m-Trifluoromethyl-diphenyl diselenide promotes resilience to social avoidance induced by social defeat stress in mice: Contribution of opioid receptors and MAPKs

Regulation of Cortico-Thalamic JNK1/2 and ERK1/2 MAPKs and Apoptosis-Related Signaling Pathways in PDYN Gene-Deficient Mice Following Acute and Chronic Mild Stress

The crosstalk between the opioidergic system and mitogen-activated protein kinases (MAPKs) has a critical role in mediating stress-induced behaviors related to the pathophysiology of anxiety. The present study evaluated the basal status and stress-induced alterations of cortico-thalamic MAPKs and other cell fate-related signaling pathways potentially underlying the anxiogenic endophenotype of PDYN gene-deficient mice. Compared to littermates, PDYN knockout (KO) mice had lower cortical and or thalamic amounts of the phospho-activated MAPKs c-Jun N-terminal kinase (JNK1/2) and extracellular signal-regulated kinase (ERK1/2). Similarly, PDYN-KO animals displayed reduced cortico-thalamic densities of total and phosphorylated (at Ser191) species of the cell fate regulator Fas-associated protein with death domain (FADD) without alterations in the Fas receptor. Exposure to acute restraint and chronic mild stress stimuli induced the robust stimulation of JNK1/2 and ERK1/2 MAPKs, FADD, and Akt-mTOR pathways, without apparent increases in apoptotic rates. Interestingly, PDYN deficiency prevented stress-induced JNK1/2 and FADD but not ERK1/2 or Akt-mTOR hyperactivations. These findings suggest that cortico-thalamic MAPK- and FADD-dependent neuroplasticity might be altered in PDYN-KO mice. In addition, the results also indicate that the PDYN gene (and hence dynorphin release) may be required to stimulate JNK1/2 and FADD (but not ERK1/2 or Akt/mTOR) pathways under environmental stress conditions.

Contribution of Opioid and Nitrergic Systems to m-Trifluoromethyl diphenyl Diselenide Attenuates Morphine-Induced Tolerance in Mice

m-Trifluoromethyl diphenyl diselenide (TFDD) has antinociceptive and antidepressant-like properties and attenuates morphine withdrawal signs in mice. This study investigated if TFDD affects the development of morphine tolerance to its antinociceptive and antidepressant-like effects in mice. We also investigated whether TFDD modulates signaling pathways related to morphine tolerance, including the opioid receptors and some parameters of the nitrergic system. Male adult Swiss mice received morphine alone (5 mg/kg, subcutaneous) and in combination with TFDD (10 mg/kg, intragastric) for 7 days. Mice were subjected to hot plate and forced swim tests on days 1, 3, 5, and 7 of the experimental protocol. Repeated TFDD administrations avoided tolerance development mediated by morphine, including its antinociceptive and antidepressant-like effects. A single morphine dose increased MOR and NOx but decreased iNOS contents in the mouse cerebral cortex. In turn, single morphine and TFDD co-administration restored the MOR and iNOS protein levels. On the other hand, morphine repeated doses enhanced DOR and reduced MOR and NOx contents, whereas the morphine and TFDD association reestablished DOR and NOx levels in the mouse cerebral cortex. In conclusion, some opioid and nitrergic system parameters might contribute to TFDD attenuation of antinociceptive and antidepressant-like tolerance induced by morphine in mice.

Resilience to the effects of social stress on vulnerability to developing drug addiction

We review the still scarce but growing literature on resilience to the effects of social stress on the rewarding properties of drugs of abuse. We define the concept of resilience and how it is applied to the field of drug addiction research. We also describe the internal and external protective factors associated with resilience, such as individual behavioral traits and social support. We then explain the physiological response to stress and how it is modulated by resilience factors. In the subsequent section, we describe the animal models commonly used in the study of resilience to social stress, and we focus on the effects of chronic social defeat (SD), a kind of stress induced by repeated experience of defeat in an agonistic encounter, on different animal behaviors (depression- and anxiety-like behavior, cognitive impairment and addiction-like symptoms). We then summarize the current knowledge on the neurobiological substrates of resilience derived from studies of resilience to the effects of chronic SD stress on depression- and anxiety-related behaviors in rodents. Finally, we focus on the limited studies carried out to explore resilience to the effects of SD stress on the rewarding properties of drugs of abuse, describing the current state of knowledge and suggesting future research directions.

Stress-induced alterations of mesocortical and mesolimbic dopaminergic pathways

Our ability to develop the cognitive strategies required to deal with daily-life stress is regulated by region-specific neuronal networks. Experimental evidence suggests that prolonged stress in mice induces depressive-like behaviors via morphological, functional and molecular changes affecting the mesolimbic and mesocortical dopaminergic pathways. Yet, the molecular interactions underlying these changes are still poorly understood, and whether they affect males and females similarly is unknown. Here, we used chronic social defeat stress (CSDS) to induce depressive-like behaviors in male and female mice. Density of the mesolimbic and mesocortical projections was assessed via immuno-histochemistry combined with Sholl analysis along with the staining of activity-dependent markers pERK and c-fos in the ventral tegmental area (VTA), nucleus accumbens (NAc) and medial prefrontal cortex (mPFC). Our results show that social stress decreases the density of TH+ dopaminergic axonal projections in the deep layers of the mPFC in susceptible but not resilient male and female mice. Consistently, our analyses suggest that pERK expression is decreased in the mPFC but increased in the NAc following CSDS in males and females, with no change in c-fos expression in both sexes. Overall, our findings indicate that social defeat stress impacts the mesolimbic and mesocortical pathways by altering the molecular interactions regulating somatic and axonal plasticity in males and females.

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.

Opioid System Contributes to the Trifluoromethyl-Substituted Diselenide Effectiveness in a Lifestyle-Induced Depression Mouse Model

Energy-dense foods and ethanol consumption are associated with mood disorders. m-Trifluoromethyl-diphenyl diselenide [(m-CF₃-PhSe)₂] has been a prominent pharmacological target due to its antidepressant-like effects. This study investigated if the modulation of opioid and glucocorticoid receptors and its well-known antioxidant property contribute to the (m-CF₃-PhSe)₂ antidepressant-like effect in young mice subjected to an energy-dense diet and ethanol intake. Swiss male mice [postnatal day (PND) 25] were exposed to an energy-dense diet (containing 20% fat and 20% carbohydrate) or standard chow until the PND 67. Mice received ethanol (2 g/kg) or water administration (3 times a week, intragastrically [i.g.]) from PND 45 to PND 60. After that, mice received (m-CF₃-PhSe)₂ (5 mg/kg/day; i.g) or vegetal oil administration from PND 60 to 66. Mice performed the behavioral tests to evaluate the depressive-like phenotype. The results showed that individually neither an energy-dense diet nor ethanol group induced a depressive-like phenotype, but the association of both induced this phenotype in young mice. Oxidative stress was characterized by the increase of malondialdehyde, the decrease in the superoxide dismutase activity, and non-protein sulfhydryl levels in the cerebral cortex of depressive-like mice. Depressive-like mice showed an increase in the protein levels of opioid receptors and depletion in those of glucocorticoid. (m-CF₃-PhSe)₂ abolished depressive-like phenotype and oxidative stress as well as modulated the levels of glucocorticoid and opioid receptors. In conclusion, the modulation of opioid and glucocorticoid receptors and the antioxidant property contributed to the (m-CF₃-PhSe)₂ antidepressant-like effect in young mice exposed to an energy-dense diet and ethanol intake.

Turning the 'Tides on Neuropsychiatric Diseases: The Role of Peptides in the Prefrontal Cortex

Recent advancements in technology have enabled researchers to probe the brain with the greater region, cell, and receptor specificity. These developments have allowed for a more thorough understanding of how regulation of the neurophysiology within a region is essential for maintaining healthy brain function. Stress has been shown to alter the prefrontal cortex (PFC) functioning, and evidence links functional impairments in PFC brain activity with neuropsychiatric disorders. Moreover, a growing body of literature highlights the importance of neuropeptides in the PFC to modulate neural signaling and to influence behavior. The converging evidence outlined in this review indicates that neuropeptides in the PFC are specifically impacted by stress, and are found to be dysregulated in numerous stress-related neuropsychiatric disorders including substance use disorder, major depressive disorder (MDD), posttraumatic stress disorder, and schizophrenia. This review explores how neuropeptides in the PFC function to regulate the neural activity, and how genetic and environmental factors, such as stress, lead to dysregulation in neuropeptide systems, which may ultimately contribute to the pathology of neuropsychiatric diseases.

Endogenous Opiates and Behavior: 2018

This paper is the forty-first consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2018 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (2), the roles of these opioid peptides and receptors in pain and analgesia in animals (3) and humans (4), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (5), opioid peptide and receptor involvement in tolerance and dependence (6), stress and social status (7), learning and memory (8), eating and drinking (9), drug abuse and alcohol (10), sexual activity and hormones, pregnancy, development and endocrinology (11), mental illness and mood (12), seizures and neurologic disorders (13), electrical-related activity and neurophysiology (14), general activity and locomotion (15), gastrointestinal, renal and hepatic functions (16), cardiovascular responses (17), respiration and thermoregulation (18), and immunological responses (19).

Neuroinflammation, Pain and Depression: An Overview of the Main Findings

Chronic pain is a serious public health problem with a strong affective-motivational component that makes it difficult to treat. Most patients with chronic pain suffer from severe depression; hence, both conditions coexist and exacerbate one another. Brain inflammatory mediators are critical for maintaining depression-pain syndrome and could be substrates for it. The goal of our paper was to review clinical and preclinical findings to identify the neuroinflammatory profile associated with the cooccurrence of pain and depression. In addition, we aimed to explore the regulatory effect of neuronal reorganization on the inflammatory response in pain and depression. We conducted a quantitative review supplemented by manual screening. Our results revealed inflammatory signatures in different preclinical models and clinical articles regarding depression-pain syndrome. We also identified that improvements in depressive symptoms and amelioration of pain can be modulated through direct targeting of inflammatory mediators, such as cytokines and molecular inhibitors of the inflammatory cascade. Additionally, therapeutic targets that improve and regulate the synaptic environment and its neurotransmitters may act as anti-inflammatory compounds, reducing local damage-associated molecular patterns and inhibiting the activation of immune and glial cells. Taken together, our data will help to better elucidate the neuroinflammatory profile in pain and depression and may help to identify pharmacological targets for effective management of depression-pain syndrome.

Crystal structure of catena-poly[tetrakis(μ2-trifluoroacetato-κ2 O:O′)(μ2-2,5-dimethylpyrazine-κ2 N,N′)dicopper(II)], C7H4CuF6NO4

C7H4CuF6NO4, triclinic, P1̄ (no. 2), a = 8.5122(5) Å, b = 8.5458(6) Å, c = 8.8674(6) Å, α = 75.042(3)°, β = 68.601(2)°, γ = 89.809(3)°, V = 577.26(7) Å3, Z = 2, Rgt (F) = 0.0247, wR ref(F 2) = 0.0625, T = 152.41 K.

m-Trifluoromethyl-diphenyl diselenide (m-CF3-PhSe)2 modulates the hippocampal neurotoxic adaptations and abolishes a depressive-like phenotype in a short-term morphine withdrawal in mice

The opioid withdrawal syndrome is defined as a complex phenomenon involving multiple cellular adaptations, which leads to the emergence of aversive physical and affective signs. The m-trifluoromethyl-diphenyl diselenide (m-CF₃-PhSe)₂ elicits an antidepressant-like effect by modulating the opioid system in different animal models of mood disorders. Notably, repeated exposure to (m-CF₃-PhSe)₂ developed neither tolerance nor withdrawal signs in mice. The aim of the present study was to investigate whether (m-CF₃-PhSe)₂ attenuates the physical signs and the depressive-like phenotype during morphine withdrawal through its neuroprotective effects on oxidative stress, the NMDA receptor and the proBDNF/mBDNF signaling in the hippocampus of mice. Adult Swiss mice received saline solution or escalating doses (20-100 mg/kg, sc) of morphine for six days. For the next three days, the animals were treated with canola oil, (m-CF₃-PhSe)₂ (5 and 10 mg/kg, ig) or methadone (5 mg/kg, sc) whereas morphine injections were discontinued. On day 9, physical withdrawal signs and depressive-like behavior were assessed 30 min after the last administration of (m-CF₃-PhSe)_2. Although short-term treatment with (m-CF₃-PhSe)₂ at both doses suppressed the aversive physical and affective signs in morphine withdrawn-mice, the highest dose of (m-CF₃-PhSe)₂ per se increased the teeth chattering manifestation. The intrinsic antioxidant property of (m-CF₃-PhSe)₂ modulated oxidative stress, it also restored the NMDA receptor levels in the hippocampus of morphine withdrawn-mice. Besides, (m-CF₃-PhSe)₂ downregulated the proBDNF/p-75^NTR/JNK pro-apoptotic pathway without affecting the mBDNF/TrkB/ERK/CREB pro-survival signaling in the hippocampus of morphine withdrawn-mice. The results show that (m-CF₃-PhSe)₂ treatment modulated the hippocampal neurotoxic adaptations and abolished the depressive-like phenotype following morphine withdrawal in mice.

Social defeat-induced increase in the conditioned rewarding effects of cocaine: Role of CX3CL1

Social stress is associated with higher vulnerability to drug use, as it enhances the reinforcing effects of psychostimulants in rodents. Furthermore, continued or severe stress induces a proinflammatory state of microglial activation and augmented cytokine production. The aim of the present work was to evaluate the role of fractalkine [C-X3-C motif ligand 1 (CX3CL1)], an inflammatory chemokine, in the increased conditioned rewarding effects of cocaine in animals exposed to social defeat stress. In addition, we measured the signaling cascade pathway of CX3CL1 in the hippocampus (HPC) (including p-ERK/ERK, p-p38/p38 MAPK, p-p65/p65 NFκB and p-CREB/CREB ratios). The glutamate receptor subunits NR1, NR2B and GluA1 were also assessed. A total of 102 adult male C57BL/6 J wild-type (WT) and Cx3cr1 knockout (KO) mice were divided into different experimental groups according to stress condition (exploration or social defeat). Three weeks after the last social defeat, conditioned place preference (CPP) was induced by a subthreshold dose of cocaine (1 mg/kg). Brain tissue samples were taken 24 h after the CPP procedure to determine the levels of the proteins and transcription factors. Our results showed that, in WT animals, repeated social defeat (RSD) decreased CX3CL1 striatal levels without producing changes in the HPC. In addition, RSD induced an increase in the conditioned rewarding effects of cocaine, regardless of the genotype. After CPP induced by cocaine, defeated Cx3cr1-deficient mice showed a decrease in the p-p65/p65 NFκB and pCREB/CREB ratio in the HPC, and an increase in the hippocampal levels of CX3CL1 and p-p38/p38 MAPK relation. In all defeated mice, there was a decrease in the ionotropic glutamate receptor subunit NR1. In conclusion, these results suggest that the lack of CX3CL1/Cx3cr1 signaling under stress conditions induces changes in protein and transcription factors, indicating that CX3CL1 is needed to shield the response to social defeat.

Kappa Opioid Receptor Antagonists as Potential Therapeutics for Stress-Related Disorders

Exposure to stressful stimuli activates kappa opioid receptor (KOR) signaling, a process known to produce aversion and dysphoria in humans and other species. This endogenous opioid system is dysregulated in stress-related disorders, specifically in major depressive disorder (MDD). These findings serve as the foundation for a growing interest in the therapeutic potential of KOR antagonists as novel antidepressants. In this review, data supporting the hypothesis of dysregulated KOR function in MDD are considered. The clinical data demonstrating the therapeutic efficacy and safety of selective and mixed opioid antagonists are then presented. Finally, the preclinical evidence illustrating the induction of behaviors relevant to the endophenotypes of MDD and KOR antagonist activity in stress-naïve and stress-exposed animals is evaluated. Overall, this review highlights the emergent literature supporting the pursuit of KOR antagonists as novel therapeutics for MDD and other stress-related disorders.

Multi-target-directed-ligands acting as enzyme inhibitors and receptor ligands

In this review, we present the latest advances in the field of multi-target-directed ligand (MTDL) design for the treatment of various complex pathologies of multifactorial origin. In particular, latest findings in the field of MTDL design targeting both an enzyme and a receptor are presented for different diseases such as Alzheimer's disease (AD), depression, addiction, glaucoma, non-alcoholic steatohepatitis and pain and inflammation. The ethology of the diseases is briefly described, with special emphasis on how the MTDL can evolve into novel therapies that replace the classic pharmacological dogma "one target one disease". Considering the current needs for therapy adherence improvement, it is exposed as from the medicinal chemistry, different molecular scaffolds are studied. With the use of structure activity relationship studies and molecular optimization, new hybrid molecules are generated with improved biological properties acting at two biologically very distinct targets.

Voluntary Wheel Running Reverses Deficits in Social Behavior Induced by Chronic Social Defeat Stress in Mice: Involvement of the Dopamine System

Voluntary exercise has been reported to have a therapeutic effect on many psychiatric disorders and social stress is known to impair social interaction. However, whether voluntary exercise could reverse deficits in social behaviors induced by chronic social defeat stress (CSDS) and the underlying mechanism remain unclear. The present study shows CSDS impaired social preference and induced social interaction deficiency in susceptible mice. Voluntary wheel running (VWR) reversed these effects. In addition, CSDS decreased the levels of tyrosine hydroxylase in the ventral tegmental area and the D2 receptor (D2R) in the nucleus accumbens (NAc) shell. These changes can be recovered by VWR. Furthermore, the recovery effect of VWR on deficits in social behaviors in CSDS mice was blocked by the microinjection of D2R antagonist raclopride into the NAc shell. Thus, these results suggest that the mechanism underlying CSDS-induced social interaction disorder might be caused by an alteration of the dopamine system. VWR may be a novel means to treat CSDS-induced deficits in social behaviors via modifying the dopamine system.

JNK Regulation of Depression and Anxiety

Depression and anxiety are the most common mood disorders affecting 300 million sufferers worldwide. Maladaptive changes in the neuroendocrine stress response is cited as the most common underlying cause, though how the circuits underlying this response are controlled at the molecular level, remains largely unknown. Approximately 40% of patients do not respond to current treatments, indicating that untapped mechanisms exist. Here we review recent evidence implicating JNK in the control of anxiety and depressive-like behavior with a particular focus on its action in immature granule cells of the hippocampal neurogenic niche and the potential for therapeutic targeting for affective disorders.

m-Trifluoromethyl-diphenyl Diselenide Regulates Prefrontal Cortical MOR and KOR Protein Levels and Abolishes the Phenotype Induced by Repeated Forced Swim Stress in Mice

The present study aimed to investigate the m-trifluoromethyl-diphenyl diselenide [(m-CF₃-PhSe)₂] effects on prefrontal cortical MOR and KOR protein levels and phenotype induced by repeated forced swim stress (FSS) in mice. Adult Swiss mice were subjected to repeated FSS sessions, and after that, they performed the spontaneous locomotor/exploratory activity, tail suspension, and splash tests. (m-CF₃-PhSe)₂ (0.1 to 5 mg/kg) was administered to mice 30 min before the first FSS session and 30 min before the subsequent repeated FSS. (m-CF₃-PhSe)₂ abolished the phenotype induced by repeated FSS in mice. In addition, a single FSS session increased μ but reduced δ-opioid receptor contents, without changing the κ content. Mice subjected to repeated FSS had an increase in the μ content when compared to those of naïve group or subjected to single FSS. Repeated FSS induced an increase of δ-opioid receptor content compared to those mice subjected to single FSS. However, the δ-opioid receptor contents were lower than those found in the naïve group. The mice subjected to repeated FSS showed an increase in the κ-opioid receptor content when compared to that of the naïve mice. (m-CF₃-PhSe)₂ regulated the protein contents of μ and κ receptors in mice subjected to repeated FSS. These findings demonstrate that (m-CF₃-PhSe)₂ was effective to abolish the phenotype induced by FSS, which was accompanied by changes in the contents of cortical μ- and κ-opioid receptors.