Tail flick test

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Tail flick test apparatus

The tail flick test is a

analgesics, by observing the reaction to heat. It was first described by D'Amour and Smith in 1941.[1]

Procedure

Most commonly, an intense light beam is focused on the animal's tail and a timer starts. When the animal flicks its tail, the timer stops and the recorded time (latency) is a measure of the

pain threshold.[2] Alternate methods can be used to apply heat, such as immersion in hot water.[3]

Alternately, a

resistance wire with a constant heat flow may be used. For the tail flick test, the wire is attached to the tail of the organism, and the wire applies heat to the tail. The researcher then records the latency to tail flick.[4]

Applications

Researchers testing the effectiveness of drugs on the pain threshold often use the tail flick test to measure the extent to which the drug being tested has reduced the amount of pain felt by the model organism.[5]

Both laboratory mice and rats are a common

analgesics, which are responsible for weakening the response to pain. Under these weakened responses to pain, with effectiveness often peaking about 30 minutes after ingestion, researchers test the effectiveness of the drugs by exposing the tail to constant heat and measuring how long it takes to flick, signaling its response to the pain.[6][7] Naloxone and naltrexone, two opioid antagonists, have been used to study pain sensitivity in relation to exercise in mice.[8]

Experimental tests of the tail flick testing method showed that the temperature of the skin of the tail plays a major role in the critical temperature, i.e., the temperature at which the tail flicks in response to pain. Researchers found that if the tail has been exposed to a cooler temperatures before the test, then the critical temperature decreases.[9]

Through use of the tail flick test, researchers have found that genetics play a role in pain sensation and the effectiveness of analgesics. A mouse of one genetic line may be more or less tolerant of pain than a mouse of another genetic line. Also, a mouse of one genetic line may experience a higher or lower effectiveness of an analgesic than a mouse of another genetic line. Using this test, researchers can also begin to identify genes that play a role in pain sensation. For example, the Calca gene (see WikiGenes CALCA) is primarily responsible for the variability in thermal (heat)

modality or motor function in the mice. The mice with the Sprawling mutation were unable to sense the pain, but their other sensory functions were unaffected.[11]

Limitations

The tail flick test is one test to measure heat-induced pain in animals. This reflexive response is an indicator of pain sensitivity in an organism and reduction of pain sensitivity produced by analgesics. Limitations of this test include: the need for more research with

murine subjects, and determining the validity of applying observed pain responses from animals to humans.[12] Also, researchers have found that skin temperature can significantly affect the results of the tail flick test and it is important to consider this effect when performing the test.[13] Lastly, many thermal tests do not distinguish between opioid agonists and mixed agonist-antagonists, and consequently a tail flick test for mice using cold water in place of heat has been developed to allow that distinction.[14]

References

  1. ^ D'Amour, FE; Smith, DL (1941). "A method for determining loss of pain sensation". J Pharmacol Exp Ther. 72 (1): 74โ€“78.
  2. S2CID 942191
    .
  3. ^ Mouse Tail-Flick, Allegheny College – via youtube.com.
  4. PMID 14428053
    .
  5. ^ US Patent 3303199, Doebel, K & Gagneux, A., "Certain Imidazolone Derivatives and Process for Making Same", published 1967-02-07 
  6. PMID 14814606
    .
  7. S2CID 36318349
    .
  8. S2CID 10496331
    .
  9. PMID 14329334
    .
  10. ^ Mogil, Jeffrey S. (2007). "The Surprising Complexity of Pain Testing in the Laboratory Mouse". In Crawley, J (ed.). What's Wrong with My Mouse? Strategies for Rodent Behavior Phenotyping (PDF). San Diego, CA: Society for Neuroscience. pp. 11โ€“23.
  11. PMID 18160659
    .
  12. PMID 11734620
    .
  13. S2CID 43231682
    .
  14. PMID 2867920
    .

External links
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