Prevention of chronic stress-induced depression-like behavior by inducible nitric oxide inhibitor

Probiotic Bactolac alleviates depression-like behaviors by modulating BDNF, NLRP3 and MC4R levels, reducing neuroinflammation and promoting neural repair in rat model

Depression, a prevalent psychiatric disorder, exerts severe and debilitating impacts on an individual's mental and physical well-being, and it is considered a chronic mental illness. Chronic stress plays an important role in the pathophysiology of depression. Lactobacillus plantarum and Streptococcus thermophilus are psychobiotic bacteria and synthesize some neurotransmitters that play a role in the pathogenesis of depression. In this study, we aimed to investigate the therapeutic effects of Bactolac (Lactobacillus plantarum NBIMCC 8767  + Streptococcus thermophilus NBIMCC 8258) on chronic stress-induced depression in rats. Behavioral tests, including the sucrose preference test, elevated plus maze test, forced swim test, and three-chamber sociability test, were employed to assess depressive and anxiety-like behaviors. The expression level of the 5-HT1A, DRD1, ADRA-2A, GABA-A α1, CNR1, NR3C2, NOD1, NLRP3 and MC4R; BDNF levels, glial activity and intestinal permeability were determined in chronic stress-induced depression in rats. In conclusions, chronic stress decreased the expression levels of 5-HT1A, DRD1, ADRA-2A, GABA-A α1, CNR1, NR3C2, NOD1 and BDNF level; increased the expression levels of NLRP3 and MC4R, caused neurodegeneration and glial activity, ultimately led to depressive effects. Bactolac was effective in reducing depressive-like behaviors according to the results of behavioral tests. Bactolac treatment provided high neuronal survival rate increasing BDNF level, prevented the excessive release of pro-inflammatory cytokines by reducing the expression levels of NLRP3 and MC4R, therefore, prevented the excessive activation of the hypothalamus-pituitary-adrenal (HPA) axis and accordingly, reduced neurodegeneration and glial cell activation in depressed rats. We can suggest that Bactolac supplementation may be beneficial in coping with stress, alleviate the effects of chronic stress and help to protect mental health.

Mucuna pruriens, a Possible Treatment for Depressive Disorders

Depression is a mental disorder that depicts a wide variety of symptoms, including mood and cognitive alterations, as well as recurrent thoughts of death or suicide. It could become the second leading cause of premature death or disability worldwide. Treatments with conventional antidepressants have several limitations in terms of effectiveness, side effects, and high costs. Therefore, medicinal plants such as Mucuna pruriens are potent candidates for treating depressive disorders. This review shows a compendium of evidence supporting the antidepressant effect of the Mucuna pruriens plant in diverse animal models. This includes the mechanisms of action underlying the antidepressant activity of the treatment concerning dopamine, serotonin, norepinephrine, reactive oxygen species, nitric oxide, cortisol, and inflammation. Clinical trials are needed to study the efficacy and safety of Mucuna pruriens for depression.

Neural substrates for regulating self-grooming behavior in rodents

Grooming, as an evolutionarily conserved repetitive behavior, is common in various animals, including humans, and serves essential functions including, but not limited to, hygiene maintenance, thermoregulation, de-arousal, stress reduction, and social behaviors. In rodents, grooming involves a patterned and sequenced structure, known as the syntactic chain with four phases that comprise repeated stereotyped movements happening in a cephalocaudal progression style, beginning from the nose to the face, to the head, and finally ending with body licking. The context-dependent occurrence of grooming behavior indicates its adaptive significance. This review briefly summarizes the neural substrates responsible for rodent grooming behavior and explores its relevance in rodent models of neuropsychiatric disorders and neurodegenerative diseases with aberrant grooming phenotypes. We further emphasize the utility of rodent grooming as a reliable measure of repetitive behavior in neuropsychiatric models, holding promise for translational psychiatry. Herein, we mainly focus on rodent self-grooming. Allogrooming (grooming being applied on one animal by its conspecifics via licking or carefully nibbling) and heterogrooming (a form of grooming behavior directing towards another animal, which occurs in other contexts, such as maternal, sexual, aggressive, or social behaviors) are not covered due to space constraints.

Nerolidol reduces depression-like behavior in mice and suppresses microglia activation by down-regulating DNA methyltransferase 1

Modern medicine has unveiled that essential oil made from Aquilaria possesses sedative and hypnotic effects. Among the chemical components in Aquilaria, nerolidol, a natural sesquiterpene alcohol, has shown promising effects. This study aimed to unravel the potential of nerolidol in treating depression. Chronic unpredictable mild stress (CUMS) was utilized to induce depression-like behavior in mice, and open field test, sucrose preference, and tail suspension test was conducted. The impacts of nerolidol on the inflammatory response, microglial activation, and DNA methyltransferase 1 (DNMT1) were assessed. To study the regulatory role of DNMT1, lipopolysaccharide (LPS) was used to treat BV2 cells, followed by the evaluation of cell viability and DNMT1 level. Additionally, the influence of DNMT1 overexpression on BV2 cell activation was determined. Behavioral analysis revealed that nerolidol reduced depression-like behavior in mice. Nerolidol reduced the levels of inflammatory factors and microglial activation caused by CUMS. Nerolidol treatment was found to reduce DNMT1 levels in mouse brain tissue and it also decrease the LPS-induced increase in DNMT1 levels in BV2 cells. DNMT1 overexpression reversed the impacts of nerolidol on the inflammation response and cell activation. This study underscores the potential of nerolidol in reducing CUMS-induced depressive-like behavior and inhibiting microglial activation by downregulating DNMT1. These findings offer valuable insights into the potential of nerolidol as a therapeutic option for depression.

Anethole as a promising antidepressant for maternal separation stress in mice by modulating oxidative stress and nitrite imbalance

The occurrence of major depressive disorder is widespread and can be observed in individuals belonging to all societies. It has been suggested that changes in the NO pathway and heightened oxidative stress may play a role in developing this condition. Anethole is a diterpene aromatic compound found in the Umbelliferae, Apiaceae, and Schisandraceae families. It has potential pharmacological effects like antioxidant, anxiolytic, analgesic, anti-inflammatory, antidiabetic, gastroprotective, anticancer, estrogenic, and antimicrobial activities. This study aimed to investigate the potential antidepressant properties of Anethole in a mouse model experiencing maternal separation stress while also examining its impact on oxidative stress and nitrite levels. The research involved the participation of 40 male NMRI mice, separated into five distinct groups to conduct the study. The control group was administered 1 ml/kg of normal saline, while the MS groups were given normal saline and Anethole at 10, 50, and 100 mg/kg doses. The study comprised various behavioural tests, including the open field test (OFT), forced swimming test (FST), and splash test, to assess the effects of Anethole on the mice. In addition to the behavioural tests, measurements were taken to evaluate the total antioxidant capacity (TAC), malondialdehyde (MDA), and nitrite levels in the hippocampus of the mice. According to the findings, maternal separation stress (MS) led to depressive-like conduct in mice, including a rise in immobility duration during the FST and a reduction in the duration of grooming behaviour in the splash test. Additionally, the results indicated that MS correlated with an increase in the levels of MDA and nitrite and a reduction in the TAC in the hippocampus. However, the administration of Anethole resulted in an increase in grooming activity time during the splash test and a decrease in immobility time during the FST. Anethole also exhibited antioxidant characteristics, as demonstrated by its ability to lower MDA and nitrite levels while increasing the TAC in the hippocampus. The results suggest that Anethole may have an antidepressant-like impact on mice separated from their mothers, likely partly due to its antioxidant properties in the hippocampus.

The antidepressant-like effect of doxycycline is associated with decreased nitric oxide metabolite levels in the prefrontal cortex

Doxycycline is an antibiotic that has shown neuroprotective, anti-inflammatory, and antidepressant-like effects. Low doses of doxycycline revert the behavioral and neuroinflammatory responses induced by lipopolysaccharide treatment in a mice model of depression. However, the molecular mechanisms involved in the antidepressant action of doxycycline are not yet understood. Doxycycline inhibits the synthesis of nitric oxide (NO), which increases after stress exposure. Inducible NO synthase (iNOS) inhibition also causes antidepressant-like effects in animal models sensitive to antidepressant-like effects such as the forced swimming test (FST). However, no direct study has yet investigated if the antidepressant-like effects of doxycycline could involve changes in NO-mediated neurotransmission. Therefore, this study aimed at investigating: i) the behavioral effects induced by doxycycline alone or in association with ineffective doses of a NO donor (sodium nitroprusside, SNP) or an iNOS inhibitor (1400 W) in mice subjected to the FST; and ii) doxycycline effects in NO metabolite levels in the prefrontal cortex and hippocampus these animals. Male mice (8 weeks) received i.p. injection of saline or doxycycline (10, 30, and 50 mg/kg), alone or combined with SNP (0.1, 0.5, and 1 mg/kg) or 1400 W (1, 3, and 10 µg/kg), and 30 min later were submitted to the FST. Animals were sacrificed immediately after, and NO metabolites nitrate/nitrite (NOx) were measured in the prefrontal cortex and hippocampus. Doxycycline (50 mg/kg) reduced both the immobility time in the FST and NOx levels in the prefrontal cortex of mice compared to the saline group. The antidepressant-like effect of doxycycline in the FST was prevented by SNP (1 mg/kg) pretreatment. Additionally, sub-effective doses of doxycycline (30 mg/kg) associated with 1400 W (1 µg/kg) induced an antidepressant-like effect in the FST. Altogether, our data suggest that the reducing NO levels in the prefrontal cortex through inhibition of iNOS could be related to acute doxycycline treatment resulting in rapid antidepressant-like effects in mice.

Combined metabolomics and transcriptomics analysis of rats under neuropathic pain and pain-related depression

Neuropathic pain often leads to negative emotions, which in turn can enhance the sensation of pain. This study aimed to investigate the molecular mechanisms mediating neuropathic pain and negative emotions. Chronic constriction injury (CCI) rats were used as model animals and behavioral tests were conducted to assess pain and negative emotions. Then, the rat anterior cingulate cortex (ACC) was analyzed using UPLC-MS/MS and subsequently integrated with our previously published transcriptome data. Metabolomics analysis revealed that 68 differentially expressed metabolites (DEMs) were identified, mainly in amino acid metabolites and fatty acyls. Combined with our previously published transcriptome data, we predicted two genes that potentially exhibited associations with these metabolites, respectively Apolipoprotein L domain containing 1 (Apold1) and WAP four-disulfide core domain 1 (Wfdc1). Taken together, our results indicated that peripheral nerve injury contributing to neuropathic pain and pain-related depression may be associated with these metabolites and genes. This research provides new insights into the molecular regulatory mechanism, which could serve as a reference for the treatment of neuropathic pain and pain-related depression.

Music prevents stress-induced depression and anxiety-like behavior in mice

Depression is the most prevalent psychiatric disorder worldwide and remains incurable; however, there is little research on its prevention. The leading cause of depression is stress, and music has been hypothesized to alleviate stress. To examine the potential beneficial effects of music on stress and depression, we subjected mice to chronic unpredictable mild stress (CUMS) during the day and music at night. Strikingly, our results indicated that music completely prevented CUMS-induced depression and anxiety-like behaviors in mice, as assessed by the open field, tail suspension, sucrose preference, novelty suppressed feeding, and elevated plus maze tests. We found that listening to music restored serum corticosterone levels in CUMS mice, which may contribute to the beneficial effects of music on the mouse brain, including the restoration of BDNF and Bcl-2 levels. Furthermore, listening to music prevented CUMS-induced oxidative stress in the serum, prefrontal cortex, and hippocampus of mice. Moreover, the CUMS-induced inflammatory responses in the prefrontal cortex and hippocampus of mice were prevented by listening to music. Taken together, we have demonstrated for the first time in mice experiments that listening to music prevents stress-induced depression and anxiety-like behaviors in mice. Music may restore hypothalamus-pituitary-adrenal axis homeostasis, preventing oxidative stress, inflammation, and neurotrophic factor deficits, which had led to the observed phenotypes in CUMS mice.

Ninjinyoeito Prevents Onset of Depression-Like Behavior and Reduces Hippocampal iNOS Expression in Senescence-Accelerated Mouse Prone 8 Mice

Late-life depression is a globally prevalent disorder. Ninjinyoeito (NYT), a traditional Japanese herbal medicine, attenuates depressive symptoms in older patients. However, the mechanisms underlying the antidepressive effect of NYT are unknown. In this study, we investigated the mechanism of the action of NYT using senescence-accelerated mouse prone 8 (SAMP8) mice, which exhibit accelerated aging. SAMP8 mice were treated with NYT starting at 12 weeks of age. Twelve-week-old SAMP8 mice did not show prolonged immobility time in the tail suspension test compared with age-matched SAMR1 mice (normal aging control). At 34 weeks of age, vehicle-treated SAMP8 mice displayed prolonged immobility time compared with SAMR1 mice. NYT-treated SAMP8 mice showed a shorter immobility time than that of vehicle-treated SAMP8 mice. Notably, NYT decreased hippocampal inducible nitric oxide synthase (iNOS) expression in SAMP8 mice. There was no difference in iNOS expression between SAMR1 and vehicle-treated SAMP8 mice. Subchronic (5 days) administration of an iNOS inhibitor, 1400 W, shortened the immobility time in SAMP8 mice. These results suggest that NYT prevents an increase in immobility time of SAMP8 mice by decreasing iNOS levels in the hippocampus. Therefore, the antidepressive effect of NYT in older patients might be mediated, at least in part, by the downregulation of iNOS in the brain. Our data suggest that NYT is useful to prevent the onset of depression with aging.

Achyranthes aspera ameliorates stress induced depression in mice by regulating neuroinflammatory cytokines

Background and aim

Achyranthes aspera Linn. (A. aspera) (family: Amaranthaceae) is highly recognized in ethnomedicine and traditional systems of Indian medicine as a nervine restorative for several psychiatric disorders. Study presented here was designed to appraise the antidepressant-like effects of A. aspera in murine model of chronic unpredictable mild stress (CUMS) induced depression.

Experimental procedures-

Rodents were exposed to different stressor in unpredictive manner during CUMS protocol once a day for 4 weeks. Mice were intraperitoneally injected with A. aspera extract (2.5, 5 and 10 mg/kg) or fluoxetine (10 mg/kg) or betaine (20 mg/kg) once daily during day 15–28 of the CUMS protocol. Sucrose preference, motivation and self-care, immobility latency and plasma corticosterone were evaluated after 24 h of last stressor. After behavioral assessments TNF-α, Il-6 and BDNF immunocontent was determined in hippocampus and prefrontal cortex.

Results and conclusion

A. aspera extract as well as betaine improved sucrose preference, increased grooming frequency and latency in splash test and ameliorated depression-like condition in CUMS mice in Porsolt test. A. aspera treatment decreased the elevated plasma corticosterone and reversed the effect of CUMS on TNF-α, Il-6 and BDNF immunocontent in mice. The results of the present study suggest A. aspera as a promising indigenous medicine for stress associated neurobehavioral and comorbid complications.

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Achyranthes aspera is a recognized medicine for psychiatric disorders.

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A. aspera improved sucrose preference, increased grooming frequency and latency in splash test in CUMS mice.

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A. aspera ameliorated depression-like condition in CUMS mice.

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A. aspera treatment decreased the elevated plasma corticosterone and reversed the effect of CUMS on TNF-α, Il-6 and BDNF immunocontent in mice.

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Results suggest A. aspera as a medicine for stress associated neurobehavioral and comorbid complications.

Kamikihito rescued depressive-like behaviors and hippocampus neurogenesis in chronic restraint stress rats

Background and aim

Substantial evidence suggests the effectiveness of plant-based medicine in stress-related diseases. Kamikihito (KKT), a Japanese traditional herbal medicine (Kampo), has been used for anemia, insomnia, and anxiety. Recent studies revealed its ameliorating effect on cognitive and memory dysfunction in several animal models. We, therefore, determined whether daily supplementation of KKT has an antidepressant-like effect on the stress-induced behavioral and neurological changes in rats.

Experimental procedure

The effect of KKT against the stress-induced changes in anxiety- and depressive-like behaviors and hippocampal neurogenesis were determined using a rat model of chronic restraint stress (CRS). KKT was orally administered daily at 300 or 1000 mg/kg during 21 consecutive days of CRS (6 h/day). The effect of CRS and KKT on physiological parameters, including body weight gain, food/water consumptions, plasma corticosterone (CORT) levels, and percentage of adrenal gland weight to body weight, were firstly measured. Anxiety- and depressive-like behaviors in rats were assessed in the open field test (OFT), sucrose preference test (SPT), and forced swimming test (FST). Hippocampal neurogenesis was determined by immunohistochemistry.

Results and conclusion

CRS for 21 days caused a significant decrease in body weight gain and increase in plasma CORT levels and percentage of adrenal gland weight to body weight, which were rescued by KKT treatment. KKT also suppressed the CRS-induced anxiety- and depressive-like behaviors and impairment of hippocampal neurogenesis. These results suggest that daily treatment of KKT has a protective effect against physiological, neurological, and behavioral changes in a rat model of depression.

A transcriptomic analysis of neuropathic pain in the anterior cingulate cortex after nerve injury

The anterior cingulate cortex (ACC) is a core brain region processing pain emotion. In this study, we performed RNA sequencing analysis to reveal transcriptomic profiles of the ACC in a rat chronic constriction injury (CCI) model. A total of 1628 differentially expressed genes (DEGs) were identified by comparing sham-operated rats with rats of 12 hours, 1, 3, 7, and 14 days after surgery, respectively. Although these inflammatory-related DEGs were generally increased after CCI, different kinetics of time-series expression were observed with the development of neuropathic pain affection. Specifically, the expression of Ccl5, Cxcl9 and Cxcl13 continued to increase following CCI. The expression of Ccl2, Ccl3, Ccl4, Ccl6, and Ccl7 were initially upregulated after CCI and subsequently decreased after 12 hours. Similarly, the expression of Rac2, Cd68, Icam-1, Ptprc, Itgb2, and Fcgr2b increased after 12 hours but reduced after 1 day. However, the expression of the above genes increased again 7 days after CCI, when the neuropathic pain affection had developed. Furthermore, gene ontology analysis, Kyoto Encyclopedia of Genes and Genomes pathway enrichment and interaction network analyses further showed a high connectivity degree among these chemokine targeting genes. Similar expressional changes in these genes were found in the rat spinal dorsal horn responsible for nociception processing. Taken together, our results indicated chemokines and their targeting genes in the ACC may be differentially involved in the initiation and maintenance of neuropathic pain affection. These genes may be a target for not only the nociception but also the pain affection following nerve injury.

Inducible Nitric Oxide Synthase Inhibition in the Medial Prefrontal Cortex Attenuates the Anxiogenic-Like Effect of Acute Restraint Stress via CB1 Receptors

Stress exposure can result in several proinflammatory alterations in the brain, including overexpression of the inducible isoform of nitric oxide synthase (iNOS) in the medial prefrontal cortex (mPFC). These changes may be involved in the development of many psychiatric conditions. However, it is unknown if iNOS in mPFC plays a significant role in stress-induced behavioral changes. The endocannabinoid (ECB) system is also influenced by stress. Its activation seems to be a counter regulatory mechanism to prevent or decrease the stress-mediated neuroinflammatory consequences. However, it is unclear if the ECB system and iNOS interact to influence stress consequences. This study aimed to test the hypothesis that the anti-stress effect of iNOS inhibition in mPFC involves the local ECB system, particularly the CB₁ cannabinoid receptors. Male Wistar rats with guide cannula aimed at the mPFC were submitted to acute restraint stress (RS) for 2 h. In the following morning, rats received bilateral microinjections of vehicle, AM251 (CB₁ antagonist; 100 pmol), and/or 1400W (iNOS selective inhibitor; 10^-4, 10^-3, or 10^-2 nmol) into the prelimbic area of mPFC (PL-mPFC) before being tested in the elevated plus-maze (EPM). iNOS inhibition by 1400W prevented the anxiogenic-like effect observed in animals submitted to RS. The drug did not promote behavior changes in naive animals, demonstrating a stress-dependent effect. The 1400W-anti-stress effect was prevented by local pretreatment with AM251. Our data suggest that iNOS inhibition may facilitate the local endocannabinoid signaling, attenuating stress effects.

Crosstalk Among NLRP3 Inflammasome, ETBR Signaling, and miRNAs in Stress-Induced Depression-Like Behavior: a Modulatory Role for SGLT2 Inhibitors

Depression is an overwhelming health concern, and many patients fail to optimally respond to available standard therapies. Neuroplasticity and blood-brain barrier (BBB) integrity are the cornerstones of a well-functioning central nervous system, but they are vulnerable to an overly active NLRP3 inflammasome pathway that can also indirectly trigger the release of ET-1 and contribute to the ET system disturbance, which further damages stress resilience mechanisms. Here, the promising yet unexplored antidepressant potential of dapagliflozin (Dapa), a sodium-glucose co-transporter-2 inhibitor, was investigated by assessing its role in the modulation of the NLRP3 inflammasome pathway and ETBR signal transduction, and their impact on neuroplasticity and BBB integrity in an animal model of depression. Dapa (1 mg/kg/day; p.o.) with and without BQ-788 (1 mg/kg/day; i.p.), a specific ETBR blocker, were administered to adolescent male Wistar rats exposed to a 5-week chronic unpredictable stress protocol. The depressive animals demonstrated marked activation of the NLRP3 inflammasome pathway (NF-κB/NLRP3/caspase-1/IL/TNF-α), which was associated with both peripheral and central inflammatory responses. The ET system was disrupted, with noticeable reduction in miR-125a-5p and ETBR gene expression. Cortical ZO-1 expression was downregulated under the influence of NLRP3/TNF-α/miR-501-3p signaling, along with a prominent reduction in hippocampal BDNF and synapsin-1. With ETBR up-regulation being a cornerstone outcome, Dapa administration efficiently created an overall state of resilience, improved histopathological and behavioral variables, and preserved BBB function. These observations were further verified by the results obtained with BQ-788 co-administration. Thus, Dapa may exert its antidepressant action by reinforcing BBB integrity and promoting neuroplasticity through manipulation of the NLRP3/ET-1/ETBR/BDNF/ZO-1 axis, with a significant role for ETBR signaling. Graphical illustration for the proposed mechanisms of the anti-depressant potential of Dapa. Dapa suppressed NLRP3 inflammasome activation and assembly with subsequent inhibition of pro-inflammatory ILs. This results in attenuation of neuro-inflammation, BBB disruption, glial cell activation, TNF-α and ET-1 release, and the enhanced production of neurotrophins. The role of ETBR signaling was emphasized; Dapa possibly augmented ETBR expression, which is thought to boost neurotrophins production. The ETBR blocker, BQ-788, suppressed most of the positive outcomes of Dapa. Finally, miR-125a-5p and miR-501-3p that played major roles in these pathological pathways were modulated by Dapa. It is not yet clear whether Dapa has a direct or rather indirect effect on their expression. BBB, blood-brain barrier; Dapa, dapagliflozin; ET-1, endothelin-1; ETBR, endothelin B receptor; IL, interleukin; NF-κB, nuclear factor kappa B; NLRP3, nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain-containing protein 3; TNF-α, tumor necrosis factor-α. Created with BioRender.com.

Dietary EPA-Enriched Phospholipids Alleviate Chronic Stress and LPS-Induced Depression- and Anxiety-Like Behavior by Regulating Immunity and Neuroinflammation

SCOPE

A growing number of studies have reported the effects of eicosapentaenoic acid (EPA) and terrestrial phospholipids on ameliorating mood disorders. Marine-derived EPA-enriched phospholipids (EPA-PL) exhibit the structural characteristics of EPA and phospholipids. However, the effect of dietary EPA-PL, and the differences between amphiphilic EPA-PL and lyophobic EPA on mood disorders had not been studied.

METHODS AND RESULTS

A comparative investigation to determine the effects of dietary EPA-enriched ethyl ester (EPA-EE) and EPA-PL on improving depression- and anxiety-like behavior in a mouse model is performed, induced by 4 week chronic unpredictable mild stress (CUMS) coupled with lipopolysaccharide (LPS) challenge. It is found that dietary 4 week 0.6% (w/w) EPA-PL rescued depression- and anxiety-like behavior to a greater extent than did EPA-EE. Moreover, dietary EPA-PL significantly reduced the immobility time by 56.6%, close to the normal level, in forced swimming test, which revealed a reversal of depression-like behavior. Further studies revealed that dietary EPA-PL regulated immunity, monoamine systems, and the hypothalamic-pituitary-adrenal (HPA) axis by multi-target interactions, including inhibition of neuroinflammation and apoptosis.

CONCLUSION

EPA-PL exerted superior effects to EPA-EE in alleviating depression- and anxiety-like behavior. The data suggest potential novel candidate or targeted dietary patterns to prevent and treat mood disorder.

High Serum Levels of iNOS and MIP-1α are Associated with Post-Stroke Depression

PURPOSE

Post-stroke depression (PSD) is one of the emotional disorders after the onset of stroke. Many studies have indicated that inflammatory processes can promote the occurrence and development of PSD. The purpose of our study was to explore the potential relationship between PSD and two inflammatory biomarkers: inducible nitric oxide synthase (iNOS) and macrophage inflammatory protein 1α (MIP-1α).

METHODS

In total, 80 patients diagnosed with depression after the first-ever acute ischemic stroke were enrolled in PSD group consecutively. During the same period, 40 non-depressed patients following the first-ever acute ischemic stroke and 40 healthy control subjects were recruited as non-PSD group and normal group, respectively. All participants have performed serum iNOS and MIP-1α level examination with enzyme-linked immunosorbent assay (ELISA). The severity of depressive symptoms was evaluated by the 24-item Hamilton Depression Scale (HAMD-24).

RESULTS

Serum iNOS and MIP-1α levels were significantly higher in PSD group than those in non-PSD and normal groups (P < 0.001). Serum iNOS and MIP-1α levels of PSD patients with varying degrees of depression were significantly different, serum iNOS and MIP-1α levels became higher as the depressive symptoms became more severe (P < 0.05). There was a positive correlation between the elevated levels of iNOS, MIP-1α and HAMD scores (r = 0.262, 0.209, P < 0.05). Logistic regression analysis showed that both serum iNOS and MIP-1α levels were independently associated with PSD (OR = 2.790, 95% CI: 0.712-10.933, P < 0.05 and OR = 1.922, 95% CI: 0.648-9.815, P < 0.05, respectively) after adjustment for possible relevant confounders.

CONCLUSION

High serum levels of iNOS and MIP-1α were found to be associated with the development of PSD and closely related to its severity.

Behavioral and neurological improvement by Cydonia oblonga fruit extract in chronic immobilization stress rats

It is known that chronic stress is a contributing factor to several physical and mental diseases. In this study, we examined the effect of hydroethanolic extract of Cydonia oblonga fruit (HECO, 300 mg/kg) in chronically immobilized rats on physiological and behavioral parameters by the open field test (OFT), sucrose preference test (SPT), and forced swimming test (FST) and on neurological alterations by analysis of the hippocampal neurogenesis. A daily 6 hr exposure to chronic immobilization stress (CIS) for 21 consecutive days induced anxiety- and depressive-like behaviors in rats' concomitant with decreased weight gain and increased plasma corticosterone (CORT) levels, rats also showed atrophy in the CA3 subregion of the hippocampus and a decreased number of Ki67 and DCX positive cells in the dentate gyrus (DG). Treatment with HECO successfully suppressed the physiological and behavioral markers of the CIS and prevents the structural abnormality and the impaired cell proliferation in the hippocampus. Moreover, the daily administration of HECO improved the mood function in normal rats. Taking together, our findings demonstrate, for the first time, the anti-depressive effect of C. oblonga fruit by enhancing the hippocampal neurogenesis in the rat model of depression.

Inhibition of P2X7R in the amygdala ameliorates symptoms of neuropathic pain after spared nerve injury in rats

The amygdala circuitry and P2X7 receptor (P2X7R) have both been shown to play important roles in the modulation of neuropathic pain (NP). However, little is known about the functional role of P2X7R in the amygdala for the regulation of NP. This study aims to evaluate the alleviative effect of intra-amygdala microinfusion of a pharmacological antagonist of P2X7R (A-438079) on NP and explore its possible mechanism of action. Male Sprague-Dawley rats were used to construct the animal model of NP through spared nerve injury (SNI). The SNI rats randomly received chronic bilateral microinjection of A-438079 (100 pmol/side) or saline into the amygdalae via cannulas. Mechanical paw withdrawal threshold (MWT) and thermal withdrawal duration (TWD) were measured by von Frey monofilaments. Besides, tail suspension test (TST), forced swimming test (FST), open field test (OFT) and sucrose preference test (SPT) were performed to assess depression- and anxiety-like behaviors. Immunofluorescence assay was employed to determine the levels of glial fibrillary acidic protein (GFAP), ionized calcium binding adaptor molecule 1 (IBA-1) and connexin 43 (Cx43) in the spinal cord. In addition, the change of growth associated protein 43 (GAP43) level in the spinal cord was assessed by Western blot. Our data showed that chronic treatment with A-438079 increased MWT and decreased TWD on days 11-21 post-SNI while decreased depression-like and anxiety-like behaviors. A-438079 administration significantly attenuated the elevated immunoreactivities of IBA-1 and GFAP in microglia and astrocytes after SNI. Furthermore, the decreased expression of GAP-43 in the spinal cord due to SNI was significantly attenuated by A-438079. However, when A-438079 and a pharmacological agonist (BzATP) of P2X7R were given simultaneously, all the effects caused by A-438079 alone were reversed. In brief, our study revealed the protective role of inhibiting P2X7R in the amygdala against symptoms associated with NP, possibly attributing to its inhibitory effects on spinal microglia and astrocytes.

Effects of venlafaxine on the expression level and methylation status of genes involved in oxidative stress in rats exposed to a chronic mild stress

Recent human and animal studies indicate that oxidative and nitrosative stress may play a role in the aetiology and pathogenesis of depression. This study investigates the effect of chronic administration of the serotonin‐norepinephrine reuptake inhibitor, venlafaxine, on the expression and methylation status of SOD1, SOD2, GPx1, GPx4, CAT, NOS1 and NOS2 in the brain and blood of rats exposed to a chronic mild stress (CMS) model of depression. Separate groups of animals were exposed to CMS for 2 or 7 weeks; the second group received saline or venlafaxine (10 mg/kg/d, IP) for 5 weeks. After completion of both stress conditions and drug administration, the mRNA and protein expression of selected genes and the methylation status of their promoters were measured in peripheral mononuclear blood cells (PBMCs) and in brain structures (hippocampus, amygdala, hypothalamus, midbrain, cortex, basal ganglia) with the use of TaqMan Gene Expression Assay, Western blot and methylation‐sensitive high‐resolution melting techniques. CMS caused a decrease in sucrose consumption, and this effect was normalized by fluoxetine. In PBMCs, SOD1, SOD2 and NOS2 mRNA expression changed only after venlafaxine administration. In brain, CAT, Gpx1, Gpx4 and NOS1 gene expression changed following CMS or venlafaxine exposure, most prominently in the hippocampus, midbrain and basal ganglia. CMS increased the methylation of the Gpx1 promoter in PBMCs, the second Gpx4 promoter in midbrain and basal ganglia, and SOD1 and SOD2 in hippocampus. The CMS animals treated with venlafaxine displayed a significantly higher CAT level in midbrain and cerebral cortex. CMS caused an elevation of Gpx4 in the hippocampus, which was lowered in cerebral cortex by venlafaxine. The results indicate that CMS and venlafaxine administration affect the methylation of promoters of genes involved in oxidative and nitrosative stress. They also indicate that peripheral and central tissue differ in their response to stress or antidepressant treatments. It is possible that that apart from DNA methylation, a crucial role of expression level of genes may be played by other forms of epigenetic regulation, such as histone modification or microRNA interference.

These findings provide strong evidence for thesis that analysis of the level of mRNA and protein expression as well as the status of promoter methylation can help in understanding the pathomechanisms of mental diseases, including depression, and the mechanisms of action of drugs effective in their therapy.

Oleuropein Reverses Repeated Corticosterone-Induced Depressive-Like Behavior in mice: Evidence of Modulating Effect on Biogenic Amines

Depression is still one of challenging, and widely encountered disorders with complex etiology. The role of healthy diet and olive oil in ameliorating depression has been claimed. This study was designed to explore the effects of oleuropein; the main constituent of olive oil; on depression-like behaviors that are induced by repeated administration of corticosterone (40 mg/kg, i.p.), once a day for 21 days, in mice. Oleuropein (8, 16, and 32 mg/kg, i.p.) or fluoxetine (20 mg/kg, positive control, i.p.1) was administered 30 minutes prior to corticosterone injection. Sucrose consumption test, open-field test (OFT), tail suspension test (TST), and forced swimming test (FST) were performed. Reduced Glutathione (GSH), lipid peroxidation, and biogenic amines; serotonin, dopamine, and nor-epinephrine; levels were also analyzed in brain homogenates. Corticosterone treatment induced depression-like behaviors, it increased immobility time in the TST, OFT, and FST, decreased the number of movements in OFT, and decreased sucrose consumption. Corticosterone effect was associated with depletion of reduced glutathione and increase of lipid peroxidation, in addition to modification of biogenic amines; decreased serotonin and dopamine. Oleuropein or fluoxetine administration counteracted corticosterone-induced changes. In conclusion, oleuropein showed a promising antidepressant activity, that is evident by improving corticosterone-induced depression-like behaviors, and normalizing levels of biogenic amines.

High-refined carbohydrate diet consumption induces neuroinflammation and anxiety-like behavior in mice

Consumption of poor nutrients diets is associated with fat tissue expansion and with a central and peripheral low-grade inflammation. In this sense, the microglial cells in the central nervous system are activated and release pro-inflammatory cytokines that up-regulate the inducible nitric oxide synthase (iNOS), promoting Nitric Oxide (NO) production. The excess of NO has been proposed to facilitate anxious states in humans and rodents. We evaluated whether consumption of a high-refined carbohydrate-containing diet (HC) in mice induced anxiety-like behavior in the Novelty Suppressed Feeding Test (NFST) trough facilitation of NO, in the prefrontal cortex (PFC) and hippocampus (HIP). We also verified if HC diet induces activation of microglial cells, alterations in cytokine and leptin levels in such regions. Male BALB/c mice received a standard diet or a HC diet for 3 days or 12 weeks. The chronic consumption of HC diet, but not acute, induced an anxiogenic-like effect in the NSF test and an increase in the nitrite levels in the PFC and HIP. The preferential iNOS inhibitor, aminoguanidine (50 mg/kg, i.p.), attenuated such effects. Moreover, microglial cells in the HIP and PFC were activated after chronic consumption of HC diet. Finally, the expression of iNOS in the PFC and TNF, IL6 and leptin levels in HIP were higher in chronically HC fed mice. Taken together, our data reinforce the notion that diets containing high-refined carbohydrate facilitate anxiety-like behavior, mainly after a long period of consumption. The mechanisms involve, at least in part, the augmentation of neuroinflammatory processes in brain areas responsible for anxiety control.

Behavioural characterisation of chronic unpredictable stress based on ethologically relevant paradigms in rats

The chronic unpredictable stress (CUS) paradigm is extensively used in preclinical research. However, CUS exhibits translational inconsistencies, some of them resulting from the use of adult rodents, despite the evidence that vulnerability for many psychiatric disorders accumulates during early life. Here, we assessed the validity of the CUS model by including ethologically-relevant paradigms in juvenile rats. Thus, socially-isolated (SI) rats were submitted to CUS and compared with SI (experiment 1) and group-housed controls (experiment 1 and 2). We found that lower body-weight gain and hyperlocomotion, instead of sucrose consumption and preference, were the best parameters to monitor the progression of CUS, which also affected gene expression and neurotransmitter contents associated with that CUS-related phenotype. The behavioural characterisation after CUS placed locomotion and exploratory activity as the best stress predictors. By employing the exploratory factor analysis, we reduced each behavioural paradigm to few latent variables which clustered into two general domains that strongly predicted the CUS condition: (1) hyper-responsivity to novelty and mild threats, and (2) anxiety/depressive-like response. Altogether, the analyses of observable and latent variables indicate that early-life stress impairs the arousal-inhibition system leading to augmented and persistent responses towards novel, rewarding, and mildly-threatening stimuli, accompanied by lower body-weight gain.

β-asarone relieves chronic unpredictable mild stress induced depression by regulating the extracellular signal-regulated kinase signaling pathway

The present study aimed to investigate the effect of β-asarone treatment in a rat model of depression induced by chronic unpredictable mild stress (CUMS) and to further explore the underlying molecular mechanisms. A rat model of depression was established by subjecting rat to CUMS and treated with various concentrations of β-asarone (12.5, 25 and 50 mg/kg/day) and fluoxetine (20 mg/kg/day). Next, behavioral tests, including an open field, sucrose preference and forced swimming tests, were performed. In addition, the apoptosis of hippocampal neuronal cells was determined by flow cytometry, gene expression levels were detected by reverse transcription-quantitative polymerase chain reaction and protein levels were determined by western blot assay. The results revealed that β-asarone significantly mitigated CUMS-induced depression-like behavior, evidenced by the increased sucrose intake, crossing and rearing numbers, and decreased immobility time in the forced swimming test. Furthermore, β-asarone significantly decreased the apoptosis rate of hippocampal neuronal cells in rats subjected to CUMS. β-asarone was also found to enhance CREB, BDNF, Trk-B and Bcl-2 levels, and reduce Bad level in the hippocampus of CUMS-treated rats. In addition, the activation of extracellular signal-regulated kinase pathway inhibited by CUMS was promoted by β-asarone treatment. In conclusion, the present study findings indicated the antidepressant-like effects of β-asarone on CUMS-induced depression in rats.

Involvement of the nitric oxide pathway in the anti-depressant-like effects of thalidomide in mice

BACKGROUND

Thalidomide is a sedative/hypnotic agent that is currently used to treat patients suffering from multiple myeloma, myelodysplastic syndromes and erythema nodosum leprosum. Although previous studies have demonstrated that thalidomide possesses anti-depressant-like properties, the exact mechanism that thalidomide exerts this effect is not understood. In this study, we used two mouse models of depression and investigated the possible role of nitric oxide (NO), NO synthase (NOS) and inducible NOS (iNOS) in the ant-depressant-like effects of thalidomide.

METHODS

Male mice were injected with different doses of thalidomide intraperitoneally. In order to assess the anti-depressant-like properties of thalidomide, the immobility time of mice was assessed in the forced swimming test (FST) and tail suspension test (TST). Locomotor activity was assessed using the open-field test. To assess the role of nitric oxide, N(G)-nitro-L-arginine methyl ester (L-NAME, non-specific NOS inhibitor), aminoguanidine (selective iNOS inhibitor) or L-arginine (NO precursor) were administered intraperitoneally along with specific doses of thalidomide.

RESULTS

Thalidomide (10 mg/kg) significantly reduced immobility time in FST and TST. Aminoguanidine (50 mg/kg) and L-NAME (10 mg/kg) significantly augmented the anti-immobility effects of thalidomide (5 mg/kg). L-arginine (750 mg/kg) significantly inhibited the anti-immobility effects of thalidomide (10 mg/kg). None of the treatment groups demonstrated alteration of locomotor activity.

CONCLUSION

Thalidomide exerts its anti-depressant-like effects through a mechanism dependent upon NO inhibition.

Nitric oxide: Antidepressant mechanisms and inflammation

Millions of individuals worldwide suffers from mood disorders, especially major depressive disorder (MDD), which has a high rate of disease burden in society. Although targeting the biogenic amines including serotonin, and norepinephrine have provided invaluable links with the pharmacological treatment of MDD over the last four decades, a growing body of evidence suggest that other biologic systems could contribute to the pathophysiology and treatment of MDD. In this chapter, we highlight the potential role of nitric oxide (NO) signaling in the pathophysiology and thereby treatment of MDD. This has been investigated over the last four decades by showing that (i) levels of NO are altered in patients with major depression; (ii) modulators of NO signaling exert antidepressant effects in patients with MDD or in the animal studies; (iii) NO signaling could be targeted by a variety of antidepressants in animal models of depression; and (iv) NO signaling can potentially modulate the inflammatory pathways that underlie the pathophysiology of MDD. These findings, which hypothesize an NO involvement in MDD, can provide a new insight into novel therapeutic approaches for patients with MDD in the future.

Mice lacking Casp1, Ifngr and Nos2 genes exhibit altered depressive- and anxiety-like behaviour, and gut microbiome composition

Converging evidence supports the involvement of pro-inflammatory pathways and the gut microbiome in major depressive disorder (MDD). Pre-clinical and clinical studies suggest that decreasing pro-inflammatory signaling may provide clinical benefit in MDD. In this study, we used the chronic unpredictable stress (CUS) paradigm to assess whether mice lacking the pro-inflammatory caspase 1, interferon gamma-receptor, and nitric oxide synthase (Casp1, Ifngr, Nos2)-/- present altered depressive- and anxiety-like behaviour at baseline and in response to CUS. In comparison to wild-type (wt) mice, (Casp1, Ifngr, Nos2)-/- mice displayed decreased depressive- and anxiety-like behaviour, and increased hedonic-like behaviour and locomotor activity at baseline, and resistance to developing anhedonic-like behaviour and a heightened emotional state following stress. Plasma levels of ACTH and CORT did not differ between the triple knockout and wt mice following stress. The faecal microbiome of (Casp1, Ifngr, Nos2)-/- mice differed from that of wt mice at baseline and displayed reduced changes in response to chronic stress. Our results demonstrate that simultaneous deficit in multiple pro-inflammatory pathways has antidepressant-like effects at baseline, and confers resilience to stress-induced anhedonic-like behaviour. Moreover, accompanying changes in the gut microbiome composition suggest that CASP1, IFNGR and NOS2 play a role in maintaining microbiome homeostasis.

Helicid Ameliorates Learning and Cognitive Ability and Activities cAMP/PKA/CREB Signaling in Chronic Unpredictable Mild Stress Rats

Helicid (4-formylphenyl-O-β-D-allopyranoside), an active component found in seeds from the Chinese herb Helicia nilagirica, has been reported to exert sedative, analgesic, hypnotic and antidepressant effects. The present study was designed to evaluate the antidepressant, learning and cognitive improvement effects of helicid in a chronic unpredictable mild stress (CUMS) model of depression in rats and to explore cAMP/protein kinase A (PKA)/cAMP response element-binding (CREB) signaling pathway. Sprague-Dawley rats were randomly assigned to six groups (n = 10): control; CUMS; CUMS + fluoxetine (5 mg/kg) and CUMS + helicid at 8, 16 and 32 mg/kg. All rats were subjected to 12 weeks of CUMS protocols and drug administration during the last 6 weeks of CUMS. Our results showed that helicid, at a dose of 32 mg/kg, significantly reversed decreases in body weight and sucrose consumption, increased the distance and number of crossings in the open-field test (OFT), reduced immobility times in the forced swimming test (FST) and improved spatial memory in the Morris water maze (MWM); all of these effects had been induced by CUMS paradigm. Immunohistochemistry showed that administration of helicid could promoted the proliferation of neurons in the hippocampal CA1 and dentate gyrus (DG) regions. CUMS rats treated with helicid had dramatically decreased protein levels of serotonin transporters (SERTs). In addition, CUMS resulted in a significant reduction in the expression of cAMP, PKA C-α and p-CREB, each of which were partially attenuated by helicid administration. These results indicated that helicid could improve depressive behaviors, learning and cognitive deficits and increase hippocampal neurogenesis, which may be mediated by the regulation of SERTs, activation of the cAMP/PKA/CREB signaling pathway and upregulation of p-CREB levels in hippocampal.

Adolescent environmental enrichment prevents behavioral and physiological sequelae of adolescent chronic stress in female (but not male) rats

The late adolescent period is characterized by marked neurodevelopmental and endocrine fluctuations in the transition to early adulthood. Adolescents are highly responsive to the external environment, which enhances their ability to adapt and recover from challenges when given nurturing influences, but also makes them vulnerable to aberrant development when exposed to prolonged adverse situations. Female rats are particularly sensitive to the effects of chronic stress in adolescence, which manifests as passive coping strategies and blunted hypothalamo-pituitary adrenocortical (HPA) stress responses in adulthood. We sought to intervene by exposing adolescent rats to environmental enrichment (EE) immediately prior to and during chronic stress, hypothesizing that EE would minimize or prevent the long-term effects of stress that emerge in adult females. To test this, we exposed male and female rats to EE on postnatal days (PND) 33-60 and implemented chronic variable stress (CVS) on PND 40-60. CVS consisted of twice-daily unpredictable stressors. Experimental groups included: CVS/unenriched, unstressed/EE, CVS/EE and unstressed/unenriched (n = 10 of each sex/group). In adulthood, we measured behavior in the open field test and forced swim test (FST) and collected blood samples following the FST. We found that environmental enrichment given during the adolescent period prevented the chronic stress-induced transition to passive coping in the FST and reversed decreases in peak adrenocortical responsiveness observed in adult females. Adolescent enrichment had little to no effect on males or unstressed females tested in adulthood, indicating that beneficial effects are specific to females that were exposed to chronic stress.

A high-refined carbohydrate diet facilitates compulsive-like behavior in mice through the nitric oxide pathway

Obesity is characterized by abnormal adipose tissue expansion and is associated with chronic inflammation. Obesity itself may induce several comorbidities, including psychiatric disorders. It has been previously demonstrated that proinflammatory cytokines are able to up-regulate inducible nitric oxide synthase (iNOS) and nitric oxide (NO) release, which both have a role in compulsive related behaviors.

OBJECTIVE

To evaluate whether acute or chronic consumption of a high-refined carbohydrate-containing (HC) diet will modify burying-behavior in the Marble Burying Test (MBT) through augmentation of NO signaling in the striatum, a brain region related to the reward system. Further, we also verified the effects of chronic consumption of a HC diet on the reinforcing effects induced by cocaine in the Conditioned Place Preference (CPP) test.

METHODS

Male BALB/c mice received a standard diet (control diet) or a HC diet for 3 days or 12 weeks.

RESULTS

An increase in burying behavior occurred in the MBT after chronic consumption of a HC diet that was associated with an increase of nitrite levels in the striatum. The pre-treatment with Aminoguanidine (50 mg/kg), a preferential inhibitor of iNOS, prevented such alterations. Additionally, a chronic HC diet also induced a higher expression of iNOS in this region and higher glutamate release from striatal synaptosomes. Neither statistical differences were observed in the expression levels of the neuronal isoform of NOS nor in microglia number and activation. Finally, the reinforcing effects induced by cocaine (15 mg/kg, i.p.) during the expression of the conditioned response in the CPP test were not different between the chronically HC diet fed mice and the control group. However, HC diet-feeding mice presented impairment of cocaine-preference extinction.

CONCLUSION

Altogether, our results suggest that the chronic consumption of a HC diet induces compulsive-like behavior through a mechanism possibly associated with NO activation in the striatum.

Influence of citicoline on citalopram-induced antidepressant activity in depressive-like symptoms in male mice

Depression is associated with significant functional disabilities. Application of new drugs which could enhance the effectiveness of antidepressants drug and reduce side effects of their long-term use seems necessary. Citicoline is used as an effective chemical agent for improving the symptoms of some neurodegenerative diseases. Therefore, in this survey, the application of citicoline as an adjuvant drug was evaluated in mice model of depression. A total of 180 adult NMRI male albino mice were used in this study. All groups were exposed to chronic unexpected mild stress (CUMS) followed by treatment with various doses of citalopram or/and citicoline or saline for 21 days. Sucrose preference (SP), open field (OF), and forced swimming test (FST) were applied to evaluate depression symptoms in the groups. The results indicated that only citicoline at the 5 mg/kg dose had shifted its status from being noneffective to become significantly effective in the co-administered group. The means of SP, OFT, and FST of the treatment groups were significantly different in favor of co-administered group compared with the other groups as well as the control group. Based on the results, it can be concluded that administration of citicoline, as an adjuvant drug, in combination with citalopram, enhanced the effectiveness of selective serotonin reuptake inhibitors (SSRI) drugs for depression treatment.

Pathologic role of nitrergic neurotransmission in mood disorders

Mood disorders are chronic, recurrent mental diseases that affect millions of individuals worldwide. Although over the past 40 years the biogenic amine models have provided meaningful links with the clinical phenomena of, and the pharmacological treatments currently employed in, mood disorders, there is still a need to examine the contribution of other systems to the neurobiology and treatment of mood disorders. This article reviews the current literature describing the potential role of nitric oxide (NO) signaling in the pathophysiology and thereby the treatment of mood disorders. The hypothesis has arisen from several observations including (i) altered NO levels in patients with mood disorders; (ii) antidepressant effects of NO signaling blockers in both clinical and pre-clinical studies; (iii) interaction between conventional antidepressants/mood stabilizers and NO signaling modulators in several biochemical and behavioral studies; (iv) biochemical and physiological evidence of interaction between monoaminergic (serotonin, noradrenaline, and dopamine) system and NO signaling; (v) interaction between neurotrophic factors and NO signaling in mood regulation and neuroprotection; and finally (vi) a crucial role for NO signaling in the inflammatory processes involved in pathophysiology of mood disorders. These accumulating lines of evidence have provided a new insight into novel approaches for the treatment of mood disorders.

Involvement of NO/NMDA-R pathway in the behavioral despair induced by amphetamine withdrawal

Abrupt discontinuation of chronic amphetamine consumption leads to withdrawal symptoms including depression, anhedonia, dysphoria, fatigue, and anxiety. These irritating symptoms may result in continuing to take the drug or can lead to suicidal behavior. Past studies have shown the involvement of various biologic systems in depression induced following amphetamine withdrawal (AW). However, there is no evidence about the relation between nitric oxide (NO) with NMDA receptors on depression following AW. In this study, we examined the involvement of the NO/NMDA pathways on depressive-like behaviors after 24 h withdrawal following 5 continuous days of amphetamine administration in male NMRI mice. Behavioral tasks used for depression assessment included the forced swimming test (FST), the Splash test and the open field test (OFT). In order to evaluate the role of NO/NMDA pathways animals treated with MK-801 (NMDA-R antagonist), Aminoguanidine (AG), a selective iNOS inhibitor, Nω-Nitro-l-arginine (L-NNA), a non-selective NOS inhibitor and 7-Nitro indazole (7-NI), a selective nNOS inhibitor. We also measured the level of nitrite in the hippocampus. Our data showed that AW induced the depressive-like effect in the FST and the Splash test. We showed that administration of AG, L-NNA, and MK-801 mitigated AW induced depression, however, 7-NI was failed to decrease depressive-like behaviors. Also, the antidepressant-like effect of co-injection of sub-effective doses of MK-801 with AG suggested that inducible nitric oxide synthase (iNOS) is associated with NMDA-R in AW induced depression. In conclusion, both NO and NMDA-R pathways are involved and related to each other in depression induced following AW.

The molecular aspects of oxidative & nitrosative stress and the tryptophan catabolites pathway (TRYCATs) as potential causes of depression

Depression is the most common mental disorder in the world. It is estimated that 350 million people suffer from depression worldwide. Depressive disorders will have become the second most frequent health problem globally by the year 2020, just behind ischemic heart disease. The causes of depressive disorders are not fully known. Previous studies showed that impaired tryptophan catabolites pathway, oxidative and nitrosative stress may play an important role in the pathogenesis of depression. Patients with depression have lower plasma levels of superoxide dismutase and glutathione peroxidise in comparison to controls. Moreover, depressed patients are characterized by decreased plasma levels of zinc, coenzyme Q10, albumin, uric acid, vitamin E and glutathione. Abnormal nitric oxidative production and nitric oxide synthase activity are also associated with depression. A dysfunction of the tryptophan catabolites pathway, indicated by increased levels of tryptophan 2,3-dioxygenase and indoleamine 2,3-dioxygenase, is also involved in the development of depression. Furthermore, increased levels of kynurenine and quinolinic acid might cause depression. Moreover, studies to date indicate that 8-oxyguanine, malondialdehyde, and 8-iso-prostaglandin F2α may serve as possible biomarkers. Additionally, regulation of defective mechanisms may provide a promising direction for the development of new and effective therapies.

2, 3, 5, 4'-Tetrahydroxystilbene-2-O-β-D-glucoside prevention of lipopolysaccharide-induced depressive-like behaviors in mice involves neuroinflammation and oxido-nitrosative stress inhibition

Although numerous hypotheses have been raised in recent years, the exact mechanisms that promote the development of major depression are largely unknown. Recently, strategies targeting the process of neuroinflammation and oxidative stress in depression have been attracting greater attention. 2, 3, 5, 4'-Tetrahydroxystilbene-2-O-β-D-glucoside (TSG), a compound purified from a traditional Chinese herbal medicine polygonummultiflorum, has been widely reported to inhibit neuroinflammation and oxidative stress. In this context, we investigated whether TSG affects lipopolysaccharide (LPS)-induced depressive-like behaviors in a manner associated with neuroinflammation and oxido-nitrosative stress. Results showed that administration of ICR mice with 0.83 mg/kg of LPS-induced typical depressive-like behaviors in the experiments of the tail-suspension test, the forced-swimming test, and sucrose preference, and these behaviors were prevented by TSG treatment (30 and 60 mg/kg). Further analysis showed that TSG pretreatment at the doses of 30 and 60 mg/kg not only inhibited the production of proinflammatory cytokines induced by LPS, such as interleukin-1β, interleukin-6, and tumor necrosis factor-α, but also prevented the LPS-induced enhancement of oxido-nitrosative stress in mouse hippocampus and prefrontal cortex. The LPS-induced decreases in brain-derived neurotrophic factor levels in the hippocampus and prefrontal cortex were also prevented by TSG treatment. Generally, our data provide evidence to show that TSG could be used to cope with depressive-like symptoms by inhibition of neuroinflammation and oxido-nitrosative stress.

Brain antioxidant effect of mirtazapine and reversal of sedation by its combination with alpha-lipoic acid in a model of depression induced by corticosterone

BACKGROUND

Depression is accompanied by activated neuro-oxidative and neuro-nitrosative pathways, while targeting these pathways has clinical efficacy in depression. This study aimed to investigate the effects of mirtazapine (MIRT) alone and combined with alpha-lipoic acid (ALA) against corticosterone (CORT) induced behavioral and oxidative alterations.

METHODS

Male mice received vehicle or CORT 20mg/kg during 14 days. From the 15th to 21st days they were divided in groups administered: vehicle, MIRT 3mg/kg or the combinations MIRT+ALA100 or MIRT+ALA200. On the 21st day of treatment, the animals were subjected to behavioral tests. Twenty-four hours after the last drug administration hippocampus (HC) and striatum (ST) were dissected for the determination reduced glutathione (GSH), lipid peroxidation (LP) and nitrite levels.

RESULTS

CORT induced anxiety- and depressive-like behaviors as observed by increased immobility time in the tail suspension test and decreased sucrose consumption. MIRT or MIRT+ALA are effective in reversing anxiety- and depressive-like behaviors induced by CORT. CORT and MIRT alone prolonged sleeping time and this effect was reversed by MIRT+ALA. CORT significantly increased LP, which was reversed by MIRT or MIRT+ALA. Nitrite levels were increased in CORT-treated animals and reversed by MIRT+ALA200 (HC), MIRT or MIRT+ALA (ST).

LIMITATION

A relative small sample size and lack of a washout period between drug administration and behavioral testing.

CONCLUSIONS

MIRT or MIRT+ALA reverse CORT-induced anxiety- and depressive-like behaviors probably via their central antioxidant effects. Augmentation of MIRT with ALA may reverse sedation, an important side effect of MIRT. Randomized controlled studies are needed to examine the clinical efficacy of this combination in human depression.

Huanglian-Jie-Du-Tang Extract Ameliorates Depression-Like Behaviors through BDNF-TrkB-CREB Pathway in Rats with Chronic Unpredictable Stress

Neuroinflammation is considered as one of the common pathogeneses of depression. Huanglian-Jie-Du-Tang (HJDT) is a traditional Chinese herbal formula. The present study investigates the antidepressant-like effect of HJDT and its possible mechanism in rats. Rats were given HJDT (2, 4, and 8 g/kg, intragastrically), paroxetine (1.8 mg/kg, intragastrically), or an equivalent volume of saline for 42 days. The depression-related behaviors, including sucrose preference test (SPT), open field test (OFT), novel objective recognition task (NORT), and forced swimming test (FST), were detected. 5-Hydroxytryptamine (5-HT) and dopamine (DA) contents, microglial activation, proinflammatory cytokines, and brain derived neurotrophic factor (BDNF), tropomyosin receptor kinases B (TrkB), and cAMP-responsive element binding protein (CREB) expression were investigated. The results indicated HJDT (2 and 4 g/kg) dramatically ameliorated the depression-like behaviors. Also HJDT decreased the number of microglia and the proinflammatory cytokines in hippocampus. Western-blotting analysis displayed HJDT upregulated BDNF, TrkB, and pCREB/CREB expression in hippocampus. Particularly, pCREB DNA activity enhanced with HJDT treatment in hippocampus. But there was no difference in the 5-HT and DA contents with HJDT treatment. In conclusion, it was supposed that HJDT might be a potential Chinese medicine decoction for treating or alleviating complex symptoms of depression through BDNF-TrkB-CREB pathway.

Baicalin ameliorates chronic unpredictable mild stress-induced depressive behavior: Involving the inhibition of NLRP3 inflammasome activation in rat prefrontal cortex

Abnormal activation of nucleotide-binding domain, leucine-rich repeat, pyrin domain containing protein 3 (NLRP3) inflammasome could induce inflammation in the central nervous system and result in the hyperactivity of HPA axis, which were involved in the pathophysiology of depression. Baicalin, a major polyphenol compound extracts from Scutellaria radix roots, has been previously confirmed to normalize the hyperactivity of HPA axis in rats received chronic mild stress. However, its antidepressant effects and mechanisms are remains unclear in chronic unpredictable mild stress (CUMS) model of depression. In this study, CUMS treated rats showed a notable depressive-like behavior (decreased sucrose intake and locomotor activity, and increased immobility time), and significant increase in the activation of NLRP3 inflammasome and the levels of pro-inflammatory cytokines (IL-1β and IL-6) in rat prefrontal cortex. Treatment with baicalin (20, 40mg/kg) significantly reversed these changes. The present study confirmed that baicalin has antidepressant effect and its mechanisms likely related to the inhibition of NLRP3 inflammasome activation in rat prefrontal cortex.

Psychosocial stress inhibits additional stress-induced hyperexpression of NO synthases and IL-1β in brain structures

BACKGROUND

The aim of this study was to compare the expression of interleukin-1β (IL-1β), neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS) in the prefrontal cortex (PFC), hippocampus (HIP) and hypothalamus (HT) during chronic crowding (CS) (psychosocial) and restraint (RS) (physico-psychological) stress. Adaptational changes of these stress mediators to a subsequent acute RS, in two models of chronic stress were investigated.

METHODS

Rats were crowded (24 in one cage) or restrained in metal tubes for 10min twice a day for 3, 7, and 14 consecutive days and decapitated. For determination of adaptational changes the chronically crowded and restrained rats 24h after the last stress session were subjected to a single 10min RS. The IL-1β, nNOS and iNOS protein levels in brain structures samples were analyzed by Western blot procedure.

RESULTS

Chronic CS for 3days did not markedly change the subsequent acute stress induced expression of nNOS, iNOS and IL-1β protein level in PFC and iNOS protein level in HT. CS markedly decreased the expression of nNOS, iNOS and IL-1β in HIP. By contrast, parallel chronic RS, significantly increased the subsequent acute stress-induced expression of iNOS and IL-1β in PFC and considerably increased iNOS level in HT.

CONCLUSION

Chronic psychosocial stress, may protect against possible harmful action of hyperproduction of iNOS and iNOS derived nitric oxide (NO) mainly in PFC and HIP. By contrast, chronic physico-psychosocial stress may strongly potentiate additional stress-induced harmful effects of NOS and IL-1β hyperproduction.

Behavioral despair associated with a mouse model of Crohn's disease: Role of nitric oxide pathway

Crohn's disease (CD) is associated with increased psychiatric co-morbidities. Nitric oxide (NO) is implicated in inflammation and tissue injury in CD, and it may also play a central role in pathogenesis of the accompanying behavioral despair. This study investigated the role of the NO pathway in behavioral despair associated with a mouse model of CD. Colitis was induced by intrarectal (i.r.) injection of 2,4,6-trinitrobenzenesulfonic acid (10mg TNBS in 50% ethanol). Forced swimming test (FST), pharmacological studies and tissues collection were performed 72 h following TNBS administration. To address a possible inflammatory origin for the behavioral despair following colitis induction, tumor necrosis factor-alpha (TNF-α) level was measured in both the hippocampal and colonic tissue samples. In parallel, hippocampal inducible nitric oxide synthase (iNOS) and nitrite level were evaluated. Pharmacological studies targeting the NO pathway were performed 30-60 min before behavioral test. Colitis was confirmed by increased colonic TNF-α level and microscopic score. Colitic mice demonstrated a significantly higher immobility time in the FST associated to a significant increase of hippocampal TNF-α, iNOS expression and nitrite content. Acute NOS inhibition using either Nω-nitro-l-arginine methyl ester (a non-specific NOS inhibitor) or aminoguanidine hydrochloride (a specific iNOS inhibitor) decreased the immobility time in colitic groups. Moreover, acute treatment with both NOS inhibitors decreased the TNF-α level and nitrite content in the hippocampal samples. This study suggests that the NO pathway may be involved in the behavioral effects in the mouse TNBS model of CD. These findings endow new insights into the gut-brain communication during the development of colonic inflammation, which may ultimately lead to improved therapeutic strategies to combat behavior changes associated with gastrointestinal disorders.

Exploring Female Mice Interstrain Differences Relevant for Models of Depression

Depression is an extremely heterogeneous disorder. Diverse molecular mechanisms have been suggested to underlie its etiology. To understand the molecular mechanisms responsible for this complex disorder, researchers have been using animal models extensively, namely mice from various genetic backgrounds and harboring distinct genetic modifications. The use of numerous mouse models has contributed to enrich our knowledge on depression. However, accumulating data also revealed that the intrinsic characteristics of each mouse strain might influence the experimental outcomes, which may justify some conflicting evidence reported in the literature. To further understand the impact of the genetic background, we performed a multimodal comparative study encompassing the most relevant parameters commonly addressed in depression, in three of the most widely used mouse strains: Balb/c, C57BL/6, and CD-1. Moreover, female mice were selected for this study taken into account the higher prevalence of depression in women and the fewer animal studies using this gender. Our results show that Balb/c mice have a more pronounced anxious-like behavior than CD-1 and C57BL/6 mice, whereas C57BL/6 animals present the strongest depressive-like trait. Furthermore, C57BL/6 mice display the highest rate of proliferating cells and brain-derived neurotrophic factor (Bdnf) expression levels in the hippocampus, while hippocampal dentate granular neurons of Balb/c mice show smaller dendritic lengths and fewer ramifications. Of notice, the expression levels of inducible nitric oxide synthase (iNos) predict 39.5% of the depressive-like behavior index, which suggests a key role of hippocampal iNOS in depression. Overall, this study reveals important interstrain differences in several behavioral dimensions and molecular and cellular parameters that should be considered when preparing and analyzing experiments addressing depression using mouse models. It further contributes to the literature by revealing the predictive value of hippocampal iNos expression levels in depressive-like behavior, irrespectively of the mouse strain.