Age differences in the response to the formalin test in rats.
We report the results of a study designed to assess age differences in the response to the formalin test, a model of tissue injury and inflammation, while controlling for differences in weight and motoric abilities in three groups of adult male Long-Evans rats: young (3 months old), middle-aged (18 months old), and old (24 months old). The first part of the study assessed initial differences in responsivity and found that the middle-aged group showed the greatest response, whereas the young and old groups did not differ from each other. In the second part of the study, the young and middle-aged animals were followed for a 4-month period. The formalin test was repeated at 2-month intervals. These results indicate that there may be an age-associated change in the sensitivity to tonic pain and that this sensitivity may peak at mid-life.
Gagliese
L
L
Department of Psychology, McGill University, Montreal, Quebec, Canada. lucy.gagliese@utoronto.ca
Melzack
R
R
D017677:Age Distribution; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D008297:Male; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement; D051381:Rats