Mouse anesthesia and analgesia

Time course changes in in vivo muscle mechanical function and Ca2+ regulation of force following experimentally induced gradual ovarian failure in mice

The abrupt cessation of ovarian hormone release is associated with declines in muscle contractile function, yet the impact of gradual ovarian failure on muscle contractility across peri-, early- and late-stage menopause remains unclear. In this study, a 4-vinylcyclohexene diepoxide (VCD)-induced ovarian failure mouse model was used to examine time course changes in muscle mechanical function. Plantar flexors of female mice (VCD: n = 10; CON: n = 8) were assessed at 40 (early perimenopause), 80 (late perimenopause), 120 (menopause onset) and 176 (late menopause) days post-initial VCD injection. A torque-frequency relationship was established across a range of frequencies (10-200 Hz). Isotonic dynamic contractions were elicited against relative loads (10-80% maximal isometric torque) to determine the torque-velocity-power relationship. Mice then performed a fatigue task using intermittent 100 Hz isometric contractions until torque dropped by 60%. Recovery of twitch, 10 Hz and 100 Hz torque were tracked for 10 min post-task failure. Additionally, intact muscle fibres from the flexor digitorum brevis underwent a fatigue task (50 repetitions at 70 Hz), and 10 and 100 Hz tetanic [Ca2+] were monitored for 10 min afterward. VCD mice exhibited 16% lower twitch torque than controls across all time points. Apart from twitch torque, 10 Hz torque and 10 Hz tetanic [Ca2+], where VCD showed greater values relative to pre-fatigue during recovery, no significant differences were observed between control and VCD mice during recovery. These results indicate that gradual ovarian failure has minimal detriments to in vivo muscle mechanical function, with minor alterations observed primarily for low-frequency stimulation during recovery from fatigue.

Pyramidal neurons form active, transient, multilayered circuits perturbed by autism-associated mutations at the inception of neocortex

Cortical circuits are composed predominantly of pyramidal-to-pyramidal neuron connections, yet their assembly during embryonic development is not well understood. We show that mouse embryonic Rbp4-Cre cortical neurons, transcriptomically closest to layer 5 pyramidal neurons, display two phases of circuit assembly in vivo. At E14.5, they form a multi-layered circuit motif, composed of only embryonic near-projecting-type neurons. By E17.5, this transitions to a second motif involving all three embryonic types, analogous to the three adult layer 5 types. In vivo patch clamp recordings and two-photon calcium imaging of embryonic Rbp4-Cre neurons reveal active somas and neurites, tetrodotoxin-sensitive voltage-gated conductances, and functional glutamatergic synapses, from E14.5 onwards. Embryonic Rbp4-Cre neurons strongly express autism-associated genes and perturbing these genes interferes with the switch between the two motifs. Hence, pyramidal neurons form active, transient, multi-layered pyramidal-to-pyramidal circuits at the inception of neocortex, and studying these circuits could yield insights into the etiology of autism.

Effects of Calcium Carbonate Microcapsules and Nanohydroxyapatite on Properties of Thermosensitive Chitosan/Collagen Hydrogels

Thermosensitive chitosan/collagen hydrogels are osteoconductive and injectable materials. In this study, we aimed to improve these properties by adjusting the ratio of nanohydroxyapatite particles to calcium carbonate microcapsules in a β-glycerophosphate-crosslinked chitosan/collagen hydrogel. Two hydrogel systems with 2% and 5% nanohydroxyapatite particles were studied, each of which had varying microcapsule content (i.e., 0%, 1%, 2%, and 5%). Quercetin-incorporated calcium carbonate microcapsules were prepared. Calcium carbonate microcapsules and nanohydroxyapatite particles were then added to the hydrogel according to the composition of the studied system. The properties of the hydrogels, including cytotoxicity and biocompatibility, were investigated in mice. The calcium carbonate microcapsules were 2-6 µm in size, spherical, with rough and nanoporous surfaces, and thus exhibited a burst release of impregnated quercetin. The 5% nanohydroxyapatite system is a solid particulate gel that supports homogeneous distribution of microcapsules in the three-dimensional matrix of the hydrogels. Calcium carbonate microcapsules increased the mechanical and physical strength, viscoelasticity, and physical stability of the nanohydroxyapatite hydrogels while decreasing their porosity, swelling, and degradation rates. The calcium carbonate microcapsules-nanohydroxyapatite hydrogels were noncytotoxic and biocompatible. The properties of the hydrogel can be tailored by adjusting the ratio of calcium carbonate microcapsules to the nanohydroxyapatite particles. The 1% calcium carbonate microcapsules containing 5% nanohydroxyapatite particle-chitosan/collagen hydrogel exhibited mechanical and physical strength, permeability, and prolonged release profiles of quercetin, which were superior to those of the other studied systems and were optimal for promoting bone regeneration and delivering natural flavonoids.

BPTF activates the MAPK pathway through coexpression with Raf1 to promote proliferation of T‑cell lymphoma

The aim of the present study was to explore the role and biological function of bromodomain PHD finger transcription factor (BPTF) in T-cell lymphoma. Reverse transcription-quantitative PCR (RT-qPCR), western blotting, immunohistochemistry and bioinformatics analysis were used to determine the expression levels of BPTF and Raf1 in T-cell lymphoma tissues and matched adjacent normal tissues. RT-qPCR and western blot analyses were used to examine the role of BPTF in the activation of MAPK signaling. The function of BPTF and Raf1 in T-cell lymphoma was investigated through in vitro and in vivo assays (MTT assay, colony formation assay, flow cytometry, western blotting, tumor xenograft model and TUNEL assay) following silencing and overexpression experiments in Hut-102 cells. The results demonstrated that BPTF and Raf1 were overexpressed in T-cell lymphoma tissues compared with normal tissues, and high expression of BPTF or Raf1 was associated with advanced clinical stage. BPTF promoted the activation of the MAPK pathway and was coexpressed with Raf1 in T-cell lymphoma tissues. Functional assays demonstrated that silencing of BPTF or Raf1 in Hut-102 cells suppressed cell proliferation and induced apoptosis. Furthermore, the carcinogenic effect of BPTF was confirmed by xenograft experiments in nude mice. The present findings suggested that BPTF may function as a crucial oncogenic factor and may serve as a novel therapeutic target in T-cell lymphoma.

General anesthesia globally synchronizes activity selectively in layer 5 cortical pyramidal neurons

General anesthetics induce loss of consciousness, a global change in behavior. However, a corresponding global change in activity in the context of defined cortical cell types has not been identified. Here, we show that spontaneous activity of mouse layer 5 pyramidal neurons, but of no other cortical cell type, becomes consistently synchronized in vivo by different general anesthetics. This heightened neuronal synchrony is aperiodic, present across large distances, and absent in cortical neurons presynaptic to layer 5 pyramidal neurons. During the transition to and from anesthesia, changes in synchrony in layer 5 coincide with the loss and recovery of consciousness. Activity within both apical and basal dendrites is synchronous, but only basal dendrites’ activity is temporally locked to somatic activity. Given that layer 5 is a major cortical output, our results suggest that brain-wide synchrony in layer 5 pyramidal neurons may contribute to the loss of consciousness during general anesthesia.

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Activity of layer 5 PNs synchronizes globally in different anesthetics

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Other mouse cortical cell types show no consistent increase in synchrony

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Changes in layer 5 synchrony coincide with the loss and recovery of consciousness

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Basal, but not apical, layer 5 dendrites are in synchrony with somas

Cholinergic modulation of sensory processing in awake mouse cortex

Cholinergic modulation of brain activity is fundamental for awareness and conscious sensorimotor behaviours, but deciphering the timing and significance of acetylcholine actions for these behaviours is challenging. The widespread nature of cholinergic projections to the cortex means that new insights require access to specific neuronal populations, and on a time-scale that matches behaviourally relevant cholinergic actions. Here, we use fast, voltage imaging of L2/3 cortical pyramidal neurons exclusively expressing the genetically-encoded voltage indicator Butterfly 1.2, in awake, head-fixed mice, receiving sensory stimulation, whilst manipulating the cholinergic system. Altering muscarinic acetylcholine function re-shaped sensory-evoked fast depolarisation and subsequent slow hyperpolarisation of L2/3 pyramidal neurons. A consequence of this re-shaping was disrupted adaptation of the sensory-evoked responses, suggesting a critical role for acetylcholine during sensory discrimination behaviour. Our findings provide new insights into how the cortex processes sensory information and how loss of acetylcholine, for example in Alzheimer's Disease, disrupts sensory behaviours.

Mouse Anesthesia: The Art and Science

There is an art and science to performing mouse anesthesia, which is a significant component to animal research. Frequently, anesthesia is one vital step of many over the course of a research project spanning weeks, months, or beyond. It is critical to perform anesthesia according to the approved research protocol using appropriately handled and administered pharmaceutical-grade compounds whenever possible. Sufficient documentation of the anesthetic event and procedure should also be performed to meet the legal, ethical, and research reproducibility obligations. However, this regulatory and documentation process may lead to the use of a few possibly oversimplified anesthetic protocols used for mouse procedures and anesthesia. Although a frequently used anesthetic protocol may work perfectly for each mouse anesthetized, sometimes unexpected complications will arise, and quick adjustments to the anesthetic depth and support provided will be required. As an old saying goes, anesthesia is 99% boredom and 1% sheer terror. The purpose of this review article is to discuss the science of mouse anesthesia together with the art of applying these anesthetic techniques to provide readers with the knowledge needed for successful anesthetic procedures. The authors include experiences in mouse inhalant and injectable anesthesia, peri-anesthetic monitoring, specific procedures, and treating common complications. This article utilizes key points for easy access of important messages and authors’ recommendation based on the authors’ clinical experiences.

In Vivo Phage Display as a Biomarker Discovery Tool for the Complex Neural Injury Microenvironment

The heterogeneous injury pathophysiology of traumatic brain injury (TBI) is a barrier to developing highly sensitive and specific diagnostic tools. Phage display, a protein-protein screening technique routinely used in drug development, has the potential to be a powerful biomarker discovery tool for TBI. However, analysis of these large and diverse phage libraries is a bottleneck to moving through the discovery pipeline in a timely and efficient manner. This article describes a unique discovery pipeline involving domain antibody (dAb) phage in vivo biopanning and next-generation sequencing (NGS) analysis to identify targeting motifs that recognize distinct aspects of TBI pathology. To demonstrate this process, we conduct in vivo biopanning on the controlled cortical impact mouse model of experimental TBI at 1 and 7 days postinjury. Phage accumulation in target tissues is quantified via titers before NGS preparation and analysis. This phage display biomarker discovery pipeline for TBI successfully achieves discovery of temporally specific TBI targeting motifs and may further TBI biomarker research for other characteristics of injury. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Phage production and purification Support Protocol: Controlled cortical impact model Basic Protocol 2: Injection and elution of phage Basic Protocol 3: Amplicon sequencing and sequence analysis.

Evaluation of Lidocaine and Metabolite Pharmacokinetics in Hyaluronic Acid Injection

Lidocaine-incorporated hyaluronic acid injection (LHA) is considered a promising way to increase patient compliance. Various reviews and analyses have been conducted to verify that the addition of lidocaine had no effect on the product quality of hyaluronic acid injections. However, possible pharmacokinetic (PK) alterations of lidocaine and its active metabolites, monoethylglycylxylidide (MEGX) and glycylxylidide (GX), in hyaluronic acid injection have not been studied so far. Thus, the objective of this study was to evaluate lidocaine and its metabolite PK after 0.3% lidocaine solution or LHA injection and to investigate any changes in PK profiles of lidocaine and its active metabolites. To do this, a novel bio-analytical method for simultaneous determination of lidocaine, MEGX, and GX in rat plasma was developed and validated. Then, plasma concentrations of lidocaine and its active metabolites MEGX and GX following subcutaneous (SC) injection of 0.3% lidocaine solution or LHA with 0.3–1% lidocaine in male Sprague-Dawley rats were successfully determined. The obtained data were used to develop a parent-metabolite pharmacokinetic (PK) model for LHA injection. The half-life, dose-normalized C_max, and AUC_inf of lidocaine after SC injection of lidocaine solution and LHA did not show statistically significant difference. The PK characteristics of lidocaine after LHA administration were best captured using a two-compartment model with combined first-order and transit absorption and its clearance described with Michaelis–Menten and first-order elimination kinetics. Two one-compartment models were consecutively added to the parent model for the metabolites. In conclusion, the incorporation of lidocaine in hyaluronic acid filler injection did not alter the chemical’s pharmacokinetic characteristics.

Amitriptyline Reduces Sepsis-Induced Brain Damage Through TrkA Signaling Pathway

Sepsis can induce acute and chronic changes in the central nervous system termed sepsis-associated encephalopathy (SAE). Not only cognitive deficits but also anxiety, depression, and post-traumatic stress disorder are common in severe sepsis survivors. In this study, we demonstrated that amitriptyline, a classic tricyclic antidepressant, reduced sepsis-induced brain damage through the tropomyosin receptor kinase A (TrkA) signaling pathway. Amitriptyline ameliorated neuronal loss assessed by Nissl staining in a mouse cecal ligation and puncture (CLP)-induced sepsis model. Furthermore, amitriptyline reduced early gliosis assessed by immunofluorescence and late cognitive deficits assessed by the Morris water maze (MWM) test. Moreover, amitriptyline treatment attenuated oxidative stress indicated by less superoxide dismutase (SOD) and catalase (CAT) activity consumption and malondialdehyde (MDA) accumulation. Interestingly, those protective effects of amitriptyline could be abolished by GW441756, a TrkA signaling pathway inhibitor. Immunoblot directly showed that TrkA signaling pathway-associated proteins, such as Akt and GSK3β, were involved in the neuroprotective effects of amitriptyline. Thus, amitriptyline appears to be an encouraging candidate to treat cognitive deficits and depression after severe sepsis.

A Functional Assay to Assess Toxicity During Murine B Cell Development In Vitro

B lymphocytes, or B cells, are important players in immunity that produce antigen-specific immunoglobulins. As a result, they are involved in various immune-linked pathologies. To better understand, prevent, or treat B cell-associated disease and immunotoxicity, we developed an in vitro assay to model early murine B cell differentiation within the bone marrow. This model uses sorted B cell precursors cultured on a supporting stromal cell layer, which over time acquire markers of further differentiated B cells, such as surface antigens and rearranged immunoglobulin light chain. Importantly, we utilized our in vitro model to validate our previous observations that xenobiotics, such as tungsten and organotins, alter B cell development in vivo. Furthermore, gene expression can be modulated in this model using retroviral transduction, making it amenable to investigating signaling pathways involved in disruption of B cell differentiation. © 2019 by John Wiley & Sons, Inc. Basic Protocol: Assessment of early B lymphocyte differentiation in vitro Support Protocol: Isolation of murine bone marrow Alternate Protocol 1: Addition of recombinant interleukin-7 Alternate Protocol 2: Genetic manipulation via retroviral transduction.

Experimental Mouse Model of Bleomycin-Induced Skin Fibrosis

Systemic sclerosis (SSc) refers to an autoimmune disease, which is manifested by inflammation, vasculopathy, and fibrosis of the skin and internal organs. There are a number of different animal models recapitulating specific aspects of SSc. The experimental mouse model of bleomycin-induced skin fibrosis is commonly used to study the pathogenesis observed in SSc. In this model, repetitive intradermal injections of the cytotoxic agent bleomycin trigger progressive skin thickening, associated with excessive accumulation of collagen, infiltration of immune cells, and formation of α-smooth muscle actin (α-SMA)-positive myofibroblasts. In this article, we provide a detailed protocol for the induction of skin fibrosis in experimental mice by bleomycin. Moreover, we describe procedures for processing and analyzing affected skin tissue, provide troubleshooting, highlight advantages and limitations of the presented model, and critically discuss representative results. © 2019 by John Wiley & Sons, Inc. Basic Protocol 1: Intradermal bleomycin injections to induce skin fibrosis in mice Support Protocol: Mouse tissue collection for fibrosis evaluation and for other molecular assays Basic Protocol 2: Evaluation of mouse skin thickness using Masson's trichrome staining Basic Protocol 3: Measurement of hydroxyproline content in skin tissue using a colorimetric assay Basic Protocol 4: Evaluation of myofibroblasts in mouse skin by immunohistochemistry.

Guidelines for measuring cardiac physiology in mice

Cardiovascular disease is a leading cause of death, and translational research is needed to understand better mechanisms whereby the left ventricle responds to injury. Mouse models of heart disease have provided valuable insights into mechanisms that occur during cardiac aging and in response to a variety of pathologies. The assessment of cardiovascular physiological responses to injury or insult is an important and necessary component of this research. With increasing consideration for rigor and reproducibility, the goal of this guidelines review is to provide best-practice information regarding how to measure accurately cardiac physiology in animal models. In this article, we define guidelines for the measurement of cardiac physiology in mice, as the most commonly used animal model in cardiovascular research.

Listen to this article’s corresponding podcast at http://ajpheart.podbean.com/e/guidelines-for-measuring-cardiac-physiology-in-mice/.

MRI in the Study of Animal Models of Neurodegenerative Diseases

Magnetic Resonance Imaging (MRI) is an important tool to study various animal models of degenerative diseases. This chapter describes routine protocols of T ₁-, T ₂-, and T ₂*-weighted and diffusion-weighted MRI for rodent brain and spinal cord. These protocols can be used to measure atrophy, axonal and myelin injury and changes in white matter connectivity.

Microbiota Analysis Using an Illumina MiSeq Platform to Sequence 16S rRNA Genes

The microbiota have been shown to play an important role in diverse biological processes including immunity, metabolism, and digestion. Assessing the exact composition of the microbiota has proven challenging due to the often unknown growth specificities of its members, and culture-based approaches typically fail to capture the complete diversity of microorganisms present. Next Generation Sequencing (NGS) methods provide an efficient means to gather information about cultured and uncultured members of the microbiota. This article provides a method to characterize bacterial communities in terms of species composition using high-throughput sequencing. Briefly, by extracting the entire DNA content of a microbiota sample and performing a targeted high-throughput sequencing of the 16S rRNA gene, a phylogenetic marker for prokaryotes, prediction of the composition of the entire bacterial community is made possible. © 2017 by John Wiley & Sons, Inc.

Exploration of Inflammatory Bowel Disease in Mice: Chemically Induced Murine Models of Inflammatory Bowel Disease (IBD)

Inflammatory bowel disease (IBD) is a chronic multifactorial inflammatory disorder characterized by periods of activation and remission of intestinal inflammation, with potentially severe complications, that can lead to mortality. Experimental animal models of intestinal inflammation are crucial for understanding the pathogenesis of Crohn's disease (CD) and ulcerative colitis (UC), the two major human IBD phenotypes. Animal models have been instrumental in unveiling the molecular background of IBD, and although a single model is not able to capture the complexity of this disease, each of them provided valuable insight into its different aspects. Chemically induced models of intestinal inflammation, mainly dextran sodium sulfate (DSS)- and 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis, are widely used. This article describes DSS- and TNBS-induced colitis models and their relevance to IBD pathophysiology and pre-clinical therapeutic management. © 2017 by John Wiley & Sons, Inc.

A Mouse Model for Ocular Surface Staphylococcus aureus Infection

Creation of an appropriate animal model that accurately reflects the disease and host immune response to bacterial infection in humans is a major challenge in ocular-surface infection research. For decades, mice have been the ideal small animal model for ocular-surface infection research because of the availability and relatively low cost of various genetic backgrounds, targeted defects, and immunologic reagents. By employing different combinations of mouse and bacterial strains, murine infection models can be used to explore a complete picture of bacterial infection and innate immunity of the ocular surface. A murine model of Staphylococcus aureus infection under normal ocular circumstances is presented here as a convenient and tractable model system in which to study mammalian host responses to pathogens. © 2017 by John Wiley & Sons, Inc.

Analysis of mtDNA/nDNA Ratio in Mice

Mitochondrial DNA (mtDNA) lacks the protection provided by the nucleosomes in the nuclear DNA and does not have a DNA repair mechanism, making it highly susceptible to damage, which can lead to mtDNA depletion. mtDNA depletion compromises the efficient function of cells and tissues and thus impacts negatively on health. Here, we describe a brief and easy protocol to quantify mtDNA copy number by determining the mtDNA/nDNA ratio. The procedure has been validated using a cohort of young and aged mice. © 2017 by John Wiley & Sons, Inc.

Continuous IV Infusion is the Choice Treatment Route for Arginine-vasopressin Receptor Blocker Conivaptan in Mice to Study Stroke-evoked Brain Edema

Stroke is one of the major causes of morbidity and mortality in the world. Stroke is complicated by brain edema and other pathophysiological events. Among the most important players in the development and evolution of stroke-evoked brain edema is the hormone arginine-vasopressin and its receptors, V1a and V2. Recently, the V1a and V2 receptor blocker conivaptan has been attracting attention as a potential drug to reduce brain edema after stroke. However, animal models which involve conivaptan applications in stroke research need to be modified based on feasible routes of administration. Here the outcomes of 48 hr continuous intravenous (IV) are compared with intraperitoneal (IP) conivaptan treatments after experimental stroke in mice. We developed a protocol in which middle cerebral artery occlusion was combined with catheter installation into the jugular vein for IV treatment of conivaptan (0.2 mg) or vehicle. Different cohorts of animals were treated with 0.2 mg bolus of conivaptan or vehicle IP daily. Experimental stroke-evoked brain edema was evaluated in mice after continuous IV and IP treatments. Comparison of the results revealed that the continuous IV administration of conivaptan alleviates post-ischemic brain edema in mice, unlike the IP administration of conivaptan. We conclude that our model can be used for future studies of conivaptan applications in the context of stroke and brain edema.

Analysis of Mitochondrial Respiratory Chain Supercomplexes Using Blue Native Polyacrylamide Gel Electrophoresis (BN-PAGE)

Mitochondria are cellular organelles that harvest energy in the form of ATP through a process termed oxidative phosphorylation (OXPHOS), which occurs via the protein complexes of the electron transport chain (ETC). In recent years it has become unequivocally clear that mitochondrial complexes of the ETC are not static entities in the inner mitochondrial membrane. These complexes are dynamic and in mammals they aggregate in different stoichiometric combinations to form supercomplexes (SCs) or respirasomes. It has been proposed that the net respiration is more efficient via SCs than via isolated complexes. However, it still needs to be determined whether the activity of a particular SC is associated with a disease etiology. Here we describe a simplified method to visualize and assess in-gel activity of SCs and the individual complexes with good resolution using blue native polyacrylamide gel electrophoresis (BN-PAGE).

Optimized Heart Sampling and Systematic Evaluation of Cardiac Therapies in Mouse Models of Ischemic Injury: Assessment of Cardiac Remodeling and Semi-Automated Quantification of Myocardial Infarct Size

Cardiac therapies are commonly tested preclinically in small-animal models of myocardial infarction. Following functional evaluation, post-mortem histological analysis is essential to assess morphological and molecular alterations underlying the effectiveness of treatment. However, non-methodical and inadequate sampling of the left ventricle often leads to misinterpretations and variability, making direct study comparisons unreliable. Protocols are provided for representative sampling of the ischemic mouse heart followed by morphometric analysis of the left ventricle. Extending the use of this sampling to other types of in situ analysis is also illustrated through the assessment of neovascularization and cellular engraftment in a cell-based therapy setting. This is of interest to the general cardiovascular research community as it details methods for standardization and simplification of histo-morphometric evaluation of emergent heart therapies. © 2015 by John Wiley & Sons, Inc.

Aging Research Using Mouse Models

Despite the dramatic increase in human lifespan over the past century, there remains pronounced variability in "health-span," or the period of time in which one is generally healthy and free of disease. Much of the variability in health-span and lifespan is thought to be genetic in origin. Understanding the genetic mechanisms of aging and identifying ways to boost longevity is a primary goal in aging research. Here, we describe a pipeline of phenotypic assays for assessing mouse models of aging. This pipeline includes behavior/cognition testing, body composition analysis, and tests of kidney function, hematopoiesis, and immune function, as well as physical parameters. We also describe study design methods for assessing lifespan and health-span, and other important considerations when conducting aging research in the laboratory mouse. The tools and assays provided can assist researchers with understanding the correlative relationships between age-associated phenotypes and, ultimately, the role of specific genes in the aging process.