Research articles

Tomsits and colleagues investigated the effects of medetomidine/midazolam/fentanyl and isoflurane/fentanyl narcosis on murine cardiac autonomic nervous activity and electrophysiology. The results show that, compared with medetomidine/midazolam/fentanyl narcosis, isoflurane/fentanyl narcosis seems to have no effect on cardiac autonomic nervous function and less influence on cardiac electrophysiology.

A large number of refinements have been studied with the aim to improve rat welfare, but more evidence is needed to fully understand their impact. This mapping review draws on the findings of 1,017 studies to show that different refinements impact different rats in different ways, and that a ‘one-size-fits-all’ approach to refinements might not be appropriate.

Using behavioral assays, transcriptome analysis and viral approaches to manipulate gene expression in the mPFC, Zhang et al. identified an important role for early growth response 2 (Egr2/Krox-20) in the development of social and cooperative behaviors in mice.

A clinically relevant murine model of septic arthritis via direct inoculation of methicillin-resistant Staphylococcus aureus into the knee joint is described. This protocol details methods for serum, synovial fluid and knee joint tissue analysis that more closely mimic the workup of septic arthritis in human patients.

Rats undergoing the stress-enhanced fear learning procedure are usually housed in social isolation and exposed to a trauma-like experience of 15 massed electric footshocks. By showing that group-housed rats receiving fewer and lower-magnitude electric shocks still exhibit PTSD-relevant changes, this new study presents refinements of the procedure to reduce potential animal pain.

The authors describe an optimized protocol for rat sperm cryopreservation and in vitro fertilization using frozen–thawed sperm.

Sound levels, vibration, temperature, humidity and luminance were recorded in an animal facility that houses nonhuman primates; the findings may be used to characterize environmental conditions in similar primate facilities and inform best practices for nonhuman primate research and care.

Giannuzzi et al. present an integrated analysis of clinical features and exome and RNA sequencing data in a cohort of dogs with diffuse large B-cell lymphoma to better define the genetic landscape of this tumor and identify multiple mutations associated with the outcome.

In this article, the authors identify LanCL1 as a major male germ cell-specific antioxidant gene. Using different mouse models, they show that LanCL1 deficiency results in spermatozoal oxidative damage and impaired male fertility, while LanCL1 transgene expression protects mice against high-fat-diet-induced oxidative damage and subfertility.

This protocol describes an in vivo cartilage formation assay. Human or bovine articular chondrocytes injected in nude mice form cartilage organoids that can be used for the screening of molecules that promote cartilage formation.

In this article, Henry et al. examine how the geometry, size, opacity and depth of test chambers influence common behavioral responses in Artemia franciscana.

This protocol details the procedures for safe cardiac catheterization in Landrace pigs, basic electrophysiological assessment of conduction properties, induction of atrial fibrillation and development of a myocardial infarction model.

Survey data from 1,187 US biomedical researchers using vertebrate animals reveal diverse perspectives within the animal research community on issues of reproducibility and rigor, attrition rates in drug development, research oversight, and public engagement.

This protocol details the fabrication and application of a 3D-printed device for facilitating lateral tail-vein injection in mice. The tail vein–illuminating ring comprises a light-emitting diode (LED) lamp box on the side; once the tail has been illuminated by the LED, the vein is more clearly visible along the lateral side of the mouse tail.

In this article, the authors characterize a new swine model of invasive pneumococcal pneumonia in mechanically ventilated pigs to mimic clinical conditions of critically ill patients.

Enchytraeus crypticus is a soil-dwelling annelid worm that has been used over the past two decades as an ecotoxicology model. Here, Mónica Amorim and colleagues present the first genome for E. crypticus. The authors identify a number of expanded gene families, including several involved with innate immunity.

In this article, the authors compared 24-h spontaneous locomotor activity in three different mouse strains (two inbred strains and one outbred strain) over a period of 2 months by using an automated recording home-cage device. Analysis of different metrics revealed strain-specific spontaneous locomotor patterns.

Long et al. examined the gut microbiome of C57BL/6 mice from two production sites of three different vendors upon receipt, and as the mice adapted to the new vivarium at the University of Connecticut Health Center. Bacterial proportional abundance varied among mice from each vendor, and mice from all vendors exhibited changes in microbial profiles over time. These findings support the need to consider the microbiome as a potential source of variation in mouse studies.

In this article, the authors evaluate the suitability and effectiveness of their micropipette-guided drug administration method as an alternative and non-invasive administration strategy for clozapine-N-oxide in chemogenetic studies using designer receptors exclusively activated by designer drugs.

A new rat model of brainstem ischemia is described. Selective ligation of four points of the lower basilar artery causes a localized brainstem ischemic lesion in adult rats, resulting in hemiparesis, as well as abnormal posture, body balance and locomotion.