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3 Minute 3Rs podcast: August 2022 transcript

Better behavioural research, imaging with microbots and how housing density affects mouse microbiomes.

Papers behind the pod:

  1. Arjmand S et al. (2022). Tips and traps for behavioural animal experimentation. Acta Neuropsychiatrica, in press. doi: 10.1017/neu.2022.4
  2. Wrede P et al. (2022). Real-time 3D optoacoustic tracking of cell-sized magnetic microrobots circulating in the mouse brain vasculature. Science Advances 8(19). doi: 10.1126/sciadv.abm9132
  3. Russell A et al. (2022). Reduced housing density improves statistical power of murine gut microbiota studies. Cell Reports 39(6): e110783. doi: 10.1016/j.celrep.2022.110783

[NC3Rs]

It’s the third Thursday of August, and you’re listening to 3 Minute 3Rs, your monthly recap of efforts to replace, reduce and refine the use of animals in research. This month we’re starting with some handy tips for anyone interested in conducting high quality behavioural research using animals.

[NA3RsC]

When planning to conduct a behavioral animal experiment there are a lot of things to consider to be sure you are following the 3Rs and generating high quality data. In a new review paper, authors suggest 10 simple tips and traps which are great for students, new graduates, and seasoned researchers who would like a light-hearted refresher.

To start your trip, authors encourage you to have focused hypotheses and confirm that you actually should use animals. Next, you should be personally prepared to have patience, work hard directly with animals, and end the study yourself. Then, use great care in choosing the animal, intervention, and behavioral assays. Pay attention to your animals throughout. Prepare prepare prepare. And consider pilots studies and power. Finally, be sure to keep an open mind to learning new things.

For many more details on this route including helpful tables, figures, and references, read the full paper online.

[NC3Rs]

Next, let’s look at how new technology could reduce animal use and data variability through improved longitudinal studies, where a series of measurements are taken in the same animal at different time points. Real-time, non-invasive imaging is commonly used in this type of study, and a recent paper by Wrede et al. describes a method for imaging using microrobots that can be tracked and manipulated in the bloodstream of ex vivo tissue.

Working with micro-particles in vivo is notoriously difficult, but the imaging technique used by Wrede et al., optoacoustic tomography, overcomes some of the issues associated with other techniques such as MRI, including poor resolution and penetration depth. The team also overcame some of the technique’s limitations, including high levels of background signal from the blood, by incorporating a gold coating and a near-infrared excitation source. This resulted in an imaging system capable of tracking 5 micrometre-sized bots in even the smallest capillaries.

Though not yet ready for use as an in vivo tool, this technology has great potential for reducing the number of animals used in longitudinal preclinical studies. Read the full article in Science Advances to find out more.

And finally, how mice can feel the effect of housing density in their gut – and what that means for designing robust studies.

[LabAnimal]

The community of bacteria and other microorganisms living in the gut, known as the gut microbiome, has an important role in both the maintenance of health and the pathogenesis of disease. Mouse models have been extensively used for microbiome research; however, many factors, including differences in husbandry practices, can affect the results of the studies.

Laboratory mice are typically housed in groups of 4-5 per cage. And as mice eat their droppings, the microbiome of co-housed mice becomes more similar over time, diverging from the microbiome of mice housed in other cages.

In a new study, Russell, Copio and colleagues examined the impact of cage density on the ability to detect the effects of antibiotics on the microbiome. Analysing microbiome composition within and between cages revealed that housing 2 mice per cage increased the ability to detect antibiotic-induced effects on the gut microbiome compared to the higher density of 4 mice per cage. Showing how reducing housing density can increase statistical power of murine gut microbiota studies.

To learn more about this research, read the full paper online.

[NC3Rs]

That’s it for this month’s episode. 3 Minute 3Rs is brought to you each month by Lab Animal, the North American 3Rs Collaborative, and the NC3Rs. If you have another minute spare, please consider rating and reviewing the podcast wherever you listen so we can reach more laboratory animal professionals. Thanks for tuning in, we’ll see you again next month for another 3Rs update.

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