The role of gut microbiota in chronic restraint stress-induced cognitive deficits in mice

Background: Chronic stress induces cognitive deficits. There is a well-established connection between the enteric and central nervous systems through the microbiota-gut-brain (MGB) axis. However, the effects of the gut microbiota on cognitive deficits remain unclear. The present study aimed to elucidate the microbiota composition in cognitive deficits and explore its potential in predicting chronic stress-induced cognitive deficits. Methods: Mice were randomly divided into control and chronic restraint stress (CRS) groups. The mice subjected to CRS were further divided into cognitive deficit (CRS-CD) and non-cognitive deficit (CRS-NCD) groups using hierarchical cluster analysis of novel object recognition test results. The composition and diversity of the gut microbiota were analyzed. Results: After being subjected to chronic restraint distress, the CRS-CD mice travelled shorter movement distances (p = 0.034 vs. CRS-NCD; p < 0.001 vs. control) and had a lower recognition index than the CRS-NCD (p < 0.0001 vs. CRS-NCD; p < 0.0001 vs. control) and control mice. The results revealed that 5 gut bacteria at genus levels were significantly different in the fecal samples of mice in the three groups. Further analyses demonstrated that Muricomes were not only significantly enriched in the CRS-CD group but also correlated with a decreased cognitive index. The area under the receiver operating curve of Muricomes for CRS-induced cognitive deficits was 0.96. Conclusions: Our study indicates that the composition of the gut microbiota is involved in the development of cognitive deficits induced by chronic restraint stress. Further analysis revealed that Muricomes have the potential to predict the development of chronic stress-induced cognitive deficits in mice. Keywords: Gut microbiota, Chronic restraint stress, Cognitive deficits, Muricomes Mic

Longitudinal neural connection detection using a ferritin-encoding adeno-associated virus vector and in vivo MRI method

The investigation of neural circuits is important for interpreting both healthy brain function and psychiatric disorders. Currently, the architecture of neural circuits is always investigated with fluorescent protein encoding neurotropic virus and ex vivo fluorescent imaging technology. However, it is difficult to obtain a whole-brain neural circuit connection in living animals, due to the limited fluorescent imaging depth. Herein, the non-invasive, whole-brain imaging technique of MRI and the hypotoxicity virus vector AAV (adeno-associated virus) were combined to investigate the whole-brain neural circuits in vivo. AAV2-retro are an artificially-evolved virus vector that permits access to the terminal of neurons and retrograde transport to their cell bodies. By expressing the ferritin protein which could accumulate iron ions and influence the MRI contrast, the neurotropic virus can cause MRI signal changes in the infected regions. For mice injected with the ferritin-encoding virus vector (rAAV2-retro-CAG-Ferritin) in the caudate putamen (CPu), several regions showed significant changes in MRI contrasts, such as PFC (prefrontal cortex), HIP (hippocampus), Ins (insular cortex) and BLA (basolateral amygdala). The expression of ferritin in those regions were also verified with ex vivo fluorescence imaging. In addition, we demonstrated that changes in T2 relaxation time could be used to identify the spread area of the virus in the brain over time. Thus, the neural connections could be longitudinally detected with the in vivo MRI method. This novel technique could be utilized to observe the viral infection long-term and detect the neural circuits in a living animal. Keywords: Neural circuit; Ferritin; In vivo MRI; rAAV2-retro; Immunohistochemistry

Long-term micro-structure and cerebral blood flow changes in patients recovered from COVID-19 without neurological manifestations

The coronavirus disease 2019 (COVID-19) rapidly progressed to a global pandemic. Although patients totally recover from COVID-19 pneumonia, long-term effects on the brain still need to be explored. Here, two subtypes (mild type-MG and severe type-SG) with no specific neurological manifestations at the acute stage and no obvious lesions on the conventional MRI three months after discharge were recruited. Changes in gray matter morphometry, cerebral blood flow (CBF) and white matter (WM) microstructure were investigated using MRI. The relationship between brain imaging measurements and inflammation markers were further analyzed. Compared with healthy controls, the decrease in cortical thickness/CBF, and the changes in WM microstructure were observed to be more severe in the SG than MG, especially in the frontal and limbic systems. Furthermore, changes in brain microstructure, CBF and tracts parameters were significantly correlated with inflammatory markers. The indirect injury related to inflammatory storm may damage the brain, that led to these interesting observations. There are also other likely potential causes, such as hypoxemia and dysfunction of vascular endothelium, et al. The abnormalities in these brain areas need to be monitored in the process of complete recovery, which could help clinicians to understand the potential neurological sequelae of COVID-19. Key words: COVID-19; Brain MRI; Recovered patients; Inflammatory markers; Cortical thickness; Cerebral blood flow; microstructure; gray matter; white matter; subcortical nucle

Measuring changes in Schlemm’s canal and trabecular meshwork in different accommodation states in myopia children: an observational study

Abstract Purpose: Studies were designed to evaluate changes in the size of the Schlemm's Canal (SC) and trabecular meshwork(TM) during accommodation stimuli and cycloplegia states in myopic children. Methods: 34 children were enrolled. A -6D accommodation stimulus was achieved by looking at an optotype through a mirror. Cycloplegia state was induced with 1% tropicamide. Two states were confirmed by measuring the central lens thickness（CLT）, the anterior chamber depth and the pupil diameter. The size of the Schlemm's Canal (SC) and Trabecular Meshwork(TM) was measured using swept-source optical coherence tomography. And the associations between the change of the SC and the CLT were analyzed. Results: When compared with the relaxation state, under -6D accommodation stimuli, the size of SC increased significantly: the SC area (SCA) amplified from 6371±2517μm2 to 7824±2727 μm2; the SC length (SCL) from 249±10 μm to 295±12 μm, and SC width (SCW) from 27±9 μm to 31±8 μm. Under cycloplegia state, the SCA reduced to 5009±2028 μm2; the SCL to 212±μm and the SCW to 22±5 μm. In addition, the changed areas of SCA (r=0. 35; P=0.0007), SCL (r=0. 251; P=0.0172), and SCW (r=0. 253; P=0.016) were significantly correlated with the change in CLT. However, the size of TM did not change substantially when compared with the relaxation state. Only the TM length (TML) increased from 562±45μm to 587±47μm after -6D accommodation stimulus. Conclusion: SC size enlarges after -6D accommodation stimuli and shrinks under cycloplegia. However, for TM, only the TM length increase under accommodation stimulus state. KEYWORDS: Schlemm’s Canal, Trabecular Meshwork, accommodatio

Changes in work behavior during pregnancy in rural Anhui, China from 2001-03 to 2009:a population based cross-sectional study

BACKGROUND: In low- and middle-income countries, many women continue working later into pregnancy. In our recent study on some areas in rural China, most women stopped working already during the first trimester (≤3 months) of pregnancy. In this paper we aimed to explore whether stopping work during early pregnancy has changed over an 8 year period (between 2001-03 and 2009); we also studied whether the reasons for stopping work early were the same in the two time periods. METHODS: A population-based cross-sectional survey with a representative sample of new mothers was carried out in one rural county in Anhui Province in 2001-03 (N = 1479 respondents) and in two other rural counties in 2009 (N = 1574 respondents). Both surveys were used to evaluate prenatal care interventions not related to work behavior. The surveys targeted all women who had recently given birth. Multilevel logistic regression analysis was used to examine the determinants of work behavior in the two time periods. RESULTS: There was a big change in the working behavior between the two survey years: in the period 2001-03 6 % and in 2009, 53 % of pregnant women stopped working at ≤3 months (percentage change 839, 95 % CI -15.90 to 1694.49). In 2001-03, 30 % and in 2009, 23 % of pregnant women worked the same as before pregnancy (percentage change -22.30, 95 % CI -90.28 to 45.68). In both time periods women with two children were less likely to stop work at ≤3 months of pregnancy. Non-farmers were more likely in 2001-03 but less likely in 2009 to stop work at ≤3 months of pregnancy. Women with medium township-level income were more likely to maintain the same level of work as before pregnancy in 2001-03, while in 2009 women with high township-level income were less likely to work the same. CONCLUSION: Stopping work very early during pregnancy appeared to have become very common from 2001-3 to 2009 in rural Anhui, China and was not explained by women's background characteristicBioMed Central open acces

Non-pharmacological interventions for assisting the induction of anaesthesia in children

Publication status and date: New search for studies and content updated (no change to conclusions), published in Issue 7, 2015.Background: Induction of general anaesthesia can be distressing for children. Non‐pharmacological methods for reducing anxiety and improving co‐operation may avoid the adverse effects of preoperative sedation. Objectives: To assess the effects of non‐pharmacological interventions in assisting induction of anaesthesia in children by reducing their anxiety, distress or increasing their co‐operation. Search methods: In this updated review we searched CENTRAL (the Cochrane Library 2012, Issue 12) and searched the following databases from inception to 15 January 2013: MEDLINE, EMBASE, PsycINFO and Web of Science. We reran the search in August 2014. We will deal with the single study found to be of interest when we next update the review. Selection criteria: We included randomized controlled trials of a non‐pharmacological intervention implemented on the day of surgery or anaesthesia. Data collection and analysis: At least two review authors independently extracted data and assessed risk of bias in trials. Main results: We included 28 trials (2681 children) investigating 17 interventions of interest; all trials were conducted in high‐income countries. Overall we judged the trials to be at high risk of bias. Except for parental acupuncture (graded low), all other GRADE assessments of the primary outcomes of comparisons were very low, indicating a high degree of uncertainty about the overall findings. Parental presence: In five trials (557 children), parental presence at induction of anaesthesia did not reduce child anxiety compared with not having a parent present (standardized mean difference (SMD) 0.03, 95% confidence interval (CI) ‐0.14 to 0.20). In a further three trials (267 children) where we were unable to pool results, we found no clear differences in child anxiety, whether a parent was present or not. In a single trial, child anxiety showed no significant difference whether one or two parents were present, although parental anxiety was significantly reduced when both parents were present at the induction. Parental presence was significantly less effective than sedative premedication in reducing children's anxiety at induction in three trials with 254 children (we could not pool results). Child interventions (passive): When a video of the child's choice was played during induction, children were significantly less anxious than controls (median difference modified Yale Preoperative Anxiety Scale (mYPAS) 31.2, 95% CI 27.1 to 33.3) in a trial of 91 children. In another trial of 120 children, co‐operation at induction did not differ significantly when a video fairytale was played before induction. Children exposed to low sensory stimulation were significantly less anxious than control children on introduction of the anaesthesia mask and more likely to be co‐operative during induction in one trial of 70 children. Music therapy did not show a significant effect on children's anxiety in another trial of 51 children. Child interventions (mask introduction): We found no significant differences between a mask exposure intervention and control in a single trial of 103 children for child anxiety (risk ratio (RR) 0.59, 95% CI 0.31 to 1.11) although children did demonstrate significantly better co‐operation in the mask exposure group (RR 1.27, 95% CI 1.06 to 1.51). Child interventions (interactive): In a three‐arm trial of 168 children, preparation with interactive computer packages (in addition to parental presence) was more effective than verbal preparation, although differences between computer and cartoon preparation were not significant, and neither was cartoon preparation when compared with verbal preparation. Children given video games before induction were significantly less anxious at induction than those in the control group (mYPAS mean difference (MD) ‐9.80, 95% CI ‐19.42 to ‐0.18) and also when compared with children who were sedated with midazolam (mYPAS MD ‐12.20, 95% CI ‐21.82 to ‐2.58) in a trial of 112 children. When compared with parental presence only, clowns or clown doctors significantly lessened children's anxiety in the operating/induction room (mYPAS MD ‐24.41, 95% CI ‐38.43 to ‐10.48; random‐effects, I² 75%) in three trials with a total of 133 children. However, we saw no significant differences in child anxiety in the operating room between clowns/clown doctors and sedative premedication (mYPAS MD ‐9.67, 95% CI ‐21.14 to 1.80, random‐effects, I² 66%; 2 trials of 93 children). In a trial of hypnotherapy versus sedative premedication in 50 children, there were no significant differences in children's anxiety at induction (RR 0.59, 95% CI 0.33 to 1.04). Parental interventions: Children of parents having acupuncture compared with parental sham acupuncture were less anxious during induction (mYPAS MD ‐17, 95% CI ‐30.51 to ‐3.49) and were more co‐operative (RR 1.59, 95% CI 1.01 to 2.53) in a single trial of 67 children. Two trials with 191 parents assessed the effects of parental video viewing but did not report any of the review's prespecified primary outcomes. Authors' conclusions: This review shows that the presence of parents during induction of general anaesthesia does not diminish their child's anxiety. Potentially promising non‐pharmacological interventions such as parental acupuncture; clowns/clown doctors; playing videos of the child's choice during induction; low sensory stimulation; and hand‐held video games need further investigation in larger studies.Anne Manyande, Allan M Cyna, Peggy Yip, Cheryl Chooi, Philippa Middleto

Spinal voltage-gated potassium channel Kv1.3 contributes to neuropathic pain via promotion of microglial M1 polarization and activation of the NLRP3 inflammasome.

Background: Studies have shown that activation of microglia is the main mechanism of neuropathic pain. The Kv1.3 channel is a novel therapeutic target for treating neuroinflammatory disorders due to its crucial role in subsets of microglial cells. As such, it may be involved in the processes of neuropathic pain, however, whether Kv1.3 plays a role in neuroinflammation following peripheral nerve injury is unclear. Methods: The spared nerve injury model (SNI) was used to establish neuropathic pain. Western blot and immunofluorescence were used to examine the effect of Kv1.3 in the SNI rats. PAP-1, a Kv1.3 specific blocker was administered to alleviate neuropathic pain in the SNI rats. Results: Neuropathic pain and allodynia occurred after SNI, the levels of M1 (CD68, iNos) and M2 (CD206, Arg-1) phenotypes were up-regulated in the spinal cord, and the protein levels of NLRP3, caspase-1 and IL-1β were also increased. Pharmacological blocking of Kv1.3 with PAP-1 alleviated hyperpathia induced by SNI. Meanwhile, intrathecal injection of PAP-1 reduced M1 polarization and decreased NLRP3, caspase-1, and IL-1β expressions of protein levels. Conclusion: Our research indicates that the Kv1.3 channel in the spinal cord contributes to neuropathic pain by promoting microglial M1 polarization and activating the NLRP3 inflammasome

The role of gut microbiota in diabetic peripheral neuropathy rats with cognitive dysfunction

Abstract Owing to advancements in non-invasive magnetic resonance imaging, many studies have repeatedly showed that diabetes affects the central nervous system in the presence of peripheral neuropathy, suggesting a common or interacting pathological mechanism for both complications. We aimed to investigate the role of abnormal gut microbiota in rats with diabetic peripheral neuropathy (DPN) combined with cognitive dysfunction. Glucose-compliant rats with nerve conduction deficits were screened as a successful group of DPN rats. The DPN group was then divided into rats with combined cognitive impairment (CD) and rats with normal cognitive function (NCD) based on the results of the Novel object recognition test. Rat faeces were then collected for 16S rRNA gene sequencing of the intestinal flora. The results revealed that abnormalities in Firmicutes, Ruminococcaceae, Bacteroidia, and Actinobacteria-like microorganisms may induce DPN complicated by cognitive dysfunction. Keywords: diabetic periphery neuropathy; gut microbiota

Neuronal mechanisms of adenosine A2A receptors in the loss of consciousness induced by propofol general anesthesia with functional magnetic resonance imaging

Propofol is the most common intravenous anesthetic agent for induction and maintenance of anesthesia and has been used clinically for more than 30 years. However, the mechanism by which propofol induces loss of consciousness (LOC) remains largely unknown. The adenosine A2A receptor (A2AR) has been extensively proven to have an effect on physiological sleep. It is, therefore, important to investigate the role of A2AR in the induction of LOC using propofol. In the present study, the administration of the highly selective A2AR agonist (CGS21680) and antagonist (SCH58261) was utilized to investigate the function of A2AR under general anesthesia induced by propofol by means of animal behavior studies, resting‐state magnetic resonance imaging and c‐Fos immunofluorescence staining approaches. Our results show that CGS21680 significantly prolonged the duration of LOC induced by propofol, increased the c‐Fos expression in nucleus accumbens (NAc) and suppressed the functional connectivity of NAc‐dorsal raphe nucleus (DR) and NAc‐cingulate cortex (CG). However, SCH58261 significantly shortened the duration of LOC induced by propofol, decreased the c‐Fos expression in NAc, increased the c‐Fos expression in DR, and elevated the functional connectivity of NAc‐DR and NAc‐CG. Collectively, our findings demonstrate the important roles played by A2AR in the LOC induced by propofol and suggest that the neural circuit between NAc‐DR maybe controlled by A2AR in the mechanism of anesthesia induced by propofol