Impact assessment of tail-vein injection in mice using a modified anaesthesia induction chamber versus a common restrainer without anaesthesia

Head-mounted central venous access during optical recordings and manipulations of neural activity in mice

Establishing reliable intravenous catheterization in mice with optical implants allows the combination of neural manipulations and recordings with rapid, time-locked delivery of pharmacological agents. Here we present a procedure for handmade jugular vein catheters designed for head-mounted intravenous access and provide surgical and postoperative guidance for improved survival and patency. A head-mounted vascular access point eliminates the need for a back-mounted button in animals already receiving neural implants, thereby reducing sites of implantation. This protocol, which is readily adoptable by experimenters with previous training and experience in mouse surgery, enables repeated fiber photometry recordings or optogenetic manipulation during drug delivery in adult mice that are awake and behaving, whether head fixed or freely moving. With practice, an experienced surgeon requires ~30 min to perform catheterization on each mouse. Altogether, these techniques facilitate the reliable and repeated delivery of pharmacological agents in mouse models while simultaneously recording at high temporal resolution and/or manipulating neural populations.

Preclinical Mouse Metastatic Model Established Through Induced Lung Metastases

Metastatic disease is the major cause of cancer death, and the lung is one of the most common sites of cancer metastases. To investigate systemic antitumor effects or protective potential of local therapies, mouse models with induced metastases are indispensable in preclinical cancer research. Here, we describe the protocol for the metastatic mouse model established through induced 4T1 mammary carcinoma metastases. With minor prior optimization, it can be applied to other tumor cell lines of interest.

Heterochronic Plasma Transfer: Experimental Design, Considerations, and Technical Challenges

Experimental approaches such as Heterochronic Plasma Transfer (HPT) provide insights into the aging process and help identify the factors that impact aging, with the aim of developing anti-aging therapies. HPT involves the transfer of plasma from an animal of one age to an animal of a different age and highlights the effects of the systemic environment on aging. Despite its importance as an aging research tool, HPT is not without limitations and HPT experiments across various studies differ in key experimental designs considerations, presenting a challenge in obtaining comparable outcomes. In this review, we examine the caveats and experimental design considerations of HPT as a research tool. We provide insights into plasma preparation procedures, route of administration, dosing regimen, and appropriate controls to assist investigators in achieving their experimental goals.

Acclimation and Blood Sampling: Effects on Stress Markers in C57Bl/6J Mice

Blood sampling in rodents is common practice in scientific studies. Some of the refined methods widely used are the puncture of the saphenous vein or tail vein, or even tail docking. The handling needs of these different blood sampling methods are different and can directly affect stress, increasing the variability of the study. Moreover, there is less aversion and stress if the animal is accustomed to the environment, handling and technique. Therefore, our study aimed to assess the influence of these three blood sampling techniques (saphenous puncture, tail vein puncture and tail vein docking) and the use of previous acclimation on different indicators of animal stress, assessing blood glucose concentrations and faecal corticosterone metabolites (FCMs). Twenty-four young adult male and female C57Bl6/J mice were divided in three groups by sampling method: tail docking (TD), saphenous vein puncture (SV) and caudal vein puncture (CV) groups. All mice were studied with and without acclimation, which was performed during 9 consecutive days. The results showed that both males and females present very similar responses to the different handling and sampling methods without significant differences. Nevertheless, acclimation in all sampling methods decreased glucose and FCM levels significantly. The method that obtained the lowest glucose and FCM levels with significance was saphenous vein puncture. Therefore, we can say that it causes less stress when performing prior acclimation, even when this involves greater handling of the animal. Our results contribute to refinement within the 3R concept and could serve researchers to programme and select a good handling technique and a welfare-friendly blood sampling method for their experiments.

Overexpression and ELISA-based detection of asprosin in cultured cells and mice

The unreliability of commercial recombinant asprosin preparations and variability between asprosin detection assays have proven to be a bottleneck in experimental interpretation. This protocol describes the use of viral vectors and expression plasmid for overexpression and secretion of human asprosin to achieve sustained elevation of asprosin protein in mice and HEK293T cells without using recombinant proteins. This protocol also includes a sandwich ELISA using anti-asprosin monoclonal antibodies for detection of asprosin in media from cultured cells and in plasma of mice. For complete details on the use and execution of this protocol, please refer to Duerrschmid et al. (2017), Mishra et al. (2021), and Mishra et al. (2022).

Assembly and operation of an easy-to-make portable device for facilitating mouse lateral tail-vein injection

Drug delivery by lateral tail-vein injection in mice is widely used in preclinical research, but the technique is laborious to perform because the tail vein is hardly visible and too small to be cannulated. Misinjections of test components can lead to defective or even false experiment results. We present a simple but useful injection-assistant device to visualize the tail vein of mice. The device consists of a light-emitting diode (LED) circuit and a finger component. The finger component consists of an open-looped ring to slide on the finger, a slot to accommodate the mouse's tail and a lamp cage in which to set the LED lamp. Once the mouse's tail has been illuminated, the tail vein can be clearly seen as a dark line along the bright background of the tail, which facilitates venipuncture and improves the success rate of tail-vein injection. If the protocol provided has been followed correctly, a robust tail-vein injection-assistant device can be set up in 3 h with low-cost components.

αVβ8 integrin targeting to prevent posterior capsular opacification

Fibrotic posterior capsular opacification (PCO), a major complication of cataract surgery, is driven by transforming growth factor–β (TGF-β). Previously, αV integrins were found to be critical for the onset of TGF-β–mediated PCO in vivo; however, the functional heterodimer was unknown. Here, β8 integrin–conditional knockout (β8ITG-cKO) lens epithelial cells (LCs) attenuated their fibrotic responses, while both β5 and β6 integrin–null LCs underwent fibrotic changes similar to WT at 5 days post cataract surgery (PCS). RNA-Seq revealed that β8ITG-cKO LCs attenuated their upregulation of integrins and their ligands, as well as known targets of TGF-β–induced signaling, at 24 hours PCS. Treatment of β8ITG-cKO eyes with active TGF-β1 at the time of surgery rescued the fibrotic response. Treatment of WT mice with an anti-αVβ8 integrin function blocking antibody at the time of surgery ameliorated both canonical TGF-β signaling and LC fibrotic response PCS, and treatment at 5 days PCS, after surgically induced fibrotic responses were established, largely reversed this fibrotic response. These data suggest that αVβ8 integrin is a major regulator of TGF-β activation by LCs PCS and that therapeutics targeting αVβ8 integrin could be effective for fibrotic PCO prevention and treatment.

A novel multi-parametric analysis of non-invasive methods to assess animal distress during chronic pancreatitis

Ethical responsibility, legal requirements and the need to improve the quality of research create a growing interest in the welfare of laboratory animals. Judging the welfare of animals requires readout parameters, which are valid and sensitive as well as specific to assess distress after different interventions. In the present study, we evaluated the sensitivity and specificity of different non-invasive parameters (body weight change, faecal corticosterone metabolites concentration, burrowing and nesting activity) by receiver operating characteristic curves and judged the merit of a multi-parametric analysis by logistic regression. Chronic pancreatitis as well as laparotomy caused significant changes in all parameters. However, the accuracy of these parameters was different between the two animal models. In both animal models, the multi-parametric analysis relying on all the readout parameters had the highest accuracy when predicting distress. This multi-parametric analysis revealed that C57BL/6 mice during the course of chronic pancreatitis often experienced less distress than mice after laparotomy. Interestingly these data also suggest that distress does not steadily increase during chronic pancreatitis. In conclusion, combining these non-invasive methods for severity assessment represents a reliable approach to evaluate animal distress in models such as chronic pancreatitis.

Administration of Tramadol or Buprenorphine via the drinking water for post-operative analgesia in a mouse-osteotomy model

Adequate analgesia is essential whenever pain might occur in animal experiments. Unfortunately, the selection of suitable analgesics for mice in bone-linked models is limited. Here, we evaluated two analgesics – Tramadol [0.1 mg/ml (T_low) vs. 1 mg/ml (T_high)] and Buprenorphine (Bup; 0.009 mg/ml) – after a pre-surgical injection of Buprenorphine, in a mouse-osteotomy model. The aim of this study was to verify the efficacy of these opioids in alleviating pain-related behaviors, to provide evidence for adequate dosages and to examine potential side effects. High concentrations of Tramadol affected water intake, drinking frequency, food intake and body weight negatively in the first 2–3 days post-osteotomy, while home cage activity was comparable between all groups. General wellbeing parameters were strongly influenced by anesthesia and analgesics. Model-specific pain parameters did not indicate more effective pain relief at high concentrations of Tramadol. In addition, ex vivo high-resolution micro computed tomography (µCT) analysis and histology analyzing bone healing outcomes showed no differences between analgesic groups with respect to newly formed mineralized bone, cartilage and vessels. Our results show that high concentrations of Tramadol do not improve pain relief compared to low dosage Tramadol and Buprenorphine, but rather negatively affect animal wellbeing.

A refinement to the formalin test in mice

The constant refinement of tests used in animal research is crucial for the scientific community. This is particularly true for the field of pain research, where ethical standards are notably sensitive. The formalin test is widely used in pain research and some of its mechanisms resemble those underlying clinical pain in humans. Immediately upon injection, formalin triggers two waves (an early and a late phase) of strong, nociceptive behaviour, characterised by licking, biting, lifting and shaking the injected paw of the animal. Although well characterised at the behaviour level, since its proposal over four decades ago, there has not been any significant refinement to the formalin test, especially those combining minimisation of animal distress and preservation of behavioural outcomes of the test.  Here, we propose a modified and improved method for the formalin test. We show that anaesthetising the animal with the inhalable anaesthetic sevoflurane at the time of the injection can produce reliable, robust and reproducible results whilst animal distress during the initial phase is reduced. Importantly, our results were validated by pharmacological suppression of the behaviour during the late phase of the test with gabapentin, the anaesthetic showing no interference with the drug. In addition, we demonstrate that this is also a useful method to screen for changes in pain behaviour in response to formalin in transgenic lines.

A refinement to the formalin test in mice

The constant refinement of tests used in animal research is crucial for the scientific community. This is particularly true for the field of pain research, where ethical standards are notably sensitive. The formalin test is widely used in pain research and some of its mechanisms resemble those underlying clinical pain in humans. Immediately upon injection, formalin triggers two waves (an early and a late phase) of strong, nociceptive behaviour, characterised by licking, biting, lifting and shaking the injected paw of the animal. Although well characterised at the behaviour level, since its proposal over four decades ago, there has not been any significant refinement to the formalin test, especially those combining minimisation of animal distress and preservation of behavioural outcomes of the test.  Here, we propose a modified and improved method for the formalin test. We show that anaesthetising the animal with the inhalable anaesthetic sevoflurane at the time of the injection can produce reliable, robust and reproducible results whilst animal distress during the initial phase is reduced. Importantly, our results were validated by pharmacological suppression of the behaviour during the late phase of the test with gabapentin, the anaesthetic showing no interference with the drug. In addition, we demonstrate that this is also a useful method to screen for changes in pain behaviour in response to formalin in transgenic lines.