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The formalin test: an evaluation of the method.
Arne Tjølsen1, Odd-Geir Berge, Steinar Hunskaar
1Department of Physiology University of Bergen Norway Department of Public Health and Primary Health Care, University of Bergen Norway Astra Pain Control, SödertäljeSweden.
Pain
|October 1, 1992
Summary
The formalin test measures pain by inducing moderate tissue injury in rodents. This test reveals distinct early and late phases of nociception, influenced by factors like inflammation and temperature.
Area of Science:
- Neuroscience
- Pharmacology
- Pain Research
Background:
- Traditional nociception tests use brief stimuli, unlike the formalin test's sustained pain model.
- The formalin test involves moderate, continuous pain from injured tissue, primarily in rats and mice.
Purpose of the Study:
- To describe the formalin test's characteristics, including stimulus properties and behavioral measurement.
- To interpret changes in nociceptive behavior observed during the formalin test.
- To discuss factors that may influence formalin test results, such as ambient temperature.
Main Methods:
- Description of the formalin stimulus and its application.
- Measurement and interpretation of changes in nociceptive behavior.
- Analysis of early and late phases of the formalin response.
Main Results:
- The formalin test elicits distinct early (C-fiber activation) and late (inflammation, spinal cord changes) phases.
- Late-phase responses in mice are temperature-dependent, suggesting peripheral factors influence results.
- Observing multiple behavioral variables aids in assessing motor or sensorimotor function.
Conclusions:
- The formalin test is a valuable method for studying nociception, offering insights into pain mechanisms.
- Understanding influencing factors like temperature and inflammation is crucial for accurate interpretation.
- The test's two-phase response provides a comprehensive model for pain research.