Abstract
The hot plate is a widely used test to assess nociception. The effect of non-nociceptive
factors (weight, sex, activity, habituation, and repeated testing) on hot-plate latency
was examined. Comparison of body weight and hot-plate latency revealed a small but
significant inverse correlation (light rats had longer latencies). Habituating rats
to the test room for 1 hour prior to testing did not decrease hot-plate latency except
for female rats tested on days 2 to 4. Hot-plate latency decreased with repeated daily
testing, but this was not caused by a decrease in locomotor activity or learning to
respond. Activity on the hot plate was consistent across all 4 trials, and prior exposure
to a room-temperature plate caused a similar decrease in latency as rats tested repeatedly
on the hot plate. Despite this decrease in baseline hot-plate latency, there was no
difference in morphine antinociceptive potency. The present study shows that weight,
habituation to the test room, and repeated testing can alter baseline hot-plate latency,
but these effects are small and have relatively little impact on morphine antinociception.
Perspective
This manuscript shows that non-nociceptive factors such as body weight, habituation,
and repeated testing can alter hot-plate latency, but these factors do not alter morphine
potency. In sum, the hot-plate test is an easy to use and reliable method to assess
supraspinally organized nociceptive responses.
Key words
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Article info
Publication history
Published online: August 27, 2010
Accepted:
June 28,
2010
Received in revised form:
June 9,
2010
Received:
March 26,
2010
Footnotes
Supported by NIH grant DA015498 and by funds provided for medical and biological research by the State of Washington Initiative Measure No. 171.
Identification
Copyright
© 2011 American Pain Society. Published by Elsevier Inc. All rights reserved.
