Highlights
- •Bedding material affected evoked baseline behavioral mechanical and heat thresholds.
- •Bedding affected the dynamic range of mechanical thresholds after acute CFA inflammation.
- •Chronic CFA revealed the effects of bedding on mechanical and heat thresholds.
- •Nonreflexive ongoing behaviors were unaffected by bedding materials.
Abstract
It has long been known that the bedding type on which animals are housed can affect
breeding behavior and cage environment, yet little is known about its effects on evoked
behavior responses or nonreflexive behaviors. C57BL/6 mice were housed for 2 weeks
on 1 of 5 bedding types: aspen Sani-Chips (standard bedding for our institute), ALPHA-Dri,
Cellu-Dri, Pure-o’Cel, or TEK-Fresh. Mice housed on aspen exhibited the lowest (most
sensitive) mechanical thresholds and those on TEK-Fresh exhibited 3-fold higher thresholds.
Although bedding type had no effect on responses to punctate or dynamic light touch
stimuli, TEK-Fresh-housed animals exhibited greater responsiveness in a noxious needle
assay than did those housed on the other bedding types. Heat sensitivity was also
affected by bedding because animals housed on aspen exhibited the shortest (most sensitive)
latencies to withdrawal, whereas those housed on TEK-Fresh had the longest (least
sensitive) latencies to response. Slight differences between bedding types were also
seen in a moderate cold temperature preference assay. A modified tactile conditioned
place preference chamber assay revealed that animals preferred TEK-Fresh to aspen
bedding. Bedding type had no effect in a nonreflexive wheel running assay. In both
acute (2 day) and chronic (5 week) inflammation induced by injection of complete Freund's
adjuvant in the hindpaw, mechanical thresholds were reduced in all groups regardless
of bedding type, but TEK-Fresh and Pure-o’Cel groups exhibited a greater dynamic range
between controls and inflamed cohorts than aspen-housed mice.
Perspective
These findings indicate that the bedding type routinely used to house animals can
markedly affect the dynamic range of mechanical and heat behavior assays under normal
and tissue injury conditions. Among beddings tested, TEK-Fresh bedding resulted in
the least sensitive baseline thresholds for mechanical and thermal stimuli and the
greatest dynamic range after tissue injury. Therefore, selection of routine cage bedding
material should be carefully considered for animals that will be tested in behavioral
somatosensory assays.
Key words
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Article info
Publication history
Published online: October 06, 2015
Accepted:
August 31,
2015
Received in revised form:
August 31,
2015
Received:
March 26,
2015
Footnotes
The research reported in this manuscript was supported by NIH grants NS040538 and NS070711 to C.L.S. Partial support for this work was provided by the Research and Education Component of the Advancing a Healthier Wisconsin Endowment at the Medical College of Wisconsin. The authors have no conflicts of interest to report.
Identification
Copyright
© 2016 American Pain Society. Published by Elsevier Inc. All rights reserved.
