C57BL6 Mice Research Articles

Suppression of certain intestinal microbiota metabolites may lead to gestational diabetes in mice fed a high-fat diet.

We aim to establish a gestational diabetes mellitus (GDM) mouse model with mice fed with a high-fat diet (HFD) in comparison with pregnant mice with normal blood glucose levels to investigate the role of intestinal microbiota in the development of HFD-induced GDM. We divided healthy 6-week-old female C57BL mice into an HFD-induced GDM group and a normal diet group. Their bacterial flora and metabolites in intestinal fecal exosomes were co-analyzed using 16 s multi-region sequencing and compared. Alpha (α) diversity was lower within the model group compared to the control group. Beta (β) diversity was significantly different between the two groups. The relative abundances of Lactobacillus, Actinomyces, Rothia, and Bacteroidetes were significantly different between the two groups. Fermentation and nitrate consumption were significantly higher in the GDM group. Multiple bacteria were associated with glycerophosphocholine, S-methyl-5'-thioadenosine, quinolinate, galactinol, deoxyadenosine, DL-arginine, and 2-oxoadenic acid. Imbalances in the production of Lactobacillus, Bacteroidetes, Actinomyces, and Rothia and their related metabolites may lead to metabolic disturbances in GDM. These indicators may be used to assess changes affecting the intestinal microbiota during pregnancy and thus help modulate diet and alter blood glucose.

Dynamic Pathology of Enteric Neural Network using Curcumin-assisted Multiphoton Laser Imaging in Hirschsprung Disease.

In living tissue, it has been difficult to make microscopic-level observations without damaging the tissue. We have invented a novel intravital fluorescent observation method (IFOM) for real-time tissue observation, combining multi-photon laser scanning microscopy (MPLSM) with curcumin vital staining (CVS-IFOM). The aim of this study was to use CVS-IFOM to analyze the enteric nervous system (ENS) in mice and human patients with hypoganglionosis and Hirschsprung disease. In an initial viability study, we compared live ENS images from non-fluorescent C57BL6 mice stained with curcumin (n=5) and GFP mice (n=5) using MPLSM. We then explored CVS-IFOM for the live examination of resected colon tissues from one hypoganglionosis and three Hirschsprung disease patients. In the viability study, detailed ENS histological features were only observed in the curcumin-stained mice. In the hypoganglionosis patient, CVS-IFOM provided ENS details that were not visualized under H&E staining or calretinin immunohistochemistry, allowing the analysis of ENS size, neural bundle number, and neural cell number per plexus. In Hirschsprung disease patients, CVS-IFOM showed a gradual hypoplastic change in the ENS from the oral wedge to the anal wedge, detecting disproportionate changes in the ENS within the same intestinal level, supporting a circumferentially uneven distribution of the intestinal ENS. CVS-IFOM may be supportive for intraoperative pathological diagnosis during surgeries in Hirschsprung disease.

CCR5-mediated homing of regulatory T cells and monocytic-myeloid derived suppressor cells to dysfunctional endothelium contributes to early atherosclerosis.

A disbalance between immune regulatory cells and inflammatory cells is known to drive atherosclerosis. However, the exact mechanism is not clear. Here, we investigated the homing of immune regulatory cells, mainly, regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) subsets in asymptomatic coronary artery disease (CAD) risk factor-exposed young individuals (dyslipidemia [DLP] group) and stable CAD patients (CAD group). Compared with healthy controls (HCs), Tregs frequency was reduced in both DLP and CAD groups but expressed high levels of CCR5 in both groups. The frequency of monocytic-myeloid-derived suppressor cells (M-MDSCs) was increased while polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) were decreased in CAD patients only. Interestingly, although unchanged in frequency, M-MDSCs of the DLP group expressed high levels of CCR5. Serum levels of chemokines (CCL5, CX3CL1, CCL26) and inflammatory cytokines (IL-6, IL-1β, IFN-γ, TNF-α) were higher in the DLP group. Stimulation with inflammatory cytokines augmented CCR5 expression in Tregs and M-MDSCs isolated from HCs. Activated endothelial cells showed elevated levels of CX3CL1 and CCL5 in vitro. Blocking CCR5 with D-Ala-peptide T-amide (DAPTA) increased Treg and M-MDSC frequency in C57Bl6 mice fed a high-fat diet. In accelerated atherosclerosis model, DAPTA treatment led to the formation of smooth muscle-rich plaque with less macrophages. Thus, we show that CCR5-CCL5 axis is instrumental in recruiting Tregs and M-MDSCs to dysfunctional endothelium in the asymptomatic phase of atherosclerosis contributing to atherosclerosis progression. Drugs targeting CCR5 in asymptomatic and CAD risk-factor/s-exposed individuals might be a novel therapeutic regime to diminish atherogenesis.

Terminalia bellirica (Gaertn.) Roxb. Extracts reshape the perifollicular microenvironment and regulate the MAPK pathway for androgenetic alopecia treatment

Ethnopharmacological relevanceTerminalia bellirica (Gaertn.) Roxb. (TBR), a popular herbal remedy in India and Southeast Asia, has been demonstrated to possess multiple pharmacological activities. However, systematic studies on the medicinal effects and mechanism of TBR for the androgenetic alopecia (AGA) treatment are deficient. Materials and methodsHuman Umbilical Vein Endothelial Cells (HUVECs) and testosterone-induced AGA mice were used to evaluate the hair regrowth activity of TBR extracts. Chemical constituents and potential active components of TBR extracts were analyed by UPLC-Q-TOF-MS in vitro/vivo. The hair regrowth mechanisms of TBR were elucidated through network pharmacology and experimental validation. ResultsTotally 28 chemical constituents in TBR were identified, of which 15 were predicted as potential active components for AGA therapy. TBR could significantly scavenge ROS, promote VEGF level/cell migration of HUVECs, and inhibiting type II 5α-reductase activity (the inhibit rate: 82.35 ± 1.02 %). Pharmacodynamic evaluation suggested that TBR effectively led to hair regrowth in C57BL6 mice compared to minoxidil. TBR promoted the hair follicle (HF) transition from the telogen phase to anagen phase by decreasing MDA levels, increasing VEFG expression and up-regulating phosphorylated P38/ERK protein levels in the MAPK signalling pathway. ConclusionsTBR reversed AGA via inhibiting SRD5A2 activity and stimulating the MAPK pathway. Meantime, TBR could remodel the follicle microenvironment by reducing oxidative stress and increasing angiogenesis.

Voluntary exercise suppresses inflammation and improves insulin resistance in the arcuate nucleus and ventral tegmental area in mice on a high-fat diet

A high-fat diet (HFD) causes inflammation with an increase in microglial activity in the hypothalamic arcuate nucleus (ARC) and ventral tegmental area (VTA), resulting in insulin resistance in both regions. This leads to a deterioration in glucose and energy metabolism. The effect of voluntary exercise on HFD-induced inflammation in the central nervous system (CNS) remains unclear. To clarify the effects of voluntary exercise on the CNS, 8-week-old male C57BL6 mice were fed a chow diet (CHD) or HFD for 4 weeks; each group was further divided into running exercise (EX+) on a wheel and no exercise (EX-) groups. The expression of the inflammatory cytokine, tumor necrosis factor alpha (TNFα), in the ARC and VTA was significantly increased in the HFD/EX- group, with an increase of microglial activity noted, compared to the CHD/EX- group. The expression of TNFα was significantly suppressed, with a decrease of microglial activity, in the HFD/EX+ compared to HFD/EX- group. Insulin resistance in the ARC and VTA was improved with the suppression of TNFα expression. The HFD/EX- group showed significant weight gain and impaired glucose metabolism compared to the CHD/EX- group. The HFD/EX+ group showed an improvement in glucose and energy metabolism compared to the HFD/EX- group. In addition, voluntary wheel running suppressed HFD-induced inflammation in the ARC, with a decrease in microglial activity observed independently of weight changes. Our data suggest that voluntary exercise prevents obesity and improves glucose metabolism by suppressing inflammation in the ARC and VTA under HFD conditions.

Abstract MP03: Perineuronal nets in the paraventricular nucleus of the hypothalamus are altered during DOCA-salt hypertension

The paraventricular nucleus of the hypothalamus (PVN) is critical to integrate peripheral signals to modulate neurohumoral and sympathetic output. During hypertension, overactivation of the PVN contributes to neurohumoral dysregulation and increased sympathetic tone. Perineuronal nets (PNNs) are lattice-like extracellular structures that surround the soma and proximal dendrites of neurons and modulate neuronal firing and circuit plasticity. These structures are expressed throughout the brain, including the hypothalamus and PVN, and are of particular interest because changes in their deposition have been associated with multiple neurological disorders including stress, PTSD, and depression. Here, we explore changes in PNNs in the PVN during DOCA-salt hypertension, a model of neurogenic hypertension, specifically testing the hypothesis that PNNs deposition would be decreased in the PVN. 5-month old male C57BL6 mice were implanted with a s.c. deoxycorticosterone acetate (DOCA) pellet and received 0.9% NaCl in the drinking water. Blood pressure was monitored twice weekly by tail-cuff plethysmography. After 21-days of DOCA-salt (n=3) and sham control (n=4), mice were perfused with 2% paraformaldehyde to quantify PNNs using the marker N-acetylgalactosamine-binding Wisteria floribunda agglutinin (WFA). We found a trend towards less WFA+ neurons in the PVN in DOCA-salt vs control (42.29 ± 7.93 neurons/mm 2 in DOCA vs 68.97 ± 10.80 in control; p=0.1231), but observed no difference in the overall PVN area that was positive for WFA+ staining (26.53 ±0.80 % in DOCA vs 29.75 ± 2.02 % in control). Next, we quantified WFA intensity (PMID 28713865) and observed a decrease in individual PNN intensity in the PVN of DOCA-salt mice (40.08 ± 7.46 vs 67.39 ± 7.42 a.u. in control), as well as a decrease in total WFA+ intensity in the PVN (26.04 ± 3.48 vs 33.80 ± 0.29 a.u. in control; p=0.0458). We conclude that PNN deposition is decreased in the PVN during DOCA-salt hypertension, a potentially important mechanism which has been previously unexplored. PNN intensity has been previously associated with neuronal firing; therefore, ongoing studies are investigating the contribution of PNNs in the PVN to sympathetic tone and blood pressure regulation during DOCA-salt hypertension.

Abstract 23: Cognitive impairment during chronic i.c.v. angiotensin II is associated with increased tau phosphorylation in the cortex and hippocampus

Cardiovascular risk factors, such as hypertension, are recognized as important contributors to cognitive impairment and dementia, including Alzheimer’s disease (AD). However, the mechanisms underlying the detrimental effects of hypertension on the brain remain to be fully established. Angiotensin II (Ang II) has known detrimental effects on the brain, including cerebrovascular damage, sympathetic activation, and neuroinflammation. Ang II activates neuronal glycogen synthase 3b (GSK-3b), a major kinase involved in the phosphorylation of the microtubule associated protein tau. Hyperphosphorylated tau and the subsequent formation of neurofibrillary tangles are a hallmark of AD and related dementias (tauopathies). Here, we tested the central hypothesis that brain Ang II leads to cognitive impairment by increasing tau hyperphosphorylation. 3-month old male C57BL6 mice were implanted with a s.c. osmotic minipump connected to an i.c.v. cannula delivering low dose Ang II (6ng/hr) or saline for 4 weeks. Blood pressure was monitored twice weekly using tail-cuff plethysmography. During the 4 th week of infusion, mice underwent a battery of neurobehavioral testing assessing various cognitive domains including novel object recognition (recognition and short-term memory), Y-maze (spatial working memory), Barnes maze (spatial learning and long-term memory), and hippocampal/executive function (nest building). Tau phosphorylation was assessed in the cortex and hippocampus by Western blotting. Systolic blood pressure increased slightly by week 3 prior to start of behavioral tests (control: 115.3 ± 4.1 mmHg vs Ang II: 130.8 ± 4.7; n=10). We did not observe significant differences during novel object recognition (discrimination index: control: 0.49 ± 0.08 vs Ang II: 0.35 ± 0.23; n=5) or Y-maze (spontaneous alternations: control: 62.4 ± 6.1% vs Ang II: 59.0 ± 4.3%). Mice receiving i.c.v. Ang II had significantly delayed latency to find the escape hole during the Barnes maze learning trials (Treatment p=0.0006, Time p=0.0039, interaction: p=0.3028; two-way repeated measures ANOVA). The impairment in spatial learning was associated with an increase in tau phosphorylation in the cortex assessed by AT8 antibody. Ongoing studies are investigating whether this increase is mediated by activation of neuronal GSK-3b. We conclude that Ang II-mediated hyperphosphorylation of tau is a potential novel molecular mechanism driving the detrimental effects of hypertension on cognitive health.

P098 CARDIAC REMODELING IN MICE TREATED WITH SODIUM OXALATE AND AORTIC STENOSIS

Background: Cardiovascular Diseases are one of the main global public health problems, with increasing mortality due to population aging and Hypertension (HTN). HTN is a risk factor for other diseases, such as aortic stenosis, renal dysfunction, and cardiac hypertrophy (CH). The hemodynamic overload caused by HTN affects the heart and kidneys, but the exact mechanisms of these alterations are not fully understood. Experimental models help study these mechanisms; however, a well-established model of CH with cardiorenal dysfunction does not yet exist. Objective: to evaluate whether the combination of cardiac hypertrophy, induced by transverse aortic constriction (TAC), and renal injury, induced by soluble sodium oxalate (OXA), can be a new model of CH with cardiorenal dysfunction. Methods: Male C57BL mice were randomized as follows: SHAM, receiving saline or OXA solution, and TAC, receiving saline or OXA solution. Echocardiography, direct blood pressure (BP) recording, metabolic cage, histology were performed to evaluate cardiac and renal function, hemodynamics, autonomic modulation, and baroreflex. Results: The TAC+OXA group showed the highest systolic BP(SBP) (SBP: SHAM: 122±5.24 vs. TAC+OXA: 160±5.24 mmHg, p<0.01), increased double product (DP) (DP: SHAM: 64.65±4.76 mmHg/bpm vs. TAC: 89.53±5.85 mmHg/bpm, p=0.02), significant reduction in autonomic modulation (RMSSD: OXA: 12.5±1.8 vs. TAC+OXA: 2.8±0.2 ms, p<0.01) and reflex tachycardia, eccentric hypertrophy, and worse renal function. The TAC group showed eccentric hypertrophy, increased BP variability (SD-SBP: SHAM: 2.97±0.07 mmHg vs. TAC: 5.63±0.57 mmHg, p≤0.01), diastolic dysfunction, and dilated left ventricle in diastole. The OXA group showed increased autonomic modulation and heart rate variability, renal damage characterized by inflammation, proximal tubule damage, and interstitial fibrosis when associated with TAC. All treated groups showed a significant reduction in reflex tachycardia. Conclusion: Transverse aortic constriction combined with OXA gavage is a model of CH with renal dysfunction, as the combination caused more significant renal damage, systemic hypertension, decreased autonomic modulation and baroreflex sensitivity, and eccentric hypertrophy with subsequent LV diastolic dysfunction.

γ-Aminobutyric acid alleviates litchi thaumatin-like protein-induced inflammation and reduces gut microbial translocation

Previous research reported litchi thaumatin-like protein (LcTLP) could lead to inflammation, which is a factor causing the adverse reactions after excessive intake of litchi. As a main amino acid in litchi pulp, γ-aminobutyric acid (GABA) was found with anti-inflammatory effect. Therefore, this study aimed to investigate the effects of GABA on LcTLP-induced inflammation through RAW264.7 macrophages and C57BL mice models. In vitro study showed GABA could effectively regulate the level of inflammatory cytokines (interleukin (IL)-1β, IL-6, IL-10, and prostaglandin E2) and Ca2+ in cells, and inhibit the phosphorylation of p65, IκB, p38, c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK). These results indicate GABA alleviated inflammation through nuclear factor-κB and mitogen-activated protein kinase pathways signaling pathways. In vivo experiment was performed to verify the anti-inflammatory effect of GABA, and the results demonstrated that GABA reduced the inflammation and oxidative stress in the liver of LcTLP-treated mice, as it down-regulated the pro-inflammatory cytokines, malondialdehyde, aspartate transferase, and alanine transaminase. The relative expression of phosphorylated p38, JNK and ERK in mice liver with GABA treatment were reduced to 65 %, 39 % and 80 % of the control group, respectively. Furthermore, GABA treatment enriched probiotic bacteria and decreased pathogenic bacteria in mice gut, which reveals GABA could effectively reduce the translocation of gut microbiota.

Parkin deficiency exacerbates particulate matter-induced injury by enhancing airway epithelial necroptosis

Exposure to fine particulate matter (PM) disrupts the function of airway epithelial barriers causing cellular stress and damage. However, the precise mechanisms underlying PM-induced cellular injury and the associated molecular pathways remain incompletely understood. In this study, we used intratracheal instillation of PM in C57BL6 mice and PM treatment of the BEAS-2B cell line as in vivo and in vitro models, respectively, to simulate PM-induced cellular damage and inflammation. We collected lung tissues and bronchoalveolar lavage fluids to assess histopathological changes, necroptosis, and airway inflammation. Our findings reveal that PM exposure induces necroptosis in mouse airway epithelial cells. Importantly, concurrent administration of a receptor interacting protein kinases 3 (RIPK3) inhibitor or the deletion of the necroptosis effector mixed-lineage kinase domain-like protein (MLKL) effectively attenuated PM-induced airway inflammation. PM exposure dose-dependently induces the expression of Parkin, an E3 ligase we recently reported to play a pivotal role in necroptosis through regulating necrosome formation. Significantly, deletion of endogenous Parkin exacerbates inflammation by enhancing epithelial necroptosis. These results indicate that PM-induced Parkin expression plays a crucial role in suppressing epithelial necroptosis, thereby reducing airway inflammation. Overall, these findings offer valuable mechanistic insights into PM-induced airway injury and identify a potential target for clinical intervention.

Evidence of Increase in the Oxidative Stress in C57BL Mice Subjected to Daily Diacetyl Treatment: Oxidative Stress in Mice Subjected to Diacetyl Treatment

Evidence of Increase in the Oxidative Stress in C57BL Mice Subjected to Daily Diacetyl Treatment: Oxidative Stress in Mice Subjected to Diacetyl Treatment

Morinda Officinalis Polysaccharides Inhibit Osteoclast Differentiation by Regulating miR-214-3p/NEDD4L in Postmenopausal Osteoporosis Mice

To investigate the potential mechanism of Morinda officinalis F. C. How polysaccharides (MOPs) in regulating osteoclast differentiation and apoptosis through miR-214-3p and its target protein. Ovariectomy was performed in 8-week female C57BL6 mice to establish the postmenopausal osteoporosis (PMOP) model. Mice were treated immediately with 500 mg/kg of MOPs (prevention group); others were treated 2 weeks after operation (treatment group). Left femur bone mineral density (BMD) was examined. RAW264.7 cells were administered with receptor activator of NF-κB ligand (RANKL) to establish the osteoclast (OC) model and treated with serum containing 1 or 2 g/kg of MOPs. Apoptosis-related indexes, miR-214-3p, and Expressed Developmentally Down-regulated 4-Like (NEDD4L) were detected by western blot, quantitative real-time-reverse transcription polymerase chain reaction (qRT-PCR), and flow cytometry. OC received a miR-214-3p inhibitor or NEDD4L small interfering RNA (siRNA). MOPs reversed the PMOP-induced changes in bones. Compared with the RANKL group, MOPs increased the apoptosis and related markers in OCs. MOPs decreased the femur miR-214-3p of PMOP mice (P < 0.001). Higher concentrations of MOPs reversed the upregulation of miR-214 mRNA in OCs (P < 0.001). miR-214-3p inhibitor increased the expression of Bax and CC3 (P < 0.01) and decreased the expression of Bcl-2 (P < 0.05). NEDD4L is targeted by miR-214. NEDD4L was upregulated in the RANKL + MOPs group (P < 0.01). miR-214-3p inhibitor increased the upregulation of NEDD4L induced by MOPs (P < 0.05). siRNA NEDD4L significantly reversed the inhibition of MOPs on osteoclast differentiation with miR-214-3p inhibitor (P < 0.01). MOPs effectively prevent PMOP by inhibiting osteoclastogenesis and inducing OC apoptosis through the miR-214-3p/NEDD4L pathway.

Blood glucose and β-hydroxybutyrate predict significant brain injury after hypoxia-ischemia in neonatal mice.

The Vannucci procedure is widely used to model cerebral hypoxic-ischemic (HI) injury in neonatal rodents. Identifying minimally invasive biomarkers linked to brain injury would improve stratification of pups to experimental treatments. We hypothesized that extreme blood glucose (BG) and β-hydroxybutyrate (bHB) levels immediately after HI will correlate with severity of brain injury in this model. C57BL6 mice of both sexes underwent the Vannucci procedure with BG and bHB measured immediately after hypoxia. GFAP and α-fodrin were measured to assess injury severity at 4h, P11, P18 and P40. Open field (OF), Y-maze (YM), and Object-location task (OLT) were tested at P40. Clinical seizures-like stereotypies during hypoxia were associated with lower post-hypoxia BG in HI-injured mice. Low BG after HI was related to higher GFAP expression, higher α-fodrin breakdown, lower residual regional volume, and worse working memory. BG was superior to bHB in ROC analysis with BG threshold of <111 mg/dL providing 100% specificity with 72% sensitivityfor hippocampal HI-injury. Post-hypoxic BG is a minimally invasive screening tool to identify pups with significant HI brain injury in the Vannucci model modified for mice improving our ability to stratify pups to experimental treatments to assess effectiveness. End hypoxic-ischemic blood glucose levels are a reliable and inexpensive biomarker to detect hypoxic-ischemic brain injury in mice. Screening with blood glucose levels post-hypoxia allows appropriate stratification of those mouse pups most likely to be injured to experimental treatments improving validity and translatability of the results. These findings provide biological plausibility to the clinical observation that extreme blood glucose levels relate to worse outcomes after hypoxia-ischemia.

Respiratory dysfunction in old mice could be related to inflammation and lung fibrosis induced by hyperphosphatemia.

With age, lungs undergo typical changes that lead to a deterioration of respiratory function. Our aim was to assess the role of age-associated hyperphosphatemia in these changes. We used C57BL6 mice to study an ageing model invivo and human lung fibroblasts were treated with a phosphate donor, beta-glycerophosphate (BGP), to explore mechanisms involved. Respiratory function was registered with a double chamber plethysmograph. Lung structure was analysed by different staining, phosphate and cytokines levels by colorimeric kits, expression of fibrosis, inflammation and ET-1 system by western blot or RT-PCR. Old mice showed hyperphosphatemia, along with lung fibrosis, loss of elastin, increased expression of pro-inflammatory cytokines and impaired respiratory function. BGP induced inflammation and fibrosis in fibroblasts through the activation and binding of NFkB to the MCP-1 or FN promoters. BGP increased ECE-1 expression by inducing NFkB binding to the ECE-1 promoter. QNZ, an NFkB inhibitor, blocked these effects. When ECE-1 was inhibited with phosphoramidon, BGP-induced inflammation and fibrosis were significantly reduced, suggesting a role for ET-1 in BGP-mediated effects.ET-1 produced effects similar to those of BGP, which were also dependent on NFkB. To study the pathophysiological relevance of hyperphosphatemia invivo, a low-P diet was administered to a group of old animals, showing an improvement in fibrosis, inflammation and respiratory function compared to old mice on a standard diet. These results suggest that age-related hyperphosphatemia induces inflammation, fibrosis, and impaired respiratory function in old mice; these effects appear to be mediated by ET-1 and NFkB activation.

Oral supplementation of inositols effectively recovered lithium-induced cardiac dysfunctions in mice

This study investigates the effects of inositol (INO) supplementation on cardiac changes caused by Li in mice. The study involved 4 groups of C57BL6 mice (n=10 each): (i) mice orally administered with Li2CO3 for 8 weeks, then 4 additional weeks without (Li_group) or (ii) with INO supplementation (Li_INOdelayed_group) (total of 12 weeks); (iii) mice given Li2CO3 and INO supplementation concurrently for 12 weeks (Li+INO_group); (iv) one group left untreated (C–group). The INO was administered as a mixture of myo-inositol and d-chiro-inositol (80:1) in drinking water. The mice were characterised for heart morphology, function, electrical activity, arrhythmogenic susceptibility, and multiorgan histopathology (heart, liver and kidney). Cardiomyocyte size, protein expression of key signalling pathways related to hypertrophy, and transcription levels of ion channel subunits and hypertrophy markers were evaluated in the ventricle tissue. The study found that INO supplementation reduced the Li-induced cardiac adverse effects, including systolic impairment and increased susceptibility to arrhythmias. The positive effect on arrhythmias might be attributed to the restored expression levels of the potassium channel subunit Kv 1.5. Additionally, INO improved cardiomyocyte hypertrophy, possibly by inhibiting the Li-induced activation of the ERK1/2 signalling pathway and by restoring the normal expression level of BNP, and alleviated injury in the liver and kidney. The effect was preventive if INO supplementation was taken concurrently with Li and therapeutic if INO was administered after Li-induced cardiac impairments were established. These results provide new insights into the cardioprotective effect of INO and suggest a potential treatment approach for Li-induced cardiac disease.

Neocortical cholinergic pathology after neonatal brain injury is increased by Alzheimer's disease-related genes in mice

Hypoxic-ischemic encephalopathy (HIE) in neonates causes mortality and neurologic morbidity, including poor cognition with a complex neuropathology. Injury to the cholinergic basal forebrain and its rich innervation of cerebral cortex may also drive cognitive pathology. It is uncertain whether genes associated with adult cognition-related neurodegeneration worsen outcomes after neonatal HIE. We hypothesized that neocortical damage caused by neonatal HI in mice is ushered by persistent cholinergic innervation and interneuron (IN) pathology that correlates with cognitive outcome and is exacerbated by genes linked to Alzheimer's disease. We subjected non-transgenic (nTg) C57Bl6 mice and mice transgenically (Tg) expressing human mutant amyloid precursor protein (APP-Swedish variant) and mutant presenilin (PS1-ΔE9) to the Rice-Vannucci HI model on postnatal day 10 (P10). nTg and Tg mice with sham procedure were controls. Visual discrimination (VD) was tested for cognition. Cortical and hippocampal cholinergic axonal and IN pathology and Aβ plaques, identified by immunohistochemistry for choline acetyltransferase (ChAT) and 6E10 antibody respectively, were counted at P210. Simple ChAT+ axonal swellings were present in all sham and HI groups; Tg mice had more than their nTg counterparts, but HI did not affect the number of axonal swellings in APP/PS1 Tg mice. In contrast, complex ChAT+ neuritic clusters (NC) occurred only in Tg mice; HI increased that burden. The abundance of ChAT+ clusters in specific regions correlated with decreased VD. The frequency of attritional ChAT+ INs in the entorhinal cortex (EC) was increased in Tg shams relative to their nTg counterparts, but HI obviated this difference. Cholinergic IN pathology in EC correlated with NC number. The Aβ deposition in APP/PS1 Tg mice was not exacerbated by HI, nor did it correlate with other metrics. Adult APP/PS1 Tg mice have significant cortical cholinergic axon and EC ChAT+ IN pathologies; some pathology was exacerbated by neonatal HI and correlated with VD. Mechanisms of neonatal HI induced cognitive deficits and cortical neuropathology may be modulated by genetic risk, perhaps accounting for some of the variability in outcomes.

In utero nicotine exposure affects murine palate development.

Despite data linking smoking to increased risk of fetal morbidity and mortality, 11% of pregnant women continue to smoke or use alternative nicotine products. Studies confirm that nicotine exposure during pregnancy increases the incidence of birth defects; however, little research has focused on specific anatomic areas based on timing of exposure. We aim to determine critical in utero and postnatal periods of nicotine exposure that affect craniofacial development, specifically palate growth. Malformation of the palatal structures can result in numerous complications including facial growth disturbance, or impeding airway function. We hypothesized that both in utero and postnatal nicotine exposure will alter palate development. We administered pregnant C57BL6 mice water supplemented with 100 μg/mL nicotine during early pregnancy, throughout pregnancy, during pregnancy and lactation, or lactation only. Postnatal day 15 pups underwent micro-computed tomography (μCT) analyses specific to the palate. Resultant pups revealed significant differences in body weight from lactation-only nicotine exposure, and μCT investigation revealed several dimensions affected by lactation-only nicotine exposure, including palate width, palate and cranial base lengths, and mid-palatal suture width. These results demonstrate the direct effects of nicotine on the developing palate beyond simple tobacco use. Nicotine exposure through tobacco alternatives, cessation methods, and electronic nicotine delivery systems (ENDS) may disrupt normal growth and development of the palate during development and the postnatal periods of breastfeeding. Due to the recent dramatic increase in the use of ENDS, future research will focus specifically on this nicotine delivery method.

Abstract Mo007: Molecular Basis of Sepsis-Induced Cardiomyopathy Under Anthracycline Treatment: Insights from Mouse Model

Anthracyclines constitute a fundamental component in numerous paediatric chemotherapy regimens. However, its myelosuppressive &amp; cardiotoxic nature put patients at risk of sepsis and sepsis-induced cardiomyopathy (SIC). When anthracycline-treated patients develop SIC, successful treatment of sepsis is sufficient for the restoration of cardiac function, giving rise to the 'transient cardiac dysfunction' phenomenon. Although transient it poses compromised clinical outcomes &amp; the mechanism driving this phenomenon remains elusive. We hypothesise that the molecular regulators of the phenomenon lie within cardiac cell populations &amp; is controlled by transcriptional activation. Thus, we aim to model 'transient cardiac dysfunction' in mice and conduct transcriptomics on their heart tissues. ‘Transient cardiac dysfunction’ was modelled in male juvenile C57BL6 mice treated with a cumulative of 10mg/kg doxorubicin followed by sepsis induction via cecal ligation &amp; perforation (CLP) to induce SIC. To recapitulate ‘transient cardiac dysfunction’, antibiotics were administered 20h post-CLP to treat sepsis &amp; restore cardiac function. Controls against doxorubicin (saline treatment) was established. Echocardiography and biological sample curation were conducted at pre-SIC (before CLP), onset-SIC (10h post-CLP) &amp; post-SIC (60h post-CLP). Sepsis was verified based on procalcitonin fold change as compared to pre-SIC (n=3-6). Procalcitonin was 15±1.6 folds higher in dox- (n=3) &amp; 10±0.39 folds higher in saline-treated (n=3) mice at onset-SIC. The infection was more aggressive in dox-treated mice as procalcitonin remained elevated at post-SIC (17.1±2.0, n=4), whereas in saline-treated mice, procalcitonin was reduced by post-SIC (7.9±1.0, n=3). In saline-treated mice, LVEF(%) was reduced at onset-SIC (49.0%±3.0, n=7) from pre-SIC (58.1±1.1, n=7) and recovered to baseline by post-SIC (61.8±1.7, n=5). In the contrary, LVEF in dox-treated mice (n=7) was increased at onset-SIC (62.5±1.7) from pre-SIC (56.0±0.8) &amp; sustained till post-SIC (60.1±1.0), suggesting cardioprotection. Normal distribution was verified before statistical hypothesis testing. In conclusion, ‘transient cardiac dysfunction’ was modelled in saline-treated mice, &amp; novel cardio protective effect was observed in dox-treated mice. Moving forward, longitudinal snRNA-seq will be conducted on whole hearts to identify cardiac cell populations &amp; genes responsible for ‘transient cardiac dysfunction’ &amp; cardioprotection.

Western diet induces mild metabolic impairment and aggravates neuropathology in an experimental mouse model of traumatic brain injury

Traumatic brain injury (TBI) and lifestyle habits such as Western diet (WD) consumption represent two risk factors that affect an individual's health outcome globally. Individuals with TBI have a greater risk of mortality from associated chronic diseases than the general population. WD has been shown to impair cognitive function, decrease the brain's capacity to compensate for insult by affecting recovery as well as induce metabolic syndrome (MetS) which may be a risk factor for poor TBI prognosis. Hence, this study aims to investigate the impact of WD on TBI behavioral outcomes and neuropathology. Eight-week-old male C57BL6 mice were fed either WD or normal chow for 4 weeks prior to TBI induction. At week four, mice underwent either an experimental open-head TBI or a sham procedure. Mice continued their respective diets for four weeks after brain injury. Metabolic, cognitive function, and molecular assessment were performed four weeks after TBI. Results showed that while WD significantly increased fat percentage and elevated plasma cholesterol, there was no change in blood glucose level or body weight, indicating an early stage of MetS. Nevertheless, this was associated with neuroinflammation and impaired cognitive functions. However, there was no significant impact on cardiovascular function and mitochondrial bioenergetics. Importantly, the mild MetS induced by WD triggered basal motor, cognitive deterioration and exacerbated the long-term neuropathology of TBI. Taken together, our work highlights the magnitude of the contribution of lifestyle factors including the type of diet, even in the absence of overt metabolic consequences, on the neurobehavioral prognosis following TBI.

Cutibacterium acnes invades submicron osteocyte lacuno-canalicular networks following implant-associated osteomyelitis.

Cutibacterium acnes, part of normal skin flora, is increasingly recognized as an opportunistic pathogen capable of causing chronic prosthetic joint infections (PJI) associated with total hip and knee arthroplasty. However, there is a paucity of literature examining the pathogenesis of C. acnes during PJI. To study this, we developed an implant-associated osteomyelitis murine model in which 8-10-week-old C57BL6 mice were subjected to transtibial implantation of titanium or stainless-steel L-shaped pins contaminated with C. acnes. Postsurgery, mice were killed on Days 14 and 28 for terminal assessments of (1) bacterial load in bone, implant, and internal organs (heart, spleen, kidney, and liver), (2) bone osteolysis (micro-CT), (3) abscess formation (histology), and (4) systematic electron microscopy (EM). In vitro scanning EM (SEM) confirmed that C. acnes can form biofilms on stainless-steel and titanium implants. In mice, C. acnes could persist for 28 days in the tibia. Also, we observed C. acnes dissemination to internal organs. C. acnes chronic osteomyelitis revealed markedly reduced bone osteolysis and abscess formation compared to Staphylococcus aureus infections. Importantly, transmission EM (TEM) investigation revealed the presence of C. acnes within canaliculi, demonstrating that C. acnes can invade the osteocyte lacuno-canalicular networks (OLCN) within bone. Our preliminary pilot study, for the first time, revealed that the OLCN in bone can be a reservoir for C. acnes and potentially provides a novel mechanism of why C. acnes chronic implant-associated bone infections are difficult to treat.