2D-gel based proteomics unravels neurogenesis and energetic metabolism dysfunction of the olfactory bulb in CUMS rat model

Deficit of neuronal EAAT2 impairs hippocampus CA3 neuron's activity and may induce depressive like behaviors

INTRODUCTION

Major depressive disorder (MDD) is a severe neuropsychiatric disease that is accompanied by hippocampal dysfunction. Currently, the complex neuronal types and molecules involved in the various hippocampal subfields in patients with depression remain unclear.

OBJECTIVES

We focused on the role of hippocampal excitatory amino acid transporter 2 (EAAT2) in chronic stress.

METHODS

We studied two chronic stress models, the chronic unpredictable mild stress (CUMS) and the chronic social defeat stress (CSDS) models, and performed pharmacological inhibition, genetic manipulations to examine overexpression of neuron-specific solute carrier family 1 member 2 (SLC1A2), the gene encoding EAAT2, in the dorsal CA3 and conditional Slc1a2 knockout in CA3, whole-cell recording, and behavioral tests.

RESULTS

Our results indicated that decreased EAAT2 expression and specific inhibition were associated with depression-like behavior and enhanced CA3 pyramidal neuron activity. In addition, neuron-specific EAAT2 overexpression in the CA3 yielded antidepressant-like effects and inhibited CA3 pyramidal neuron hyperactivity, whereas conditional CA3 EAAT2 knockout showed opposite effects at both behavioral and functional levels. We also found that the single-nucleotide polymorphism, rs77619780, in the SLCA1A2 gene was associated with lower MDD risk.

CONCLUSION

Our findings revealed that EAAT2 deficit in the CA3 induces depression-like behavior, which offers novel insight into MDD pathophysiology.

Olfactory genes affect major depression in highly educated, emotionally stable, lean women: a bridge between animal models and precision medicine

Most current approaches to establish subgroups of depressed patients for precision medicine aim to rely on biomarkers that require highly specialized assessment. Our present aim was to stratify participants of the UK Biobank cohort based on three readily measurable common independent risk factors, and to investigate depression genomics in each group to discover common and separate biological etiology. Two-step cluster analysis was run separately in males (n = 149,879) and females (n = 174,572), with neuroticism (a tendency to experience negative emotions), body fat percentage, and years spent in education as input variables. Genome-wide association analyses were implemented within each of the resulting clusters, for the lifetime occurrence of either a depressive episode or recurrent depressive disorder as the outcome. Variant-based, gene-based, gene set-based, and tissue-specific gene expression test were applied. Phenotypically distinct clusters with high genetic intercorrelations in depression genomics were found. A two-cluster solution was the best model in each sex with some differences including the less important role of neuroticism in males. In females, in case of a protective pattern of low neuroticism, low body fat percentage, and high level of education, depression was associated with pathways related to olfactory function. While also in females but in a risk pattern of high neuroticism, high body fat percentage, and less years spent in education, depression showed association with complement system genes. Our results, on one hand, indicate that alteration of olfactory pathways, that can be paralleled to the well-known rodent depression models of olfactory bulbectomy, might be a novel target towards precision psychiatry in females with less other risk factors for depression. On the other hand, our results in multi-risk females may provide a special case of immunometabolic depression.

Metformin Improves Comorbid Depressive Symptoms in Mice with Allergic Rhinitis by Reducing Olfactory Bulb Damage

Allergic rhinitis (AR) is a widespread disease that is frequently comorbid with depression. However, the mechanisms and treatments for depression in AR remain underexplored. Metformin, a widely used antidiabetic drug, has shown antidepressant effects. The aim of this study was to explore the effects and potential mechanisms of metformin on depression-like behaviors in an AR mouse model. In the present study, mice were sensitized and challenged with ovalbumin (OVA) to induce AR. Results showed that mice with AR exhibited significant depression-like behavior which was attenuated by metformin. In addition, the levels of expression of synaptic plasticity markers (anti-microtubule-associated protein 2, synaptophysin, postsynaptic density protein 95), neurogenesis markers (doublecortin and Ki-67), and brain-derived neurotrophic factor were decreased in the olfactory bulb (OB) of mice with AR, while metformin ameliorated all these alterations and reduced apoptosis in the OB of these mice. Furthermore, it enhanced the phosphorylation of AMP-activated kinase (AMPK) and the levels of ten-eleven translocation 2 (TET2) and 5-hydroxymethylcytosine in the OB. In conclusion, our findings suggest that metformin might be a viable strategy for treating AR-related depression, possibly by modulating neuroplasticity, neurogenesis, apoptosis, and BDNF signaling in the OB via the AMPK/TET2 pathway.

Upregulation of carbonic anhydrase 1 beneficial for depressive disorder

Carbonic Anhydrase 1 (CAR1) is a zinc-metalloenzyme that catalyzes the hydration of carbon dioxide, and the alteration of CAR1 has been implicated in neuropsychiatric disorders. However, the mechanism underlying the role of CAR1 in major depressive disorder (MDD) remains largely unknown. In this study, we report the decreased level of CAR1 in MDD patients and depression-like model rodents. We found that CAR1 is expressed in hippocampal astrocytes and CAR1 regulates extracellular bicarbonate concentration and pH value in the partial hilus. Ablation of the CAR1 gene increased the activity of granule cells via decreasing their miniature inhibitory postsynaptic currents (mIPSC), and caused depression-like behaviors in CAR1-knockout mice. Astrocytic CAR1 expression rescued the deficits in mIPSCs of granule cells and reduced depression-like behaviors in CAR1 deficient mice. Furthermore, pharmacological activation of CAR1 and overexpression of CAR1 in the ventral hippocampus of mice improved depressive behaviors. These findings uncover a critical role of CAR1 in the MDD pathogenesis and its therapeutic potential.

A novel insight for high-rate and low-efficiency glucose metabolism in depression through stable isotope-resolved metabolomics in CUMS-induced rats

BACKGROUND

Existing research has suggested that depression results in disorders of glucose metabolism in the organism which causing insufficient energy supply. However, the overall changes in glucose metabolism that arise from depression have not been clarified.

METHODS

In this study, the depression-like behavior in chronically unpredictable mild stressed rats was investigated, and the fate of glucose was tracked through isotope tracing and mass spectrometry, with a focus on metabolite changes in cecal contents.

RESULTS

As indicated by the results, the isotopic results of cecal contents can indicate the metabolic end of the organism. Moreover, the TCA cycle activity was notably reduced, and the gluconeogenesis pathway was abnormally up-regulated in the CUMS-induced rats. The organism expedited other glucose metabolism pathways to make up for the insufficiency of energy. As a result, the activity of the inefficient glycolysis pathway was increased.

LIMITATIONS

Existing research has only investigated the metabolism of 13C-glucose, and lipids and proteins have been rarely explored.

CONCLUSIONS

The chronic unpredictable mild stress can inhibit the entry of pyruvate into mitochondria in SD rats, such that the activity of TCA is reduced, and insufficient energy supply is caused. The organism is capable of expediting other glucose metabolism rate pathways to make up for the insufficiency of energy, whereas it still cannot compensate for the loss of energy. As a result, CUMS-induced rats exhibited high-rate and low-efficiency glucose metabolism.

Tryptophan-5-HT pathway disorder was uncovered in the olfactory bulb of a depression mice model by metabolomic analysis

Major depression (MD) is a severe mental illness that creates a heavy social burden, and the potential molecular mechanisms remain largely unknown. Lots of research demonstrate that the olfactory bulb is associated with MD. Recently, gas chromatography-mass spectrometry-based metabolomic studies on depressive rats indicated that metabolisms of purine and lipids were disordered in the olfactory bulb. With various physicochemical properties and extensive concentration ranges, a single analytical technique could not completely cover all metabolites, hence it is necessary to adopt another metabolomic technique to seek new biomarkers or molecular mechanisms for depression. Therefore, we adopted a liquid chromatography-mass spectrometry metabonomic technique in the chronic mild stress (CMS) model to investigate significant metabolic changes in the olfactory bulb of the mice. We discovered and identified 16 differential metabolites in the olfactory bulb of the CMS treatments. Metabolic pathway analysis by MetaboAnalyst 5.0 was generated according to the differential metabolites, which indicated that the tryptophan metabolism pathway was the core pathogenesis in the olfactory bulb of the CMS depression model. Further, the expressions of tryptophan hydroxylase (TpH) and aromatic amino acid decarboxylase (AAAD) were detected by western blotting and immunofluorescence staining. The expression of TpH was increased after CMS treatment, and the level of AAAD was unaltered. These results revealed that abnormal metabolism of the tryptophan pathway in the olfactory bulb mediated the occurrence of MD.

Isobaric Tags for Relative and Absolute Quantitation Identification of Blood Proteins Relevant to Paroxetine Response in Patients With Major Depressive Disorder

OBJECTIVES

Isobaric tags for relative and absolute quantitation (iTRAQ) is a proteomic investigation that could be utilized for rapid identification and quantification of proteins, which we would use to identify differentially expressed proteins in treatment responsive patients with major depressive disorder (MDD).

METHODS

Six treatment responsive patients of MDD were recruited, and their peripheral blood mononuclear cell (PBMC) were collected before and after 4 weeks of paroxetine treatment. iTRAQ and Mascot search engine were used to detect differentially expressed proteins, which were then validated by Western blot.

RESULTS

Two thousand one hundred and fifty three proteins were screened, and seven proteins showed differences of more than two-fold and 62 proteins with a differences of less than two-fold. Six proteins with commercially available antibodies were identified, and were validated by Western blot in 10 paroxetine responsive MDD patients. Putative hydroxypyruvate isomerase (HYI), eukaryotic translation initiation factor 4H (eIF4H), and RNA binding motif 8A (RBM8A) had statistically significant differences before and after treatment in the validation. Data are available via ProteomeXchange with identifier PXD028947.

CONCLUSIONS

By using iTRAQ and Western blot, we were able to identify HYI, eIF4H, and RAM8a to be the potential predictors of paroxetine treatment response in patients with MDD. This finding could help establish future individualized medicine.

Comparative Proteomics of Rat Olfactory Bulb Reveal Insights into Susceptibility and Resiliency to Chronic-stress-induced Depression or Anxiety

Chronic stress causes the abnormality of olfactory bulb (OB) in both anxiety and depression, however, the unique and common neurobiological underpinnings are still poorly understood. Previously, we built the three groups by chronic mild stress (CMS), depression-susceptible (Dep-Sus): with depression-like behavior, anxiety-susceptible (Anx-Sus): with anxiety-like behavior and insusceptible (Insus): without depression- and anxiety-like behaviors. To continuously explore the protein expression changes in these three groups, comparative quantitative proteomics analysis was conducted on the rat OB as crucial part of the olfactory system. Next, bioinformatics analyses were implemented whereas protein expressions were independently analyzed by parallel reaction monitoring (PRM) or Western blot (WB). The OB-proteome analysis identified totally 133 differentially expressed proteins as a CMS response. These deregulated proteins were involved in multiple functions and significant pathways potentially correlated with phenotypes of maladaptive behavior of depression or anxiety as well as adaptive behavior, and hence might act as potential candidate protein targets. The subsequent PRM-based or WB-based analyses showed that changes in Nefl, Mtmr7 and Tk2; Prkaca, Coa3, Cox6c2, Lamc1 and Tubal3; and Pabpn1, Nme3, Sos1 and Lum were uniquely associated with Dep-Sus, Anx-Sus, and Insus groups, respectively. These phenotype-specific deregulated proteins were primarily involved in multiple metabolic and signaling pathways, suggesting that the identical CMS differently impacted the olfactory protein regulation system and biological processes. To sum up, our present data as a useful proteomics underpinning provided the common and distinct molecular insights into the biochemical understanding of OB dysfunction underlying susceptibility and resiliency to chronic-stress-induced anxiety or depression.

Musk (Moschus moschiferus) Attenuates Changes in Main Olfactory Bulb of Depressed Mice: Behavioral, Biochemical, and Histopathological Evidence

BACKGROUND

Musk (Moschus moschiferus) has been described to have a significant impact on the central nervous system, as well as anticonvulsion and antidepressant effects. This study was designed to evaluate the efficacy of musk in alleviating alterations induced in olfactory bulb of depressed mice exposed to chronic stress and identify the mechanism behind it.

METHODS

Fifty male albino mice were divided into five groups (n = 10 each): control, musk, chronic unpredictable mild stress (CUMS), fluoxetine-treated, and musk-treated groups were included in this study. Behavioral changes and serum levels of corticosterone and proinflammatory cytokines included tumor necrosis factor α, interleukin 6, and oxidant/antioxidant profile were assessed at the end of the experiment. Main olfactory bulb (MOB) has been processed for histopathological examination. Gene expression of caspase-3, glial fibrillary acidic protein, and Ki67 were assessed in the MOB using quantitative real-time polymerase chain reaction.

RESULTS

The study showed that musk inhalation significantly reduced (p < 0.001) corticosterone level, immobility time, inflammatory cytokines, and oxidative stress markers in CUMS-exposed mice compared to the untreated CUMS group. Musk lessened CUMS-associated neuronal alterations in the MOB and significantly reduced apoptosis and enhanced neural cell proliferation (p < 0.001) comparable to fluoxetine. Musk significantly enhanced the level of antioxidants in the serum and significantly reduced inflammatory cytokines. The anti-inflammatory and antioxidant activity of musk and its constituents seemed to be behind its neuroprotective effect observed in this study.

CONCLUSION

Musk effectively ameliorated the chronic stress-induced behavioral, biochemical, and neuronal structural changes in MOB mostly through its antioxidant and anti-inflammatory effect.

Energy metabolism in major depressive disorder: Recent advances from omics technologies and imaging

Major depressive disorder (MDD) is a serious psychiatric disorder that associated with high rate of disability and increasing suicide rate, and the pathogenesis is still unclear. Many researches showed that the energy metabolism of patients with depression is impaired, which may be the direction of depression treatment. In this review, we focus on the "omics" technologies such as genomics, proteomics, transcriptomics and metabolomics, as well as imaging, and the progress on energy metabolism of MDD. These findings indicate that abnormal energy metabolism is one of the important mechanisms for the occurrence and development of depression. Although the research on various mechanisms of depression is still ongoing, the rapid development of new technologies and the joint use of various technologies will help to clarify the pathogenesis of depression and explore efficient diagnosis and treatment methods.

Hippocampal proteomic analysis reveals activation of necroptosis and ferroptosis in a mouse model of chronic unpredictable mild stress-induced depression

Neuronal loss has been identified in depression, but its mechanisms are not fully understood. Proteomic analyses provide a novel insight to explore the potential mechanisms of such pathological alterations. In this study, mice were treated with chronic unpredictable mild stress (CUMS) for 2 months to establish depression models. The hippocampus was analyzed for proteomic patterns by mass spectrometry followed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Behavioral tests showed that mice receiving CUMS showed depression-like symptoms such as anhedonia in the sucrose preference test (SPT) and behavioral despair in the forced swimming test (FST). CUMS induced anxiety-like behaviors in the open field test (OFT), but did not impair spatial learning and memory ability in the Morris water maze (MWM) test. Out of 4046 quantified proteins, 47 differentially expressed proteins were obtained between the CUMS and control groups. These proteins were functionally enriched in a series of biological processes. Among the notably enriched pathways, necroptosis and ferroptosis were significantly activated. Western blot and biochemical assay analyses identified changes in receptor-interacting protein kinase 3 (RIP3), phosphorylated mixed lineage kinase domain-like protein (p-MLKL), ferritin light chain 1 (Ftl1) and lipid peroxidation that were related to necroptosis and ferroptosis. Further, we found reduced levels of alpha-crystallin B (Cryab) and brain-derived neurotrophic factor (BDNF), which were also associated with neuronal survival. Our study highlighted that necroptosis and ferroptosis were involved in depression and partially account for neuronal loss, thereby providing potentially novel targets for the treatment of depression.

Intranasal administration of white tea alleviates the olfactory function deficit induced by chronic unpredictable mild stress

CONTEXT

White tea [Camellia sinensis (L) O.Ktze. (Theaceae)] is popular in Asia, but its benefits on olfactory injury are unknown.

OBJECTIVE

The present study explores the effects of white tea on the olfactory injury caused by chronic unpredictable mild stress (CUMS).

MATERIALS AND METHODS

C57BL/6J mice (WT) were exposed to CUMS. CUMS mice (CU) were intranasally treated with white tea extract [low tea (LT), 20 mg/kg; high tea (HT), 40 mg/kg] and fluoxetine (CF, 20 mg/kg) for 7 days. Several behavioural tests were conducted to assess depression and olfactory function. The transmission electron microscope (TEM) and semi-quantitative reverse transcription PCR were performed separately to observe the changes of related structures and genes transcription level.

RESULTS

The depressive behaviours of the LT and HT mice were reversed. The latency time of the buried food pellet test decreased from 280 s (CU) to 130 s (HT), while the olfactory sensitivity and olfactory avoidance test showed that the olfactory behaviours disorder of LT and HT mice were alleviated. The white tea increased the A_490 nm values of the cortisol treated cells from 0.15 to 1.4. Reduced mitochondrial and synaptic damage in the olfactory bulb (OB), enhanced expression of the brain-derived neurotrophic factor (BDNF) and olfactory marker protein (OMP) were observed in the LT and HT mice.

CONCLUSIONS AND DISCUSSION

White tea has the potential in curing the olfactory deficiency related to chronic stress. It lays the foundation for the development of new and reliable drug to improve olfactory.

The olfactory deficits of depressed patients are restored after remission with venlafaxine treatment

BACKGROUND

It is unclear whether olfactory deficits improve after remission in depressed patients. Therefore, we aimed to assess in drug-free patients the olfactory performance of patients with major depressive episodes (MDE) and its change after antidepressant treatment.

METHODS

In the DEP-ARREST-CLIN study, 69 drug-free patients with a current MDE in the context of major depressive disorder (MDD) were assessed for their olfactory performances and depression severity, before and after 1 (M1) and 3 (M3) months of venlafaxine antidepressant treatment. They were compared to 32 age- and sex-matched healthy controls (HCs). Olfaction was assessed with a psychophysical test, the Sniffin' Sticks test (Threshold: T score; Discrimination: D score; Identification: I score; total score: T + D + I = TDI score) and Pleasantness (pleasantness score: p score; neutral score: N score; unpleasantness score: U score).

RESULTS

As compared to HCs, depressed patients had lower TDI olfactory scores [mean (s.d.) 30.0(4.5) v. 33.3(4.2), p < 0.001], T scores [5.6(2.6) v. 7.4(2.6), p < 0.01], p scores [7.5(3.0) v. 9.8(2.8), p < 0.001)] and higher N scores [3.5(2.6) v. 2.1(1.8), p < 0.01]. T, p and N scores at baseline were independent from depression and anhedonia severity. After venlafaxine treatment, significant increases of T scores [M1: 7.0(2.6) and M3: 6.8(3.1), p < 0.01] and p scores [M1: 8.1(3.0) and M3: 8.4(3.3), p < 0.05] were evidenced, in remitters only (T: p < 0.01; P: p < 0.01). Olfaction improvement was mediated by depression improvement.

CONCLUSIONS

The olfactory signature of MDE is restored after venlafaxine treatment. This olfaction improvement is mediated by depression improvement.

Metabolomic abnormalities of purine and lipids implicated olfactory bulb dysfunction of CUMS depressive rats

Major depressive disorder (MDD) is a serious mood disorder and leads to a high suicide rate as well as financial burden. The volume and function (the sensitivity and neurogenesis) of the olfactory bulb (OB) were reported to be altered among the MDD patients and rodent models of depression. In addition, the olfactory epithelium was newly reported to decrease its volume and function under chronic unpredictable mild stress (CUMS) treatment. However, the underlying molecular mechanism still remains unclear. Herein, we conducted the non-targeted metabolomics method based on gas chromatography-mass spectrometry (GC-MS) coupled with multivariate statistical analysis to characterize the differential metabolites in OB of CUMS rats. Our results showed that 19 metabolites were categorized into two perturbed pathways: purine metabolism and lipid metabolism, which were regarded as the vital pathways concerned with dysfunction of OB. These findings indicated that the turbulence of metabolic pathways may be partly responsible for the dysfunction of OB in MDD.

Ocimum basilicum (Basil) Modulates Apoptosis and Neurogenesis in Olfactory Pulp of Mice Exposed to Chronic Unpredictable Mild Stress

BACKGROUND

Ocimum basilicum (O. basilicum) was described to have antidepressant and anxiolytic activities. Although the relationship between the main olfactory bulb (MOB) and depression was recently reported, the chronic stress-induced dysfunction of the MOB is not clearly described.

OBJECTIVES

This study aimed to assess the efficacy of inhalation of O. basilicum essential oils in improving chronic unpredictable mild stress (CUMS)-induced changes in MOB of mice and understand the mechanism underlying such effect.

MATERIALS AND METHODS

Adult male mice (n=40) were assigned into four groups included the control, CUMS-exposed, CUMS + fluoxetine (FLU), CUMS + O. basilicum. Behavioral changes, serum corticosterone level, and gene expression of GFAP, Ki 67, and caspase-3 were assessed using real-time PCR (RT-PCR). Histopathological and immunochemical examination of the MOB was performed.

RESULTS

FLU and O. basilicum significantly down-regulated (p = 0.002, p<0.001) caspase-3 gene expression indicating reduced apoptosis and up-regulated (p = 0.002, p < 0.001) Ki67 gene expression indicating enhanced neurogenesis in MOB, respectively. FLU and O. basilicum-treated mice markedly improved MOB mitral cell layer distortion and shrinkage induced by CUMS.

CONCLUSION

O. basilicum relieved both biochemically and histopathological chronic stress-induced changes in the main olfactory bulb possibly through up-regulation of gene expression of GFAP and Ki67 and down-regulation of caspase-3 in the MOB.

Commensal Microbiota Regulation of Metabolic Networks During Olfactory Dysfunction in Mice

INTRODUCTION

Recently, an increasing number of studies have focused on commensal microbiota. These microorganisms have been suggested to impact human health and disease. However, only a small amount of data exists to support the assessment of the influences that commensal microbiota exert on olfactory function.

METHODS

We used a buried food pellet test (BFPT) to investigate and compare olfactory functions in adult, male, germ-free (GF) and specific-pathogen-free (SPF) mice, then examined and compared the metabolomic profiles for olfactory bulbs (OBs) isolated from GF and SPF mice to uncover the mechanisms associated with olfactory dysfunction.

RESULTS

We found that the absence of commensal microbiota was able to influence olfactory function and the metabolic signatures of OBs, with 38 metabolites presenting significant differences between the two groups. These metabolites were primarily associated with disturbances in glycolysis, the tricarboxylic acid (TCA) cycle, amino acid metabolism, and purine catabolism. Finally, the commensal microbiota regulation of metabolic networks during olfactory dysfunction was identified, based on an integrated analysis of metabolite, protein, and mRNA levels.

CONCLUSION

This study demonstrated that the absence of commensal microbiota may impair olfactory function and disrupt metabolic networks. These findings provide a new entry-point for understanding olfactory-associated disorders and their potential underlying mechanisms.

Cang-ai volatile oil improves depressive-like behaviors and regulates DA and 5-HT metabolism in the brains of CUMS-induced rats

ETHNOPHARMACOLOGICAL RELEVANCE

Cang-ai volatile oil (CAVO) is a traditional Chinese medicine (TCM) inhalational preparation for the treatment of some depressive and emotive disorders.

AIM OF THE STUDY

This research aimed to evaluate the efficiency and possible mechanism of intranasal CAVO administration on depression in chronic unpredictable mild stress (CUMS)-induced rats compared to lavender volatile oil (LVO) treatment after CUMS exposure and bilateral olfactory bulb impairment (OBI) in rats.

MATERIALS AND METHODS

Forty depressive-like model rats induced by CUMS were evaluated by the forced swim test (FST), open field test (OFT), and sucrose preference test (SPT). The model rats were divided into five groups: CUMS (n = 8), CAVOh + CUMS (n = 8), CAVOl + CUMS (n = 8), LVO + CUMS (n = 8), and OBI + CAVO + CUMS (n = 8). The CUMS-induced rats were treated for a period of 4 weeks. The other healthy rats were regarded as the control (CTR, n = 8) subjects. The levels of serotonin (5-HT) and dopamine (DA) and their respective metabolites homovanillic acid (HVA) and 5-hydroxyindol acetic acid (5-HIAA) were measured in brain tissue homogenates of CUMS-induced rats using enzyme-linked immunosorbent assay (ELISA).

RESULTS

CAVO ameliorated depressive-like behaviors (p < 0.05). The levels of DA in the CUMS group were lower than those in the CTR and CAVOh groups (**p < 0.01 and *p < 0.05). The levels of HVA were lower in the CUMS group than in the CTR, LVO, OBI + CAVOh and CAVOh groups (**p < 0.01 and *p < 0.05) and lower in the OBI + CAVOh group than in the CAVOh group (**p < 0.01). The levels of 5-HT in the CUMS group were lower than those in the CTR and CAVOh groups (**p < 0.01). The levels of 5-HIAA were lower in the CUMS and OBI + CAVOh groups than in the CTR, LVO and CAVOh groups (**p < 0.01).

CONCLUSIONS

CAVO can improve depressive-like behaviors concomitant with the regulation of DA and 5-HT metabolism in the brains of CUMS-induced rats.

Comparative Analysis of Erythrocyte Proteomes of Water Buffalo, Dairy Cattle, and Beef Cattle by Shotgun LC-MS/MS

A number of studies have demonstrated that Babesia orientalis (B. orientalis) can only infect water buffalo (Bubalus bubalis) and not dairy cattle (Bos taurus) or beef cattle (Bos taurus), even though all three belong to the tribe Bovini and have close evolutionary relationships. In addition, Babesia species are intracellular protozoans that obligately parasitize in erythrocytes. This may indicate that the infection specificity is due to differences in erythrocyte proteins. Totals of 491, 1,143, and 1,145 proteins were identified from water buffalo, beef cattle, and dairy cattle, respectively, by searching the Uniprot and NCBI databases. The number of proteins identified for water buffalo was far lower than for beef cattle and dairy cattle, particularly in the range from 15 to 25 kDa. Remarkably, 290 identified proteins were unique to water buffalo, of which putative gamma-globin and putative epsilon-globin had a significant possibility of being relevant to the survival of B. orientalis only in water buffalo. A total of 2,222 proteins were annotated in terms of molecular function, biological process, and cellular component according to GO annotation. The number of proteins of water buffalo in oxygen binding was far higher than for beef cattle and dairy cattle. This is the first time that the protein profiles of water buffalo, beef cattle, and dairy cattle have been comparatively analyzed. The uniquely expressed proteins in water buffalo obtained in this study may provide new insights into the mechanism of B. orientalis infection exclusivity in water buffalo and may be a benefit for the development of strategies against B. orientalis.

Chronic mild stress leads to aberrant glucose energy metabolism in depressed Macaca fascicularis models

BACKGROUND

Major depressive disorder (MDD) is a pathophysiologically uncharacterized mental illness with complex etiology and clinical manifestations. Rodent depression-like models have been widely used to mimic the morbid state of depression. However, research on emotional disorders can also benefit from the use of models in non-human primates, which share a wide range of genetic and social similarities with humans.

METHODS

To investigate the pathophysiological mechanisms of depression, we established two models, naturally occurring depression cynomolgus (NOD) and social plus visual isolation-induced depression cynomolgus (SVC), imitating chronic mild or acute intense stress, respectively. We used i-TRAQ (isobaric tags for relative and absolute quantitation)-based quantitative proteomics and shotgun proteomics to identify differentially expressed proteins in cerebrospinal fluid (CSF) of the two monkey models and human MDD patients. We also used DAVID and ingenuity pathway analysis (IPA) for further bioinformatic investigation.

RESULTS

In behavioral tests, NOD monkeys achieved higher scores in depression-like and anxiety-like behavioral measures, and spent more time on ingesting, thermoregulatory, and locomotive actions than SVC monkeys. A total of 902 proteins were identified by i-TRAQ, and 40 differentially expressed proteins were identified in each of the NOD-CON1 and SVC-CON2 groups. Application of DAVID revealed dysregulation of energy metabolism in the NOD group, whereas lipid metabolism and inflammatory response pathways were significantly altered in the SVC group. Use of IPA and Cytoscape showed that the oxygen species metabolic process glycolysis I/gluconeogenesis I, accompanied by downregulation of tubulin beta 3 class III (TUBB3), RAC-alpha serine/threonine-protein kinase (AKT1), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), was the most significantly affected pathway in the NOD group. Furthermore, 152 differentially expressed proteins in human MDD patients also revealed disruption of glucose energy metabolism. Significantly aberrant energy metabolism in various brain regions and the plasma and liver of chronic unpredictable mild stress rodent samples were also observed in a previous study.

CONCLUSIONS

Our results reveal for the first time the overall CSF protein profiles of two cynomolgus monkey models of depression. We propose that chronic mild stress may affect the disruption of glucose energy metabolism in NOD cynomolgus monkeys and rodents. These findings promote our understanding of the pathophysiology of MDD and may help to identify novel therapeutic targets.

Comparison of Therapeutic Effects of TREK1 Blockers and Fluoxetine on Chronic Unpredicted Mild Stress Sensitive Rats

The animal model for depressive behavior due to chronic unpredicted mild stress (CUMS) is commonly used to evaluate antidepressant treatments. The CUMS model has faced some criticism because of the heterogeneity of behavioral effects. Spadin and SID1900 are TREK1 blockers with a quick antidepressant effect. However, to date, their effectiveness and the long-term therapeutic mechanisms are not known. We hypothesize that early intervention with TREK1 blockers can fully reverse depressive-like behaviors, that the chronic administration of TREK1 blockers has a more pronounced effect than the SSRI fluoxetine, and that its long-term therapeutic effects may be mediated by improvement of impaired neurogenesis. Furthermore, we optimized the use of the CUMS model for increased homogeneity by screening the rats after the CUMS induction procedure. Depressive-like behavior was assessed by a forced swimming test, sucrose preference, and open field tests. To evaluate neurogenesis, cell proliferation and newly generated cell apoptosis were measured in the hippocampal dentate gyrus. Of 32 rats that underwent the CUMS procedure, 26 rats that exhibited depressive-like behaviors were grouped as CUMS sensitive rats (CUMSS), while six that did not were grouped as CUMS resistant ones (CUMSR). The CUMSR rats exhibited minor neurogenesis impairments, while the CUMSS rats had a more pronounced effect. Treatment with TREK1 blockers could reverse depressive-like behaviors at least 1 week earlier than that of fluoxetine. Chronic administration of both the TREK1 blockers and fluoxetine could restore neurogenesis impairments. This study underlines the importance of model validation by determination of CUMS sensitivity. The TREK1 blockers were found to have an effect that was more rapid and more pronounced than that of fluoxetine. Therapeutic benefits after chronic administration were associated with a restoration of impaired neurogenesis.

Activation of ERK/CREB/BDNF pathway involved in abnormal behavior of neonatally Borna virus-infected rats

BACKGROUND

Neuropsychiatric disorders are devastating illnesses worldwide; however, the potential involvement of viruses in the pathophysiological mechanisms of psychiatric diseases have not been clearly elucidated. Borna disease virus (BDV) is a neurotropic, noncytopathic RNA virus.

MATERIALS AND METHODS

In this study, we infected neonatal rats intracranially with BDV Hu-H1 and Strain V within 24 hours of birth. Psychological phenotypes were assessed using sucrose preference test, open field test, elevated plus maze test, and forced swim test. The protein expression of ERK/CREB/BDNF pathway was assessed by Western blotting of in vitro and in vivo samples.

RESULTS

Hu-H1-infected rats showed anxiety-like behavior 8 weeks postinfection while Strain V-infected rats demonstrated a certain abnormal behavior. Phosphorylated ERK1/2 was significantly upregulated in the hippocampi of Strain V- and Hu-H1-infected rats compared with control rats, indicating that Raf/MEK/ERK signaling was activated.

CONCLUSION

The data suggested that infection of neonatal rats with BDV Hu-H1 and Strain V caused behavioral abnormalities that shared common molecular pathways, providing preliminary evidences to investigate the underlying mechanisms of psychiatric disorders caused by BDV.

Quantitative proteomic study of the plasma reveals acute phase response and LXR/RXR and FXR/RXR activation in the chronic unpredictable mild stress mouse model of depression

Major depressive disorder is a severe neuropsychiatric disease that negatively impacts the quality of life of a large portion of the population. However, the molecular mechanisms underlying depression are still unclear. The pathogenesis of depression involves several brain regions. However, most previous studies have focused only on one specific brain region. Plasma and brain tissues exchange numerous components through the blood-brain barrier. Therefore, in the present study, plasma samples from control (CON) mice and mice subjected to chronic unpredictable mild stress (CUMS) were used to investigate the molecular pathogenesis of depression, and the association between the peripheral circulation and the central nervous system. A total of 47 significant differentially expressed proteins were identified between the CUMS and CON group by an isobaric tag for relative and absolute quantitation (iTRAQ) coupled with tandem mass spectrometry approach. These 47 differentially expressed proteins were analyzed with ingenuity pathway analysis (IPA) software. This revealed that the acute phase response, LXR/RXR and FXR/RXR activation, the complement system and the intrinsic prothrombin activation pathway were significantly changed. Four of the significant differentially expressed proteins (lipopolysaccharide binding protein, fibrinogen β chain, α-1 antitrypsin, and complement factor H) were validated by western blotting. the present findings provide a novel insight into the molecular pathogenesis of depression.