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Tail handling reduces the value of reward in laboratory mice

Published on: 8 February 2018

Researchers have found that laboratory mice moved by tail handling rather than by tunnel are less responsive to reward which has implications for designing and interpreting scientific studies.

The research published in Scientific Reports describes how tail handling makes laboratory mice less responsive to reward, indicating a more depressive-like state compared to mice handled using a tunnel. This finding adds to the increasing number of studies that show tail handling is an aversive procedure.

The reduction or inability to experience pleasure from rewarding stimuli is known as anhedonia and is a core symptom of clinical depression in humans. In animals, anhedonia is also considered an indicator of a depressive state. It can be measured by assessing how mice consume a sucrose solution as a reward: depressed mice consume less sucrose and the size of their licking bouts when drinking also tend to be smaller.

PhD student Jasmine Clarkson under supervision of Professor Candy Rowe within the Centre for Behaviour and Evolution and colleagues found that tail handled mice showed more anhedonic responses in both measures - drinking less sucrose solution and in shorter licking bouts - than tunnel handled mice. These findings provide the first evidence that handling method affects how laboratory mice perceive and respond to positive rewarding stimuli. The work has significant implications for the welfare of laboratory mice as well as for the design and interpretation of scientific studies, particularly those investigating or involving reward.

Mouse in handling tunnel

Refining handling methods

Work from Professor Jane Hurst’s laboratory at the University of Liverpool has previously identified that the standard practice of picking up laboratory mice by their tails increases behaviours indicative of anxiety and reduces engagement in cognitive tests; issues which can be overcome by picking up mice using a tunnel or cupped hands instead2,3,4.

In the current study, the Newcastle team confirmed the previous tunnel handling work, replicating Professor Hurst’s results in their laboratory. They demonstrated that mice handled by their tails interacted less with the handler and showed greater levels of anxiety in behavioural tests compared to tunnel handled mice. They were also able to demonstrate the beneficial effects of tunnel handling over a longer period of time.

Newcastle is trialling the tunnel handling system with the intention of rolling it out across the University.

The NC3Rs has produced a range of resources to support laboratories in implementing the refined handling methods.

The study has been funded by the BBSRC and is published in Scientific Reports 

(Adapted with thanks from the NC3Rs)


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