Reduced nucleus accumbens functional connectivity in reward network and default mode network in patients with recurrent major depressive disorder.

The nucleus accumbens (NAc) is considered a hub of reward processing and a growing body of evidence has suggested its crucial role in the pathophysiology of major depressive disorder (MDD). However, inconsistent results have been reported by studies on reward network-focused resting-state functional MRI (rs-fMRI). In this study, we examined functional alterations of the NAc-based reward circuits in patients with MDD via meta- and mega-analysis. First, we performed a coordinated-based meta-analysis with a new SDM-PSI method for all up-to-date rs-fMRI studies that focused on the reward circuits of patients with MDD. Then, we tested the meta-analysis results in the REST-meta-MDD database which provided anonymous rs-fMRI data from 186 recurrent MDDs and 465 healthy controls. Decreased functional connectivity (FC) within the reward system in patients with recurrent MDD was the most robust finding in this study. We also found disrupted NAc FCs in the DMN in patients with recurrent MDD compared with healthy controls. Specifically, the combination of disrupted NAc FCs within the reward network could discriminate patients with recurrent MDD from healthy controls with an optimal accuracy of 74.7%. This study confirmed the critical role of decreased FC in the reward network in the neuropathology of MDD. Disrupted inter-network connectivity between the reward network and DMN may also have contributed to the neural mechanisms of MDD. These abnormalities have potential to serve as brain-based biomarkers for individual diagnosis to differentiate patients with recurrent MDD from healthy controls.

The DIRECT consortium and the REST-meta-MDD project: towards neuroimaging biomarkers of major depressive disorder.

Despite a growing neuroimaging literature on the pathophysiology of major depressive disorder (MDD), reproducible findings are lacking, probably reflecting mostly small sample sizes and heterogeneity in analytic approaches. To address these issues, the Depression Imaging REsearch ConsorTium (DIRECT) was launched. The REST-meta-MDD project, pooling 2428 functional brain images processed with a standardized pipeline across all participating sites, has been the first effort from DIRECT. In this review, we present an overview of the motivations, rationale, and principal findings of the studies so far from the REST-meta-MDD project. Findings from the first round of analyses of the pooled repository have included alterations in functional connectivity within the default mode network, in whole-brain topological properties, in dynamic features, and in functional lateralization. These well-powered exploratory observations have also provided the basis for future longitudinal hypothesis-driven research. Following these fruitful explorations, DIRECT has proceeded to its second stage of data sharing that seeks to examine ethnicity in brain alterations in MDD by extending the exclusive Chinese original sample to other ethnic groups through international collaborations. A state-of-the-art, surface-based preprocessing pipeline has also been introduced to improve sensitivity. Functional images from patients with bipolar disorder and schizophrenia will be included to identify shared and unique abnormalities across diagnosis boundaries. In addition, large-scale longitudinal studies targeting brain network alterations following antidepressant treatment, aggregation of diffusion tensor images, and the development of functional magnetic resonance imaging-guided neuromodulation approaches are underway. Through these endeavours, we hope to accelerate the translation of functional neuroimaging findings to clinical use, such as evaluating longitudinal effects of antidepressant medications and developing individualized neuromodulation targets, while building an open repository for the scientific community.

Disrupted intrinsic functional brain topology in patients with major depressive disorder.

Aberrant topological organization of whole-brain networks has been inconsistently reported in studies of patients with major depressive disorder (MDD), reflecting limited sample sizes. To address this issue, we utilized a big data sample of MDD patients from the REST-meta-MDD Project, including 821 MDD patients and 765 normal controls (NCs) from 16 sites. Using the Dosenbach 160 node atlas, we examined whole-brain functional networks and extracted topological features (e.g., global and local efficiency, nodal efficiency, and degree) using graph theory-based methods. Linear mixed-effect models were used for group comparisons to control for site variability; robustness of results was confirmed (e.g., multiple topological parameters, different node definitions, and several head motion control strategies were applied). We found decreased global and local efficiency in patients with MDD compared to NCs. At the nodal level, patients with MDD were characterized by decreased nodal degrees in the somatomotor network (SMN), dorsal attention network (DAN) and visual network (VN) and decreased nodal efficiency in the default mode network (DMN), SMN, DAN, and VN. These topological differences were mostly driven by recurrent MDD patients, rather than first-episode drug naive (FEDN) patients with MDD. In this highly powered multisite study, we observed disrupted topological architecture of functional brain networks in MDD, suggesting both locally and globally decreased efficiency in brain networks.

Brain structural alterations in MDD patients with gastrointestinal symptoms: Evidence from the REST-meta-MDD project.

OBJECTIVE: While gastrointestinal (GI) symptoms are very common in patients with major depressive disorder (MDD), few studies have investigated the neural basis behind these symptoms. In this study, we sought to elucidate the neural basis of GI symptoms in MDD patients by analyzing the changes in regional gray matter volume (GMV) and gray matter density (GMD) in brain structure. METHOD: Subjects were recruited from 13 clinical centers and categorized into three groups, each of which is based on the presence or absence of GI symptoms: the GI symptoms group (MDD patients with at least one GI symptom), the non-GI symptoms group (MDD patients without any GI symptoms), and the healthy control group (HCs). Structural magnetic resonance images (MRI) were collected of 335 patients in the GI symptoms group, 149 patients in the non-GI symptoms group, and 446 patients in the healthy control group. The 17-item Hamilton Depression Rating Scale (HAMD-17) was administered to all patients. Correlation analysis and logistic regression analysis were used to determine if there was a correlation between the altered brain regions and the clinical symptoms. RESULTS: There were significantly higher HAMD-17 scores in the GI symptoms group than that of the non-GI symptoms group (P < 0.001). Both GMV and GMD were significant different among the three groups for the bilateral superior temporal gyrus, bilateral middle temporal gyrus, left lingual gyrus, bilateral caudate nucleus, right Fusiform gyrus and bilateral Thalamus (GRF correction, cluster-P < 0.01, voxel-P < 0.001). Compared to the HC group, the GI symptoms group demonstrated increased GMV and GMD in the bilateral superior temporal gyrus, and the non-GI symptoms group demonstrated an increased GMV and GMD in the right superior temporal gyrus, right fusiform gyrus and decreased GMV in the right Caudate nucleus (GRF correction, cluster-P < 0.01, voxel-P < 0.001). Compared to the non-GI symptoms group, the GI symptoms group demonstrated significantly increased GMV and GMD in the bilateral thalamus, as well as decreased GMV in the bilateral superior temporal gyrus and bilateral insula lobe (GRF correction, cluster-P < 0.01, voxel-P < 0.001). While these changed brain areas had significantly association with GI symptoms (P < 0.001), they were not correlated with depressive symptoms (P > 0.05). Risk factors for gastrointestinal symptoms in MDD patients (p < 0.05) included age, increased GMD in the right thalamus, and decreased GMV in the bilateral superior temporal gyrus and left Insula lobe. CONCLUSION: MDD patients with GI symptoms have more severe depressive symptoms. MDD patients with GI symptoms exhibited larger GMV and GMD in the bilateral thalamus, and smaller GMV in the bilateral superior temporal gyrus and bilateral insula lobe that were correlated with GI symptoms, and some of them and age may contribute to the presence of GI symptoms in MDD patients.

Common and Specific Alterations of Amygdala Subregions in Major Depressive Disorder With and Without Anxiety: A Combined Structural and Resting-State Functional MRI Study.

Anxious major depressive disorder is a common subtype of major depressive disorder; however, its unique neural mechanism is not well-understood currently. Using multimodal MRI data, this study examined common and specific alterations of amygdala subregions between patients with and without anxiety. No alterations were observed in the gray matter volume or intra-region functional integration in either patient group. Compared with the controls, both patient groups showed decreased functional connectivity between the left superficial amygdala and the left putamen, and between the right superficial amygdala and the bilateral anterior cingulate cortex and medial orbitofrontal cortex, while only patients with anxiety exhibited decreased activity in the bilateral laterobasal and superficial amygdala. Moreover, the decreased activity correlated negatively with the Hamilton depression scale scores in the patients with anxiety. These findings provided insights into the pathophysiologic processes of anxious major depressive disorder and may help to develop new and effective treatment programs.

Disrupted hemispheric connectivity specialization in patients with major depressive disorder: Evidence from the REST-meta-MDD Project.

BACKGROUND: Functional specialization is a feature of human brain for understanding the pathophysiology of major depressive disorder (MDD). The degree of human specialization refers to within and cross hemispheric interactions. However, most previous studies only focused on interhemispheric connectivity in MDD, and the results varied across studies. Hence, brain functional connectivity asymmetry in MDD should be further studied. METHODS: Resting-state fMRI data of 753 patients with MDD and 451 healthy controls were provided by REST-meta-MDD Project. Twenty-five project contributors preprocessed their data locally with the Data Processing Assistant State fMRI software and shared final indices. The parameter of asymmetry (PAS), a novel voxel-based whole-brain quantitative measure that reflects inter- and intrahemispheric asymmetry, was reported. We also examined the effects of age, sex and clinical variables (including symptom severity, illness duration and three depressive phenotypes). RESULTS: Compared with healthy controls, patients with MDD showed increased PAS scores (decreased hemispheric specialization) in most of the areas of default mode network, control network, attention network and some regions in the cerebellum and visual cortex. Demographic characteristics and clinical variables have significant effects on these abnormalities. LIMITATIONS: Although a large sample size could improve statistical power, future independent efforts are needed to confirm our results. CONCLUSIONS: Our results highlight the idea that many brain networks contribute to broad clinical pathophysiology of MDD, and indicate that a lateralized, efficient and economical brain information processing system is disrupted in MDD. These findings may help comprehensively clarify the pathophysiology of MDD in a new hemispheric specialization perspective.

Biotypes of major depressive disorder: Neuroimaging evidence from resting-state default mode network patterns.

BACKGROUND: Major depressive disorder (MDD) is heterogeneous disorder associated with aberrant functional connectivity within the default mode network (DMN). This study focused on data-driven identification and validation of potential DMN-pattern-based MDD subtypes to parse heterogeneity of the disorder. METHODS: The sample comprised 1397 participants including 690 patients with MDD and 707 healthy controls (HC) registered from multiple sites based on the REST-meta-MDD Project in China. Baseline resting-state functional magnetic resonance imaging (rs-fMRI) data was recorded for each participant. Discriminative features were selected from DMN between patients and HC. Patient subgroups were defined by K-means and principle component analysis in the multi-site datasets and validated in an independent single-site dataset. Statistical significance of resultant clustering were confirmed. Demographic and clinical variables were compared between identified patient subgroups. RESULTS: Two MDD subgroups with differing functional connectivity profiles of DMN were identified in the multi-site datasets, and relatively stable in different validation samples. The predominant dysfunctional connectivity profiles were detected among superior frontal cortex, ventral medial prefrontal cortex, posterior cingulate cortex and precuneus, whereas one subgroup exhibited increases of connectivity (hyperDMN MDD) and another subgroup showed decreases of connectivity (hypoDMN MDD). The hyperDMN subgroup in the discovery dataset had age-related severity of depressive symptoms. Patient subgroups had comparable demographic and clinical symptom variables. CONCLUSIONS: Findings suggest the existence of two neural subtypes of MDD associated with different dysfunctional DMN connectivity patterns, which may provide useful evidence for parsing heterogeneity of depression and be valuable to inform the search for personalized treatment strategies.

Reduced default mode network functional connectivity in patients with recurrent major depressive disorder.

Major depressive disorder (MDD) is common and disabling, but its neuropathophysiology remains unclear. Most studies of functional brain networks in MDD have had limited statistical power and data analysis approaches have varied widely. The REST-meta-MDD Project of resting-state fMRI (R-fMRI) addresses these issues. Twenty-five research groups in China established the REST-meta-MDD Consortium by contributing R-fMRI data from 1,300 patients with MDD and 1,128 normal controls (NCs). Data were preprocessed locally with a standardized protocol before aggregated group analyses. We focused on functional connectivity (FC) within the default mode network (DMN), frequently reported to be increased in MDD. Instead, we found decreased DMN FC when we compared 848 patients with MDD to 794 NCs from 17 sites after data exclusion. We found FC reduction only in recurrent MDD, not in first-episode drug-naïve MDD. Decreased DMN FC was associated with medication usage but not with MDD duration. DMN FC was also positively related to symptom severity but only in recurrent MDD. Exploratory analyses also revealed alterations in FC of visual, sensory-motor, and dorsal attention networks in MDD. We confirmed the key role of DMN in MDD but found reduced rather than increased FC within the DMN. Future studies should test whether decreased DMN FC mediates response to treatment. All R-fMRI indices of data contributed by the REST-meta-MDD consortium are being shared publicly via the R-fMRI Maps Project.

Caspase-8 Mediates Amyloid-ß-induced Apoptosis in Differentiated PC12 Cells.

The pathogenesis of Alzheimer's disease (AD) is very complex and there are currently no significant treatments for the disease. Caspase-8 is known to be involved in neuronal apoptosis. To explore a possible molecular mechanisms involved in AD pathology, this study investigated the effect of caspase-8 knockdown on amyloid-ß 1-40 (Aß1-40)-induced apoptosis in PC12 cells. The proliferation of PC12 cells was significantly inhibited in Aß-treated cells, and a high fraction of the cells underwent apoptosis in a dose- and time-dependent manner. Transfection of caspase-8 small interfering RNA (siRNA) resulted in reduced apoptosis following Aß1-40 treatment. The activation of caspase-3, caspase-8, and caspase-9 was stimulated by Aß1-40, an effect that was also significantly reduced by caspase-8 siRNA. Knockdown of caspase-8 increased the phosphorylation of the signaling molecules AKT and ERK1/2 relative to cells treated with Aß1-40 alone. Caspase-8 is an important effector molecule involved in apoptosis induced by Aß1-40 and is likely involved in AD pathology. This study suggests that targeted inhibition of caspase-8 may be a new therapeutic for preventing neuronal apoptosis and inhibiting the progression of AD.

Roles of the prostaglandin E2 receptors EP subtypes in Alzheimer's disease.

Neuroinflammation has always been of concern in the pathogenesis of Alzheimer's disease (AD). As a major inflammatory mediator, prostaglandin E(2) (PGE(2)) plays an important role in the inflammatory process of AD. Up to now, there is still controversy on the neuroprotective or neurotoxic role of PGE(2). However, the role of PGE(2) in neurodegeneration may be far more complex, due to the 4 EP receptor subtypes. This article aims to summarize the relationship between PGE(2) receptor EP subtypes and AD. It is believed that a better understanding of the PGE(2) receptor EP subtypes may help to clarify the relation between inflammation and AD, and to develop novel therapeutic strategies targeting specific EP receptor for AD treatment.

[Cordyceps sinensis polysaccharide enhances apoptosis of HL-60 cells induced by triptolide].

OBJECTIVE: To investigate the effects of polysaccharide fraction of Cordyceps sinensis (PSCS) on triptolide (TPL)-induced apoptosis in the HL-60 cells and the involved molecular mechanism. METHODS: The cultured leukemia HL-60 cells were divided into three groups: control group, TPL group (cells were treated with 5 ng/ml TPL only), and PSCS+TPL cells group (cells treated with 5 ng/ml TPL and 100 microg/ml or 200 microg/ml PSCS for 18 h). Cell viability was tested by MTT assay and apoptotic cells were quantitatively measured by flow cytometry with Annexin V/PI double stain.The expressions of Caspase-3, 6, 7, 9 and NF-kappa B proteins were tested by Western blot. RESULT: MTT assay showed that different concentrations of PSCS inhibited the cell viability. Flow cytometry indicated that TPL markedly increased the apoptosis rate of the HL-60 cells, and PSCS enhanced the apoptosis in a dose-dependent manner. Western blot showed that TPL did not inhibit the expression of the Caspase-3, 6, 7, 9 and NF-kappa B proteins, and when cells were treated with PSCS, the expression of proteins decreased with the PSCS concentration rising. CONCLUSION: PSCS can enhance TPL-induced apoptosis in HL-60 cells and inhibit the expression of NF-kappa B and Caspase 3,6,7,9,which might be the possible signaling pathway of inducing apoptosis.

[Study of Fufang Haishe capsule against cell apoptosis].

OBJECTIVE: To study mechanismt of Fufang Haishe capsule for dementia by observing the effect of it on PC-12 cell apoptosis, which was induced by beta-amyloid protein (Abl-42). METHOD: Nerve growth factor (NGF) was used to cultivate the PC-12 cells. Fufang Haishe capsule at different concentrations was added into the culture medium so as to identify the nontoxic concentrations with MTT. To analyze the PC-12 cell apoptosis respectively by MTT assay, Flow cytometry (FCM technique) with different concentrations of Fufang Haishe capsule (0.01, 0.1, 1, 5 mg x mL(-1)), adding Ab or not Western blot was used to detect apoptosis which was measured on the implementation of caspase-9 and caspase-3 activity. RESULT: Fufang Haishe capsule could significantly inhibit the apoptosis of PC-12 cells induced by Abeta with increased colorimetric MTT asay ( compare among the control group and concentration 0, 0.01, 0.1, 1 and 5 mg x mL(-1) group, which is the same below: 1.75 +/- 0.12, 0.73 +/- 0.35, 0.79 +/- 0.11, 0.83 +/- 0.07, 1.31 +/- 0.07, 1.80 +/- 0.38, P < 0.01) and the decreased apoptosis rate of the cells which was analysed by flow cytometry (1.93 +/- 0.41)%, (46.17 +/- 4.08)%, (35.35 +/- 4.63)%, (28.62 +/- 3.81)%, (15.13 +/- 3.15)%, (7.84 +/- 1.76)%, P < 0.01. In addition, Fufang Haishe capsule inhibited the activity of caspase-9 and caspase-3 of PC-12 cells which was induced by Abeta. CONCLUSION: Fufang Haishe capsule significantly inhibite apoptosis of PC-12 cells induced by Abeta. The mechanism might be that Fufang Haishe capsule decrease the activity of the apoptosis implementing protein,caspase-9 and caspase-3.

[Investigation on sleep status of college and high school students].

OBJECTIVE: To investigate the sleep status of college and high schools students. METHODS: Pittsburgh sleep quality index (PSQI) and self-manufactured questionnaires about siesta habits were used as tools. Three groups of students from medical college (MC), senior high school (SS) and junior high school (JS) were surveyed. RESULTS: In the group MC, SS and JS, the occurrence rates of sleep disorders were 27%, 62% and 54%, respectively, and in which the appearance rates of insomnia were 17%, 19% and 19%, longing for sleep were 10%, 43% and 35% respectively. And there were no significant difference between schoolboy and schoolgirl. The occurrence rates of slack breathing were different (5/155, 1/154) significantly between group SS and JS. The distinct differences also were found in group JS and MC, in which students felt hot (10/155, 1/122) and in all the three groups, in which students felt sleepy (55/155, 62/154, 13/122) whereas the difference of sleepy between group SS and JS was comparatively distinct (55/155, 62/154). Significant differences were also found between group JS and SS, MC in average sleep time of (7.65 +/- 0.87) hours, (7.16 +/- 0.83) hours, and (7.10 +/- 0.57) hours. The time of falling asleep (median 15 min, 10 min, 20 min) and siesta habit (8/155, 19/154, 75/122) among group MC and SS, JS were different respectively and markedly, whereas siesta habit differences between group SS and JS were comparatively distinct (8/155, 19/154). CONCLUSION: Students in high school showed higher rate of longing for sleep, and this implicated they fall short of sleep time greatly and siesta could improve their sleepy signs.

[Inhibitory effect of sinomenine on expression of cyclooxygenase-2 in lipopolysaccharide-induced PC-12 cells].

OBJECTIVE: To study the effects of sinomenine (Sin) on cell proliferation, intracellular expression of cyclooxygenase-2 (COX-2), and production of PGE2 in lipopolysaccharide-induced PC-12 cells, To explore the Sin's mechanism on nerve cell. METHOD: PC-12 cells were cultured with nerve growing factors (NGF), and pretreated with Sin at various concentrations (0, 3 x 10(-6), 30 x 10(-6), 150 x 10(-6) mol x L(-1)) for 2 hours, then with or without stimulation of lipopolysaccharide (LPS). The proliferation activity of PC-12 cells was determined by 3H-TdR incorporation, and the production of PGE2 in culture supernatants of PC-12 cells was detected with competitive ELISA. Expression of COX-2 mRNA in PC-12 cells was analyzed by semi-quantitative RT-PCR, and expression of COX-2 protein was estimated by Western blot method and cellular enzyme immunoassay. Nuclear factor-kappa B (NF-kappaB) activity in whole-cell extract of PC-12 cells was also measured by an ELISA-based method. RESULT: The data showed that Sin down-regulated the expression of COX-2 mRNA and protein, and reduced the production of PGE2 in the LPS-stimulated PC-12 cells which correlated with Sin's concentrations positively. In addition, NF-kappaB activity in LPS-stimulated cells was suppressed significantly by Sin. No inhibition of proliferation of PC-12 cells due to Sin treatment was observed. CONCLUSION: Sin mediates the down-regulation of expression of COX-2 and production of induced PGE2 in PC-12 cells by suppressing the activity of NF-kappaB.