that they could imitate selenoproteins, organoselenium compounds seem to have non-specific modulatory activation of antioxidant pathways and specific inhibitory effects in some thiol-containing proteins. The thiol-oxidizing properties of organoselenium compounds are considered the molecular basis of their chronic toxicity; however, the acute use of organoselenium compounds as inhibitors of specific thiol-containing enzymes can be of therapeutic significance. In summary, the outcomes of the clinical trials of ebselen as a mimetic of lithium or as an inhibitor of SARS-CoV-2 proteases will be important to the field of organoselenium synthesis. The development of computational techniques that could predict rational modifications in the structure of organoselenium compounds to increase their specificity is required to construct a library of thiol-modifying agents with selectivity toward specific target proteins.

Diorganyl Dichalcogenides and Copper/Iron Salts: Versatile Cyclization System To Achieve Carbo- and Heterocycles from Alkynes

Organochalcogen-containing cyclic molecules have shown several promising pharmacological properties. Consequently, different strategies have been developed for their synthesis in the past few years. Particularly due to the low cost and environmental aspects, copper- and iron-promoted cyclization reactions of alkynyl substrates have been broadly and efficiently applied for this purpose. This short review presents an overview of the most recent advances in the synthesis of organochalcogen-containing carbo- and heterocycles by reacting diorganyl disulfides, diselenides, and ditellurides with alkyne derivatives in the presence of copper and iron salts to promote cyclization reactions.

1 Introduction

2 Synthesis of Carbo- and Heterocycles via Reactions of Alkynes with Diorganyl Dichalcogenides and Copper Salts

3 Synthesis of Carbo- and Heterocycles via Reactions of Alkynes with Diorganyl Dichalcogenides and Iron Salts

4 Conclusions

Metabolic Framework for the Improvement of Autism Spectrum Disorders by a Modified Ketogenic Diet: A Pilot Study

The ketogenic diet (KD) can improve the core features of autism spectrum disorders (ASD) in some children, but the effects on the overall metabolism remain unclear. This pilot study investigated the behavioral parameters in relation to blood metabolites and trace elements in a cohort of 10 typically developed controls (TC) and 17 children with ASD at baseline and following 3 months of treatment with a modified KD regimen. A nontargeted, multiplatform metabolomic approach was employed, including gas chromatography-mass spectrometry, ¹H nuclear magnetic resonance spectroscopy, and inductively coupled plasma-mass spectrometry. The associations among plasma metabolites, trace elements, and behavior scores were investigated. Employing a combination of metabolomic platforms, 118 named metabolites and 73 trace elements were assessed. Relative to TC, a combination of glutamate, galactonate, and glycerol discriminated ASD with 88% accuracy. ASD had higher concentrations of galactose intermediates, gut microbe-derived trimethylamine N-oxide and N-acetylserotonin, and lower concentrations of 3-hydroxybutyrate and selenium at baseline. Following 3 months of KD intervention, the levels of circulating ketones and acetylcarnitine were increased. KD restored lower selenium levels in ASD to that of controls, and correlation analysis identified a novel negative correlation between the changes in selenium and behavior scores. Based on the different behavior responses to KD, we found that high responders had greater concentrations of 3-hydroxybutyrate and ornithine, with lower galactose. These findings enhance our current understanding of the metabolic derangements present in ASD and may be of utility in predicting favorable responses to KD intervention.

Synthesis and computer-aided SAR studies for derivatives of phenoxyalkyl-1,3,5-triazine as the new potent ligands for serotonin receptors 5-HT6

This research has provided the most active 5-HT₆R agents among 1,3,5-triazine derivatives investigated to date and has also identified the world's first selenium-containing 5-HT₆R ligands. The studies are focused on design, synthesis, biological evaluation and docking-supported SAR analysis for novel 5-HT₆R agents as derivatives of lead structure 4-(4-methylpiperazin-1-yl)-6-(phenoxymethyl)-1,3,5-triazin-2-amine (7). The lead modifications included an introduction of: (i) various small substituents at benzene ring, (ii) a branched ether linker or (iii) the ether oxygen replacement with other chalcogen (S, Se) or sulfonyl moiety. Hence, a series of new compounds (7-24) was synthesized and examined on their affinities for 5-HT₆R and selectivity, in respect to the 5-HT_1AR, 5-HT_2AR, 5-HT₇R and dopamine D₂ receptor, in the radioligand binding assays. For representative most active compounds functional bioassays and toxicity profile in vitro and antidepressant-like activity in vivo were examined. The 2-isopropyl-5-methylphenyl derivative (10) was found as the most active triazine 5-HT₆R antagonist (K_i = 11 nM). SAR analysis indicated, that an exchange of oxygen to selenium (7 vs. 22), and especially, to sulfur (7 vs. 19) was beneficial to increase both affinity and antagonistic action for 5-HT₆R. Surprisingly, an introduction of SO₂ caused a drastic decrease of the 5-HT₆R affinity, which was explained at a molecular level based on docking studies. All in vivo tested compounds (10, 18 and 21) did not show any risk of toxicity in the safety studies in vitro.

Synergistic Action of Sodium Selenite with some Antidepressants and Diazepam in Mice

BACKGROUND

The antidepressant and anxiolytic effects of selenium (Se) have been proven in many studies. This work was aimed at confirming these activities of its inorganic form-sodium selenite-and examining the possible synergy of action with antidepressants and diazepam.

METHODS

The antidepressant- and anxiolytic-like activity of Se was assessed using forced swim tests (FSTs) and elevated plus-maze test (EPMs). Spontaneous locomotor activity was measured using photoresistor actimeters. The experiments were conducted on male Albino Swiss mice.

RESULTS

Sodium selenite (0.5 mg/kg) reduced the immobility time in the FSTs and extended time spent in the open arms of EPMs without affecting locomotor activity The combined administration of Se at an ineffective dose (0.25 mg/kg) together with imipramine (15 mg/kg), fluoxetine (5 mg/kg), tianeptine (10 mg/kg), but not with reboxetine (2.5 mg/kg), resulted in a reduction of immobility time in FSTs, and with a threshold dose of diazepam (0.25 mg/kg) led to the prolongation of time spent in the open arms of the EPM. Moreover, the antidepressant-like effect of Se (0.5 mg/kg) was significantly reduced by pretreatment with p-chlorophenylalanine (100 mg/kg).

CONCLUSIONS

The results may indicate the participation of serotonergic transmission to antidepressant action of Se and GABA-ergic transmission to its anxiolytic effects.

Therapeutic applications of selenium-derived compounds

Selenium is a biocompatible element and participates in several biochemical reactions occurring in the human body. Its biocompatibility and minimal toxicity has attracted researchers to develop selenium-based drugs. Hence, recent developments on biomedical applications of selenium-based compounds have been discussed. A structure activity relationship has also been interpreted.

Dopaminergic dysregulation and impaired associative learning behavior in zebrafish during chronic dietary exposure to selenium

A growing body of evidence indicates that exposure to selenium (Se) can cause neurotoxicity, and this can occur because of its interference with several neurotransmitter systems in humans and animals. Dopamine is a critical modulator of a variety of brain functions and a prime target for environmental neurotoxicants. However, effects of environmentally relevant concentrations of Se on dopaminergic system and its neurobehavioral effects are still largely unknown. For this purpose, we exposed zebrafish, a model organism, to different concentrations of dietary l-selenomethionine (control, 3.5, 11.1, 27.4, and 63.4 μg Se/g dry weight) for a period of 60 days. Cognitive performance of fish was evaluated using a plus maze associative learning paradigm. Oxidative stress, as the main driver of Se neurotoxicity, was assessed by measuring the ratio of reduced to oxidized glutathione (GSH:GSSG), lipid peroxidation (LPO) levels, and mRNA expression of several antioxidant enzymes in the zebrafish brain. Dopamine levels in the brain and the expression of genes involved in dopamine synthesis, storage, reuptake, metabolism, and receptor activation were examined. Moreover, transcription of several synaptic plasticity-related immediate-early and late response genes was determined. Overall, fish fed with the two highest concentrations of dietary Se displayed impaired associative learning. Se exposure also induced oxidative stress in the zebrafish brain, as indicated by a reduction in GSH:GSSG ratio, increased LPO levels, and up-regulation of antioxidant genes in fish treated with the two highest concentrations of Se. An increase in brain dopamine levels associated with altered expression of dopaminergic cell markers was evident in different treatment groups. Moreover, Se exposure led to the down-regulation of immediate-early and late response genes in fish that exhibiting learning impairment. Taken together, the results of this study imply that the induction of oxidative stress and dysregulation of dopaminergic neurotransmission may underlie Se-induced impairment of associative learning in zebrafish.

Chronic Dietary Selenomethionine Exposure Induces Oxidative Stress, Dopaminergic Dysfunction, and Cognitive Impairment in Adult Zebrafish (Danio rerio)

The present study was designed to investigate the effects of chronic dietary exposure to selenium (Se) on zebrafish cognition and also to elucidate possible mechanism(s) by which Se exerts its neurotoxicity. To this end, adult zebrafish were exposed to different concentrations of dietary l-selenomethionine (control, 2.3, 9.7, 32.5, or 57.7 μg Se/g dry weight) for 30 days. Cognitive performance of fish was tested using a latent learning paradigm in a complex maze. In addition, we also evaluated oxidative stress biomarkers and the expression of genes involved in dopaminergic neurotransmission in the zebrafish brain. Fish treated with higher dietary Se doses (32.5 and 57.5 μg Se/g) exhibited impaired performance in the latent learning task. The impaired learning was associated with the induction of oxidative stress and altered mRNA expression of dopamine receptors, tyrosine hydroxylase, and dopamine transporter genes in the zebrafish brain. Collectively, our results illustrate that cognitive impairment in zebrafish could be associated with Se-induced oxidative stress and altered dopaminergic neurotransmission in the brain.

Selenium and manganese in depression – preclinical and clinical studies

According to the World Health Organization estimates, approximately 10% of the world’s population is affected by depressive disorders. Furthermore, even in high-income countries, many people with depression are not treated, which can lead to serious health consequences and a global economic loss. Unfortunately, the current pharmacotherapy of depressive disorders is characterized by unsatisfactory efficacy and the therapeutic effect is accompanied by many side effects. For this reason, there is still ongoing worldwide research to find new antidepressant therapies. In recent years, many data have been shown that essential elements demonstrate the antidepressant action and increase the effect of antidepressants. In this paper we present the results from the preclinical and clinical studies published over the years which show the involvement of selenium and manganese in depressive disorders. In this article, the relationship between the amount of these microelements in a diet and depression is reviewed and what's more, the association among these elements in different biomaterial and their relations to depressive symptoms is presented. Additionally, we discuss the possible influence of selenium and manganese on modulating neurotransmitter system involved in depression.

Antidepressant and anxiolytic-like activity of sodium selenite after acute treatment in mice

BACKGROUND

Selenium (Se) is an essential trace element for humans and animals, that is needed for a broad variety of physiological functions including thyroid hormone metabolism, protection against oxidative stress, and immunity associated functions. Human nutritional Se deficiencies are associated with neuropsychiatric diseases, like Alzheimer's disease, Parkinson's disease, obsessive - compulsive disorder, stroke, epilepsy as well as depressive behaviours. In this study we examined antidepressant- and anxiolytic-like activity of Se in the inorganic form of sodium selenite and investigated whether Se influence on the locomotor activity in mice.

METHODS

The antidepressant-like and anxiolytic-like activity of Se was assessed using forced swim test (FST) and elevated plus-maze test (EPM), respectively. Spontaneous locomotor activity was measured using photoresistor actimeters.

RESULTS

Sodium selenite administered at the doses of 0.5, 1, and 2mg/kg, ip reduced immobility time in the FST exerting antidepressant-like activity. In the EPM test, sodium selenite at the same doses, produced anxiolytic-like effect; the doses active in both tests did not affect locomotor activity, indicating that these effects of Se are specific.

CONCLUSIONS

These potential antidepressant- and anxiolytic-like effects of Se require more detailed experimental study using animal models to approach a clear conclusion regarding the potential mechanism of the observed effect.

Sodium selenite supplementation during pregnancy and lactation promotes anxiolysis and improves mnemonic performance in wistar rats' offspring

Selenium is a micronutrient which is part of selenoprotein molecules and participates in a vast number of physiological roles and, among them,we have fetal and neonatal development. Therefore, the aimof this studywas to evaluate possible behavioral changes in offspring of female rats supplemented during pregnancy and lactation with sodium selenite. To address that, we treated two groups of female rats by saline or sodium selenite at a dose of 1mg/kg through oral route and performed neurochemical and behavioral tests. In the offspring, the thyroid profile and hippocampal neurochemistrywere evaluated. Behavioral testswere performed in pups both during childhood and adulthood. We found out that selenium (Se) supplementation increased serum levels of triiodothyronine (25%, p b 0.001) and thyroxine (18%, p b 0.05) and promoted a tryptophan hydroxylase 2 (TPH 2) expression decrease (17%, p b 0.01) and tyrosine hydroxylase (TH) expression increase (202%, p b 0.01) in the hippocampus. The cholinesterase activity was decreased (28%, p b 0.01) in Se supplemented rats, suggesting a neurochemical modulation in the hippocampal activity. During childhood, the Sesupplemented offspring had a reduction in anxiety-like behavior both in elevated plus maze test and in light–dark box test. In adulthood, Se-treated pups had an increase in the locomotor activity (36%, p b 0.05) and in rearing episodes (77%, p b 0.001) in the open field test, while in the elevated plus maze test they also exhibited an increase in the time spent in the open arms (243%, p b 0.01). For the object recognition test, Se-treated offspring showed increase in the absolute (230.16%, p b 0.05) and relative index discrimination (234%, p b 0.05). These results demonstrate that maternal supplementation by sodium selenite promoted psychobiological changes both during childhood and adulthood. Therefore, the behavioral profile observed possibly can be explained by neurochemical changes induced by thyroid hormones during the critical period of the central nervous system ontogeny.

Essential elements in depression and anxiety. Part II

In this paper we continue to discuss the involvement of essential elements in depression and anxiety, and the possible mechanisms that link elements to the neurobiology underlying depression/anxiety. The present paper is focused on copper, selenium, manganese, iodine and vanadium. Different aspects of relationship between elements and depression or anxiety are reviewed, e.g. the association of the amount of an element in a diet or the serum level of an element and depressive or anxiety-like symptoms. Moreover, the relation of selected elements to the pathophysiology of depression or anxiety is discussed in the context of enzymes which require these elements as co-factors and are involved in the underlying pathophysiology of these disorders.

Nutritional strategies for dealing with depression

Depression is a highly recurrent and debilitating psychiatric disorder associated with multicausal origins. Impairments in the monoaminergic transmission, increased glutamatergic excitotoxicity, neuroinflammation, oxidative stress and deficits in neurotrophic factors are the main hypothesis raised in order to explain the etiological basis of depression. Although the current antidepressant therapy usually alleviates symptoms and prevents recurrence of episodes, the delay in the onset of the therapeutic effect and the refractory or intolerant responses exhibited by a large number of patients are the main drawbacks of the current therapy. For these reasons, several studies have dealt with the investigation of alternative therapeutic approaches or adjunctive strategies which could improve clinical outcomes. One potential adjunctive treatment with conventional antidepressants involves the use of nutraceuticals (a food, a part of a food, a vitamin, a mineral, or a herb that provides health benefits). In this review, we will focus on the main nutrients, phytochemicals and food that have been shown to have beneficial effects against depression.