Laboratory Animals最新文献

For over 40 years, ivermectin has served as an effective anti-parasitic drug used in human and veterinary medicine. In laboratory animal facilities it is used prophylactically or therapeutically to maintain the health status of the colony or experimentally in studies. Although ivermectin is generally safe to use, there are reports of neurotoxicity associated with ivermectin crossing the blood-brain barrier due to overdosing or blood-brain barrier dysfunction. In mice, P-glycoprotein maintains the blood-brain barrier and mice with a mutation in the P-glycoprotein encoding gene mdr1a are 50-100 times more sensitive to ivermectin. Signs of neurotoxicity include ataxia, bradypnea, recumbency, tremor, and death. We report neurotoxicity after ivermectin administration was used for the purpose of eradicating the murine-specific intestinal nematode Heligmosomoides polygyrus in C57BL/6NTac and C57BL/6NCrl mice. The mice were dewormed by subcutaneous administration of 10 or 20 mg/kg ivermectin to eradicate all stages of Heligmosomoides polygyrus. At 24-48h after deworming, 5% (n = 4) of the mice presented with tremor, ataxia, and/or head tilt. The affected mice were euthanised and gross pathological findings were found in one of the four mice (left-sided hydronephrosis). We assume that the observed neurological effects were due to defects in the blood-brain barrier, overdosing or individual sensitivity. This report provides a reason for caution when deworming laboratory mice subcutaneously with ivermectin at doses of 10 mg/kg or higher.

Blood sampling is often performed during animal studies. This is more challenging in mice than in larger animal species owing to their size and lack of blood vessel visibility. Guidelines for blood sampling in mice and papers on animal welfare often refer to the submandibular, cheek, buccal, and anterior facial veins. However, these terms are imprecise. There are at least two different superficial veins that can be used for blood sampling on the head of the mouse; moreover, most studies ignore this distinction. Inaccurate descriptions and even incorrect labelling of the images lead to confusion and unnecessary delays in learning blood collection techniques, as well as stress and pain in animals due to failed attempts. This review explains the most common terminological errors, demonstrates the distinction between bleeding facial and superficial temporal veins using original photographs, and discusses the suitability of sampling from both veins.

Obtaining sufficient blood volume from mice significantly facilitates experimental research. This study explored the inferior vena cava puncture under continuous cardiac perfusion (IVCP-UCCP) technique and evaluated its efficiency in comparison with conventional cardiac puncture (CP). In an initial dose-finding study, 50 mice were randomly assigned to one of 10 groups with escalating perfusion volume from 0.5 to 4.5 ml in 0.5-ml increments. The minimum perfusion volume was determined to be 2 ml in collecting whole circulating blood. In the next comparison using the conventional method, 40 mice were randomly assigned to one of two groups denoting different blood collection methods: Group 1: CP, Group 2: IVCP-UCCP. The results showed 1) that the cells and undiluted blood volume collected via IVCP-UCCP was over twofold higher than that by CP (p < 0.001), confirmed by the cell counts and hematoxylin-eosin staining of different tissues slides (p < 0.001); 2) the new technique did not alter the cellular composition or viability, which was verified by routine blood tests and flow cytometry (p > 0.05); 3) the blood collected via the novel technique was diluted 2.1 times: the hemato-biochemical indicator results multiplied by 2.1 were identical with the test results of blood from CP (p > 0.05). Together, the refined blood collection method of IVCP-UCCP completely extracted the limited blood resources in mice, significantly enhanced the utilization of each mouse, and thus offered scientific and ethical benefits. This technique may be also applicable for other small animal models.

Pre-immunization with inactivated antigens has been developed as an alternative to the use of 'dirty' mice, which in contrast to specific pathogen free (SPF) mice, harbour a range of pathogens. Within certain research areas, such mice are considered better models for humans than SPF mice, as they have an immune system that better mirrors human immunity. We inactivated murine adenovirus type 1 (FL), minute virus of mice, mouse hepatitis virus (A59), respirovirus muris (Sendai), Theiler's encephalomyelitis virus (GD7) and Mycoplasma pulmonis by ultraviolet irradiation. We show that pre-immunization with these inactivated pathogens combined with adjuvant prior to the dietary induction of obesity in C57BL/6NTac mice substantially reduced the group sizes needed for showing an effect of the GLP-1 receptor analogue, liraglutide. Nesting, open field and novel object behaviours of the mice were unaffected. We conclude that pre-immunization with inactivated pathogens may be a simple tool to increase power in this type of intervention study on the DIO mouse model.

Isoflurane anesthesia prior to carbon dioxide euthanasia is recognized as a refinement by many guidelines. Facilities lacking access to a vaporizer can use the "drop" method, whereby liquid anesthetic is introduced into an induction chamber. Knowing the least aversive concentration of isoflurane is critical. Previous work has demonstrated that isoflurane administered with the drop method at a concentration of 5% is aversive to mice. Other work has shown that lower concentrations (1.7% to 3.7%) of isoflurane can be used to anesthetize mice with the drop method, but aversion to these concentrations has not been tested. We assessed aversion to these lower isoflurane concentrations administered with the drop method, using a conditioned place aversion (CPA) paradigm. Female C57BL/6J (OT-1) mice (n = 28) were randomly allocated to one of three isoflurane concentrations: 1.7%, 2.7%, and 3.7%. Mice were acclimated to a light-dark apparatus. Prior to and following dark (+ isoflurane) and light chamber conditioning sessions, mice underwent an initial and final preference assessment; the change in the duration spent within the dark chamber between the initial and final preference tests was used to calculate a CPA score. Aversion increased with increasing isoflurane concentration: from 1.7% to 2.7% to 3.7% isoflurane, mean ± SE CPA score decreased from 19.6 ± 20.1 s to -25.6 ± 23.2 s, to -116.9 ± 30.6 s (F_1,54 = 15.4, p < 0.001). Our results suggest that, when using the drop method to administer isoflurane, concentrations between 1.7% and 2.7% can be used to minimize female mouse aversion to induction.

When pain might occur during an animal experiment, sufficient analgesia is necessary. Metamizole is the third most used postoperative pain medication in animal research. The analgesic effect of metamizole is supposed to last 6-8 h in rodents. Therefore, the supplementation of drinking water with metamizole should be the preferred method to ensure permanent pain relief without unnecessary stressors. The present exploratory study compared the voluntary intake of metamizole-supplemented drinking water (3 mg/ml) between healthy mice of three different mouse strains. After the addition of metamizole to the drinking water, a marginal reduction in body weight was observed in C57BL/6J and BALB/c mice. However, NSG mice displayed a significantly higher body weight loss and reduction of drinking behavior compared with the C57BL/6J and BALB/c strains. The acceptance of metamizole in NSG mice did not increase with a different metamizole formulation. Thus, the mice of the inbred strains C57BL/6J and BALB/c seemed to be able to adapt to the taste of metamizole, while NSG mice were not able to accustom to analgesia within 1 week. Strain-specific habituation should be considered in future animal studies when analgesia is applied via drinking water.

The knowledge and attitude of researchers can affect the validity of laboratory animal (LAN) research. However, studies show that not all researchers possess the required knowledge and appropriate attitude for performing valid research on animals. This may have several reasons, such as high heterogeneity in the educational backgrounds of researchers in animal trials. In this study, we hypothesized that properly designed intensive educational intervention could improve the knowledge and attitude of a mixed population of researchers, regardless of their heterogeneity. We delivered 10 country-wide two-day LAN workshops for academic members, postgraduate students and members of the ethics committees of the medical universities in Iran. Using pre-/post-intervention design, we found that the intervention highly significantly (p < 0.001) improved the knowledge score (from 2.96 ± 1.483 to 4.63 ± 1.548 mean ± SD; range: 0-8; n = 236) and attitude score (from 62.65 ± 5.160 to 65.57 ± 4.716; range: 14-70; N = 229). We also found that the educational intervention was significantly (p = 0.035) more effective to improve the knowledge of participants with more years of experience in LAN science. Unexpectedly, our younger participants (overall age range: 19-67 years old; mean ± SD: 37.96 ± 9.55) had lower initial attitude score. However, education was significantly (p = 0.002) more effective to improve the attitude score of younger participants. The knowledge and attitude improvements were not related to educational background, gender, history of prior attendance in LAN courses and amount of animal use. Attendees' performance in the final assessment showed that they require more education on the 'anesthesia/analgesia' topic. They also declared a high interest in learning more on the design of LAN studies.