Dynamic regulation of phosphorylation of NMDA receptor GluN2B subunit tyrosine residues mediates ketamine rapid antidepressant effects.

The rapid antidepressant effects of ketamine depend on the N-methyl-D-aspartate (NMDA) receptor containing 2B subunit (NR2B), whose function is influenced by its phosphorylated regulation and distribution within and outside synapses. It remains unclear if ketamine's rapid onset of antidepressant effects relies on the dynamic phosphorylated regulation of NR2B within and outside synapses. Here, we show that ketamine rapidlyalleviated depression-like behaviors and normalized abnormal expression of pTyr1472NR2B and striatal-enriched protein tyrosine phosphatase (STEP) 61 within and outside synapses in the medial prefrontal cortex (mPFC) induced by chronic unpredictable stress (CUS) and conditional knockdown of STEP 61, a key phosphatase of NR2B, within 1 hour after administration Together, our results delineate the rapid initiation of ketamine's antidepressant effects results from the restoration of NR2B phosphorylation homeostasis within and outside synapses. The dynamic regulation of phosphorylation of NR2B provides a new perspective for developing new antidepressant strategies.

Gut microbiota modulates the inflammatory response and cognitive impairment induced by sleep deprivation.

Sleep deprivation (SD) is increasingly common in modern society, which can lead to the dysregulation of inflammatory responses and cognitive impairment, but the mechanisms remain unclear. Emerging evidence suggests that gut microbiota plays a critical role in the pathogenesis and development of inflammatory and psychiatric diseases, possibly via gut microbiota-brain interactions and neuroinflammation. The present study investigated the impact of SD on gut microbiota composition and explored whether alterations of the gut microbiota play a causal role in chronic inflammatory states and cognitive impairment that are induced by SD. We found that SD-induced gut dysbiosis, inflammatory responses, and cognitive impairment in humans. Moreover, the absence of the gut microbiota suppressed inflammatory response and cognitive impairment induced by SD in germ-free (GF) mice. Transplantation of the "SD microbiota" into GF mice activated the Toll-like receptor 4/nuclear factor-κB signaling pathway and impaired cognitive function in the recipient mice. Mice that harbored "SD microbiota" also exhibited increases in neuroinflammation and microglial activity in the hippocampus and medial prefrontal cortex. These findings indicate that gut dysbiosis contributes to both peripheral and central inflammatory processes and cognitive deficits that are induced by SD, which may open avenues for potential interventions that can relieve the detrimental consequences of sleep loss.

Spatio-temporal dynamics of EEG features during sleep in major depressive disorder after treatment with escitalopram: a pilot study.

BACKGROUND: Previous studies have shown escitalopram is related to sleep quality. However, effects of escitalopram on dynamics of electroencephalogram (EEG) features especially during different sleep stages have not been reported. This study may help to reveal pharmacological mechanism underlying escitalopram treatment. METHODS: The spatial and temporal responses of patients with major depressive disorder (MDD) to escitalopram treatment were analyzed in this study. Eleven MDD patients and eleven healthy control subjects who completed eight weeks' treatment of escitalopram were included in the final statistics. Six-channel sleep EEG signals were acquired during sleep. Power spectrum and nonlinear dynamics were used to analyze the spatio-temporal dynamics features of the sleep EEG after escitalopram treatment. RESULTS: For temporal dynamics: after treatment, there was a significant increase in the relative energy (RE) of Î´1 band (0.5 - 2 Hz), accompanied by a significant decrease in the RE of ß2 band (20 - 30 Hz). Lempel-Ziv complexity and Co - complexity values were significantly lower. EEG changes at different sleep stages also showed the same regulation as throughout the night sleep. For spatio dynamics: after treatment, the EEG response of the left and right hemisphere showed asymmetry. Regarding band-specific EEG complexity estimations, δ1 and ß2 in stage-1 and δ1 in stage-2 sleep stage in frontal cortex is found to be much more sensitive to escitalopram treatment in comparison to central and occipital cortices. CONCLUSIONS: The sleep quality of MDD patients improved, EEG response occurred asymmetry in left and right hemispheres due to escitalopram treatment, and frontal cortex is found to be much more sensitive to escitalopram treatment. These findings may contribute to a comprehensive understanding of the pharmacological mechanism of escitalopram in the treatment of depression.

BDNF-GSK-3ß-ß-Catenin Pathway in the mPFC Is Involved in Antidepressant-Like Effects of Morinda officinalis Oligosaccharides in Rats.

Background: Morinda officinalis oligosaccharides have been reported to exert neuroprotective and antidepressant-like effects in the forced swim test in mice. However, the mechanisms that underlie the antidepressant-like effects of Morinda officinalis oligosaccharides are unclear. Methods: Chronic unpredictable stress and forced swim test were used to explore the antidepressant-like effects of Morinda officinalis oligosaccharides and resilience to stress in rats. The phosphoinositide-3 kinase inhibitor LY294002 was microinjected in the medial prefrontal cortex to explore the role of glycogen synthase kinase-3ß in the antidepressant-like effects of Morinda officinalis oligosaccharides. The expression of brain-derived neurotrophic factor, phosphorylated-Ser9-glycogen synthase kinase 3ß, ß-catenin, and synaptic proteins was determined in the medial prefrontal cortex and the orbitofrontal cortex by western blot. Results: We found that Morinda officinalis oligosaccharides effectively ameliorated chronic unpredictable stress-induced depression-like behaviors in the sucrose preference test and forced swim test. The Morinda officinalis oligosaccharides also significantly rescued chronic unpredictable stress-induced abnormalities in the brain-derived neurotrophic factor-glycogen synthase kinase-3ß-ß-catenin pathway and synaptic protein deficits in the medial prefrontal cortex but not orbitofrontal cortex. The activation of glycogen synthase kinase-3ß by the phosphoinositide-3 kinase inhibitor LY294002 abolished the antidepressant-like effects of Morinda officinalis oligosaccharides in the forced swim test. Naïve rats that were treated with Morinda officinalis oligosaccharides exhibited resilience to chronic unpredictable stress, accompanied by increases in the expression of brain-derived neurotrophic factor, phosphorylated-Ser9-glycogen synthase kinase-3ß, and ß-catenin in the medial prefrontal cortex. Conclusion: Our findings indicate that the brain-derived neurotrophic factor-glycogen synthase kinase-3ß-ß-catenin pathway in the medial prefrontal cortex may underlie the antidepressant-like effect of Morinda officinalis oligosaccharides and resilience to stress.

Effects of environmental stress on the depression-like behaviors and the diurnal rhythm of corticosterone and melatonin in male rats.

Environmental stress (ES) is commonly used in producing chronic unpredictable mild stress to study pathogenesis of depression, including the regulatory role of circadian system on depression. However, the direct effect of ES on the circadian system has been rarely explored. The present study was aimed to investigate the effect of ES on depression-like behaviors and diurnal rhythm of plasma hormone/peptide levels in male rats. Rats were allocated into control group (CON group), low frequency ES group (LF group) and high frequency ES group (HF group). Sucrose preference test (SPT), open field test (OFT), weight gain, food and water intake were conducted to assess depression- and anxiety-like behaviors. A total of 7 times of the tail venous blood was collected with an interval of 4 h during 24 h from other rats who subjected to the same procedures of ES but not the behavioral tests. The alterations of diurnal rhythm of peripheral plasma corticosterone (CORT) and melatonin, and changes of the cholecystokinin (CCK), neuropeptide Y and leptin levels at zeitgeber time (ZT) 0 were detected by using enzyme-linked immunosorbent assay (ELISA). We found that ES led to a disturbance of diurnal rhythm of CORT and melatonin in the plasma. Besides, it also increased plasma leptin level and decreased body weight gain, but it did not produce depression- and anxiety-like behaviors compared with those rats in the control group. In short, our findings indicated that the ES could induce a disturbance of diurnal rhythm of plasma CORT and melatonin in male rats.

Mitochondrial DNA copy number, but not haplogroup is associated with keratoconus in Han Chinese population.

Oxidative stress may play a role in the pathogenesis of keratoconus (KC). Mitochondrial DNA (mtDNA) is closely related to mitochondrion function, and variations may affect the generation of reactive oxygen species (ROS) and be involved in the pathogenesis of KC. To test whether mtDNA background and copy number confer genetic susceptibility to KC in the Han Chinese population, we performed this association study. We analyzed mtDNA sequence variations in 210 KC patients and 309 matched individuals from China, and classified each subject by haplogroup. Mitochondrial DNA copy number was measured in a subset of these subjects (193 patients and 103 controls). Comparison of matrilineal components of the cases and control populations revealed no significant difference. However, measurement of mtDNA copy number showed that KC patients had significantly lower mtDNA copy numbers than controls (P = 0.0002), even when age, gender, and mtDNA background were considered. Our results suggest that mtDNA copy number, but not haplogroup, is associated with keratoconus, and may contribute to its pathogenesis.

Role of the NMDA receptor in cognitive deficits, anxiety and depressive-like behavior in juvenile and adult mice after neonatal dexamethasone exposure.

Postnatal dexamethasone (DEX) therapy has been used to treat or prevent chronic lung disease after premature births. However, there are many reports of long-term negative neurodevelopmental sequelae following this treatment. In contrast, hydrocortisone (HYD), which has fewer neurodevelopment adverse effects, is used as an alternative for DEX. In this study, we report that neonatal DEX exposure (days 1-3) caused alterations of amino acids affecting N-methyl-d-aspartate (NMDA) receptor neurotransmission in mouse brains. Neonatal DEX, but not HYD, exposure (days 1-3) significantly decreased the GluN2B subunit of NMDA receptor in the hippocampus at juvenile and adult stages. Mice treated with DEX showed cognitive deficits, as well as anxiety and depressive-like behavior at juvenile and adult stages. In contrast, mice treated with HYD (days 1-3) showed no behavioral abnormalities at these stages. In the DEX suppression test, plasma levels of corticosterone in mice exposed neonatally to DEX and HYD were significantly higher at juvenile, but not adult stages. Pretreatment with Ro 63-1908, an antagonist at GluN2B subunit, 30min before each injection of DEX, prevented cognitive deficits, as well as anxiety and depressive-like behavior in juvenile and adult mice. Interestingly, subsequent repeated (days 29-33) administration of Ro 63-1908 or L701324, an antagonist of the glycine modulatory site on the NMDA receptor, significantly suppressed behavioral abnormalities in juvenile and adult mice after neonatal DEX exposure. These results indicate that neonatal DEX, but not HYD, exposure produced behavioral abnormalities in juvenile and adult mice by altering glutamatergic neurotransmission via the NMDA receptor. The NMDA receptor antagonists may prevent or treat these DEX-induced neonatal behavioral abnormalities in later life.

Xeroderma pigmentosum complementation group D (XPD) gene polymorphisms contribute to bladder cancer risk: a meta-analysis.

Numerous epidemiological studies have been conducted to investigate the association between Xeroderma pigmentosum complementation group D (XPD) Asp312Asn (rs1799793 G > A) and Lys751Gln (rs13181 A > C) polymorphisms and bladder cancer risk; however, the conclusions remain controversial. With this in mind, we performed this meta-analysis with 11 studies including 3,797 cases and 5,094 controls for Asp312Asn and 21 studies including 6,360 cases and 7,894 controls for Lys751Gln polymorphism. We searched available literatures from PubMed, Embase, and CBM databases. Crude odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the strength of the associations. Moreover, to validate biological plausibility of our findings, the effects of these two polymorphisms on XPD gene expression within three ethnicities was determine by gene expression analysis based on imputed genotypes from HapMap. Overall, the variant allele of Asp312Asn polymorphism was associated with an increased risk of bladder cancer (Asn/Asn vs. Asp/Asp: OR = 1.51, 95% CI = 1.19-1.91; Asp/Asn vs. Asp/Asp: OR = 1.23, 95% CI = 1.12-1.35; recessive model: OR = 1.33, 95% CI = 1.10-1.61; dominant model: OR = 1.32, 95% CI = 1.14-1.52; and allele comparing: OR = 1.26, 95% CI = 1.11-1.42). We found the Lys751Gln was associated with increased bladder cancer risk only under the recessive model (OR = 1.14, 95% CI = 1.01-1.29). Stratification analyses demonstrated an increased risk for Asians and hospital-based studies under all genetic models while only under the dominant model for Caucasians as to the Asp312Asn polymorphism and for Caucasians under the recessive model as to the Lys751Gln polymorphism. We also found the Asp312Asn polymorphism can significantly influence mRNA expression levels among Asians and Caucasians, and the Lys751Gln polymorphism has a similar effect for Caucasians. Despite some limitations, this meta-analysis suggests that polymorphisms in XPD gene may contribute to bladder cancer susceptibility. These findings need further validation by large well-designed prospective studies.

Antidepressant effects of TrkB ligands on depression-like behavior and dendritic changes in mice after inflammation.

BACKGROUND: Brain-derived neurotrophic factor (BDNF) and its receptor, tropomyosin-related kinase B (TrkB), signaling represent potential therapeutic targets for major depressive disorder. The purpose of this study is to examine whether TrkB ligands show antidepressant effects in an inflammation-induced model of depression. METHODS: In this study, we examined the effects of TrkB agonist 7,8-dihydroxyflavone (7,8-DHF) and TrkB antagonist ANA-12 on depression-like behavior and morphological changes in mice previously exposed to lipopolysaccharide (LPS). Protein levels of BDNF, phospho-TrkB (p-TrkB), and TrkB in the brain regions were also examined. RESULTS: LPS caused a reduction of BDNF in the CA3 and dentate gyrus (DG) of the hippocampus and prefrontal cortex (PFC), whereas LPS increased BDNF in the nucleus accumbens (NAc). Dexamethason suppression tests showed hyperactivity of the hypothalamic-pituitary-adrenal axis in LPS-treated mice. Intraperitoneal (i.p.) administration of 7,8-DHF showed antidepressant effects on LPS-induced depression-like behavior, and i.p. pretreatment with ANA-12 blocked its antidepressant effects. Surprisingly, ANA-12 alone showed antidepressant-like effects on LPS-induced depression-like behavior. Furthermore, bilateral infusion of ANA-12 into the NAc showed antidepressant effects. Moreover, LPS caused a reduction of spine density in the CA3, DG, and PFC, whereas LPS increased spine density in the NAc. Interestingly, 7,8-DHF significantly attenuated LPS-induced reduction of p-TrkB and spine densities in the CA3, DG, and PFC, whereas ANA-12 significantly attenuated LPS-induced increases of p-TrkB and spine density in the NAc. CONCLUSIONS: The results suggest that LPS-induced inflammation may cause depression-like behavior by altering BDNF and spine density in the CA3, DG, PFC, and NAc, which may be involved in the antidepressant effects of 7,8-DHF and ANA-12, respectively.

Heterologous overexpression of Vigna radiata epoxide hydrolase in Escherichia coli and its catalytic performance in enantioconvergent hydrolysis of p-nitrostyrene oxide into (R)-p-nitrophenyl glycol.

Two native epoxide hydrolases (EHs) were previously discovered from mung bean powder (Vigna radiata), both of which can catalyze the enantioconvergent hydrolysis of p-nitrostyrene oxide (pNSO). In this study, the encoding gene of VrEH1 was successfully cloned from the cDNA of V. radiata by RT-PCR and rapid amplification of cDNA ends (RACE) technologies. High homologies were found to two putative EHs originated from Glycine max (80%) and Medicago truncatula (79%). The vreh1 gene constructed in pET28a(+) vector was then heterologously overexpressed in Escherichia coli BL21(DE3), and the encoded protein was purified to homogeneity by nickel affinity chromatography. It was shown that VrEH1 has an optimum activity at 45 °C and is very thermostable with an inactivation energy of 468 kJ mol(-1). The enzyme has no apparent requirement of metal ions for activity, and its activity was strongly inhibited by 1 mM of Ni(2+), Cu(2+), Fe(2+), or Co(2+). By adding 0.1% Triton X-100, the enzyme activity could be significantly increased up to 340%. VrEH1 shows an unusual ability of enantioconvergent catalysis for the hydrolysis of racemic pNSO, affording (R)-p-nitrophenyl glycol (pNPG). It displays opposite regioselectivity toward (S)-pNSO (83% to Cα) in contrast to (R)-pNSO (87% to Cß). The K M and k cat of VrEH1 were determined to be 1.4 mM and 0.42 s(-1) for (R)-pNSO and 5.5 mM and 6.2 s(-1) for (S)-pNSO. This thermostable recombinant VrEH1 with enantioconvergency is considered to be a promising biocatalyst for the highly productive preparation of enantiopure vicinal diols and also a good model for understanding the mechanism of EH stereoselectivity.