The microaerophilic microbiota of de-novo paediatric inflammatory bowel disease: the BISCUIT study

<p>Introduction: Children presenting for the first time with inflammatory bowel disease (IBD) offer a unique opportunity to study aetiological agents before the confounders of treatment. Microaerophilic bacteria can exploit the ecological niche of the intestinal epithelium; Helicobacter and Campylobacter are previously implicated in IBD pathogenesis. We set out to study these and other microaerophilic bacteria in de-novo paediatric IBD.</p> <p>Patients and Methods: 100 children undergoing colonoscopy were recruited including 44 treatment naïve de-novo IBD patients and 42 with normal colons. Colonic biopsies were subjected to microaerophilic culture with Gram-negative isolates then identified by sequencing. Biopsies were also PCR screened for the specific microaerophilic bacterial groups: Helicobacteraceae, Campylobacteraceae and Sutterella wadsworthensis.</p> <p>Results: 129 Gram-negative microaerophilic bacterial isolates were identified from 10 genera. The most frequently cultured was S. wadsworthensis (32 distinct isolates). Unusual Campylobacter were isolated from 8 subjects (including 3 C. concisus, 1 C. curvus, 1 C. lari, 1 C. rectus, 3 C. showae). No Helicobacter were cultured. When comparing IBD vs. normal colon control by PCR the prevalence figures were not significantly different (Helicobacter 11% vs. 12%, p = 1.00; Campylobacter 75% vs. 76%, p = 1.00; S. wadsworthensis 82% vs. 71%, p = 0.312).</p> <p>Conclusions: This study offers a comprehensive overview of the microaerophilic microbiota of the paediatric colon including at IBD onset. Campylobacter appear to be surprisingly common, are not more strongly associated with IBD and can be isolated from around 8% of paediatric colonic biopsies. S. wadsworthensis appears to be a common commensal. Helicobacter species are relatively rare in the paediatric colon.</p&gt

Dopaminergic Regulation of Nucleus Accumbens Cholinergic Interneurons Demarcates Susceptibility to Cocaine Addiction

Background: Cholinergic interneurons (ChINs) in the nucleus accumbens (NAc) play critical roles in processing information related to reward. However, the contribution of ChINs to the emergence of addiction-like behaviors and its underlying molecular mechanisms remain elusive. Methods: We employed cocaine self-administration to identify two mouse subpopulations: susceptible and resilient to cocaine seeking. We compared the subpopulations for physiological responses with single-unit recording of NAc ChINs, and for gene expression levels with RNA sequencing of ChINs sorted using fluorescence-activated cell sorting. To provide evidence for a causal relationship, we manipulated the expression level of dopamine D2 receptor (DRD2) in ChINs in a cell type–specific manner. Using optogenetic activation combined with a double whole-cell recording, the effect of ChIN-specific DRD2 manipulation on each synaptic input was assessed in NAc medium spiny neurons in a pathway-specific manner. Results: Susceptible mice showed higher levels of nosepoke responses under a progressive ratio schedule, and impairment in extinction and punishment procedures. DRD2 was highly abundant in the NAc ChINs of susceptible mice. Elevated abundance of DRD2 in NAc ChINs was sufficient and necessary to express high cocaine motivation, putatively through reduction of ChIN activity during cocaine exposure. DRD2 overexpression in ChINs mimicked cocaine-induced effects on the dendritic spine density and the ratios of excitatory inputs between two distinct medium spiny neuron cell types, while DRD2 depletion precluded cocaine-induced synaptic plasticity. Conclusions: These findings provide a molecular mechanism for dopaminergic control of NAc ChINs that can control the susceptibility to cocaine-seeking behavior. © 2020 Society of Biological Psychiatry1

Chronic Corticosterone Exposure Persistently Elevates the Expression of Memory-Related Genes in the Lateral Amygdala and Enhances the Consolidation of a Pavlovian Fear Memory

<div><p>Chronic exposure to stress has been widely implicated in the development of anxiety disorders, yet relatively little is known about the long-term effects of chronic stress on amygdala-dependent memory formation. Here, we examined the effects of a history of chronic exposure to the stress-associated adrenal steroid corticosterone (CORT) on the consolidation of a fear memory and the expression of memory-related immediate early genes (IEGs) in the lateral nucleus of the amygdala (LA). Rats received chronic exposure to CORT (50 μg/ml) in their drinking water for 2 weeks and were then titrated off the CORT for an additional 6 days followed by a 2 week ‘wash-out’ period consisting of access to plain water. Rats were then either sacrificed to examine the expression of memory-related IEG expression in the LA or given auditory Pavlovian fear conditioning. We show that chronic exposure to CORT leads to a persistent elevation in the expression of the IEGs Arc/Arg3.1 and Egr-1 in the LA. Further, we show that rats with a history of chronic CORT exposure exhibit enhanced consolidation of a fear memory; short-term memory (STM) is not affected, while long-term memory (LTM) is significantly enhanced. Treatment with the selective serotonin reuptake inhibitor (SSRI) fluoxetine following the chronic CORT exposure period was observed to effectively reverse both the persistent CORT-related increases in memory-related IEG expression in the LA and the CORT-related enhancement in fear memory consolidation. Our findings suggest that chronic exposure to CORT can regulate memory-related IEG expression and fear memory consolidation processes in the LA in a long-lasting manner and that treatment with fluoxetine can reverse these effects.</p></div

Fluoxetine treatment following chronic CORT exposure reverses the CORT-induced enhancement of fear memory consolidation.

<p>(<b>A</b>) Schematic of the behavioral protocol. Rats received either Water (n = 7) or CORT (n = 7; 50 μg/ml) for 2 weeks followed by CORT titration (25 μg/ml, 12.5 μg/ml). Rats then received 3 weeks of either Water (n = 6) or fluoxetine (FLX; n = 7; 333 μg/ml). At the end of the fluoxetine exposure period, rats were tested in the elevated plus maze (EPM). Rats were then fear conditioned with 2 tone-shock pairings and tested for STM (2 hr later) and LTM (24 hr later). (<b>B</b>) Mean (±SEM) time spent exploring the open and closed arms of the EPM in each group. (<b>C</b>) Mean (±SEM) post-shock freezing scores in each group following each conditioning trial. (<b>D</b>) Mean (±SEM) STM scores across each trial in each group. (<b>E</b>) Mean (±SEM) LTM scores across each trial in each group.</p

Chronic exposure to CORT persistently enhances the expression of memory-related IEGs and synaptically-localized proteins in the LA.

<p>(<b>A</b>) Schematic of the behavioral protocol. Rats received either Water or CORT in their drinking water (50 μg/ml) for 2 weeks. Half the rats were sacrificed at the end of CORT exposure period. The other half was titrated off the CORT (25 μg/ml, 12.5 μg/ml) and given a 2 week period of exposure to water alone (‘wash-out’) prior to being sacrificed. (<b>B</b>) Mean (±SEM) immunoreactivity for GluR1, synaptophysin and BDNF (Water: n = 9; CORT: n = 9) from area CA3 in rats sacrificed on the last day of CORT exposure. (<b>C</b>) Mean (±SEM) immunoreactivity for GluR1 (Water: n = 9; CORT: n = 9), synaptophysin (Water: n = 9; CORT: n = 9), Arc/Arg3.1 (Water: n = 9; CORT: n = 9), Egr-1 (Water: n = 9; CORT: n = 9), BDNF (Water: n = 9; CORT: n = 9), acetyl-H3 (Water: n = 7; CORT: n = 9), phospho-ERK 1 and phospho-ERK 2 (Water: n = 8; CORT: n = 9) from the LA in rats sacrificed on the last day of CORT exposure. (<b>D</b>) Representative Western blots for each protein in (C). (<b>E</b>) Mean (±SEM) immunoreactivity for GluR1, synaptophysin, and BDNF (Water: n = 9; CORT: n = 9) from area CA3 in rats sacrificed on the last day of the wash-out period. (<b>F</b>) Mean (±SEM) immunoreactivity for GluR1 (Water: n = 9; CORT: n = 8), synaptophysin (Water: n = 9; CORT: n = 9), Arc/Arg3.1 (Water: n = 9; CORT: n = 8), Egr-1 (Water: n = 9; CORT: n = 8), BDNF (Water: n = 9; CORT: n = 9), acetyl-H3 (Water: n = 9; CORT: n = 8), phospho-ERK 1 and phospho-ERK 2 (Water: n = 9; CORT: n = 8) from the LA in rats sacrificed on the last day of the wash-out period. (<b>G</b>) Representative Western blots for each protein in (F). For each experiment, protein levels have been normalized to GAPDH levels for each sample and expressed as a percentage of the Water group. (*) <i>p</i> < 0.05 relative to Water group.</p

Sex-Specific Role for the Long Non-coding RNA LINC00473 in Depression

Depression is a common disorder that affects women at twice the rate of men. Here we report that long non-coding RNAs (lncRNAs), a recently discovered class of regulatory transcripts, represent about one-third of the differentially expressed genes in the brains of depressed humans, and display complex region- and sex-specific patterns of regulation. We identified the primate-specific, neuronal-enriched gene, LINC00473, as downregulated in prefrontal cortex (PFC) of depressed females but not males. Using viral-mediated gene transfer to express LINC00473 in adult mouse PFC neurons, we mirrored the human sex-specific phenotype by inducing stress resilience solely in female mice. This sex-specific phenotype was accompanied by changes in synaptic function and gene expression selectively in female mice and, along with studies of human neuron-like cells in culture, implicates LINC00473 as a CREB effector. Together, our studies identify LINC00473 as a female-specific driver of stress resilience that is aberrant in female depression