The Role of Emotional Contagion in the Distress Exhibited by Grouped Mice Exposed to CO₂

Thermal Response of Laboratory Rats (Rattus norvegicus) during the Application of Six Methods of Euthanasia Assessed by Infrared Thermography

Refinement is one of the principles aiming to promote welfare in research animals. The techniques used during an experimental protocol, including euthanasia selection, must prevent and minimize suffering. Although the current euthanasia methods applied to laboratory rodents are accepted, the controversial findings regarding the potential stress/distress they can cause is a field of research. The objective was to assess the thermal response of Wistar rats during various euthanasia methods using infrared thermography (IRT) to determine the method that prevents or diminishes the stress response and prolonged suffering. Pentobarbital (G1), CO2 (G2), decapitation (G3), isoflurane (G4), ketamine + xylazine (G5), and ketamine + CO2 (G6) were evaluated at five evaluation times with IRT to identify changes in the surface temperature of four anatomical regions: ocular (T°ocu), auricular (T°ear), interscapular (T°dor), and caudal (T°tai). Significant differences (p < 0.05) were found in G2 and G4, registering temperature increases from the administration of the drug to the cessation of respiratory rate and heart rate. Particularly, isoflurane showed a marked thermal response in T°ocu, T°ear, T°dor, and T°tai, suggesting that, in general, inhalant euthanasia methods induce stress in rats and that isoflurane might potentially cause distress, an effect that must be considered when deciding humane euthanasia methods in laboratory rodents.

Ability to share emotions of others as a foundation of social learning

The natural habitats of most species are far from static, forcing animals to adapt to continuously changing conditions. Perhaps the most efficient strategy addressing this challenge consists of obtaining and acting upon pertinent information from others through social learning. We discuss how animals transfer information via social channels and what are the benefits of such exchanges, playing out on different levels, from theperception of socially delivered information to emotional sharing, manifesting themselves across different taxa of increasing biological complexity. We also discuss how social learning is influenced by different factors including pertinence of information for survival, the complexity of the environment, sex, genetic relatedness, and most notably, the relationship between interacting partners. The results appear to form a consistent picture once we shift our focus from emotional contagion as a prerequisite for empathy onto the role of shared emotions in providing vital information about the environment. From this point of view, we can propose approaches that are the most promising for further investigation of complex social phenomena, including learning from others.

Voluntary Oral Ingestion of a Sedative Prior to Euthanasia with CO2: Behavioural Responses of Mice

Laboratory mice are commonly euthanised with carbon dioxide (CO₂); however, there is ample evidence that this gas is aversive. Previous work suggests that sedation achieved via injection with benzodiazepines prior to CO₂ administration could reduce aversive behaviours during euthanasia. We explored the potential of using a voluntarily ingested sedative (tiletamine-zolazepam, Zoletil^®) prior to euthanasia. Male and female C57BL/6 mice were allocated into one of the five experimental groups, which differed in the dose of Zoletil: 0, 10, 20, 40, 80 or 100 mg/kg. A dose of 20 mg/kg was found to achieve mild sedation prior to euthanasia; mice which received this dose numerically reared and walked on the cage lid less, and showed ataxia, immobility and recumbency for longer than mice that received a lower dose. During euthanasia, mice that received 20 mg/kg showed fewer aversive responses to CO₂. Doses of 40 to 100 mg/kg were associated with signs of moderate to severe sedation, but resulted in an incomplete intake of the sedative, which made the interpretation of the aversiveness to CO₂ difficult. Voluntary oral administration of a sedative is an effective, affordable, and easy way to minimize the stress of mice to euthanasia with CO₂.

CircRNA-016901 silencing attenuates irradiation-induced injury in bone mesenchymal stem cells via regulating the miR-1249-5p/HIPK2 axis

Currently, bone marrow transplantation remains the basic treatment for various hematological tumors and irradiation is one of the most important pretreatment methods. However, irradiation pretreatment may result in damage to bone mesenchymal stem cells (BMSCs). The present study aimed to investigate the effect of circular RNA-016901 (circ-016901) on the injury of irradiation-induced BMSCs and the underlying mechanism. The expression levels of circ-016901, microRNA-1249-5p (miR-1249-5p) and homeodomain interacting protein kinase 2 (HIPK2) in irradiation-induced mouse BMSCs at various irradiation doses were detected via reverse transcription-quantitative PCR (RT-qPCR). The effect of circ-016901 on cell proliferation was examined using Cell Counting Kit-8 assays following silencing or overexpression of circ-016901. Cell apoptosis was detected by flow cytometry and caspase-3/7 activity. The expression of autophagy-related markers, including Beclin-1 and LC3-II/I, was detected at the mRNA and protein levels by RT-qPCR and western blotting, respectively. Irradiation treatment upregulated the expression of circ-016901 and HIPK2 and downregulated miR-1249-5p expression. The expression levels of LC3-II/I and Beclin-1 in BMSCs were downregulated in a dose-dependent manner. Silencing of circ-016901 promoted proliferation of irradiation-induced BMSCs and attenuated irradiation-induced apoptosis. Moreover, silencing of circ-016901 elevated the expressions of LC3-II/I and Beclin-1 in irradiation-induced BMSCs. Similar results were obtained with miR-1249-5p overexpression and HIPK2 silencing. These results demonstrated that circ-016901 silencing attenuated injury in irradiation-induced mouse BMSCs by regulating the miR-1249-5p/HIPK2 axis, providing a novel target for future research on the mechanism of radiation resistance in BMSCs.