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Acute Inflammatory and Neuropathic Pain in Lewis and Fischer Rats
Author(s) -
Fecho K.,
Valtschanoff J. G.
Publication year - 2006
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1111/j.1365-2826.2006.01442.x
Subject(s) - neuropathic pain , hyperalgesia , carrageenan , inflammation , medicine , allodynia , endocrinology , sciatic nerve , anesthesia , nociception , receptor , pharmacology
Inbred, histocompatible Lewis and Fischer 344 rats (LEW and FIS) have been used to identify an inverse relationship between hypothalamic‐pituitary‐adrenal (HPA) axis activity and susceptibility to autoimmune and chronic inflammatory disorders, with LEW showing blunted HPA axis activity and increased susceptibility toward the development of autoimmunity and chronic inflammation, and FIS showing the opposite relationship. In the present study, LEW and FIS were used to determine the relationship between HPA axis function and acute inflammatory pain (carrageenan‐induced hindpaw inflammation) and neuropathic pain (partial sciatic nerve ligation; PSNL). The results showed that carrageenan‐induced thermal and mechanical allodynia and hyperalgesia were greater in FIS than in LEW. Similarly, FIS showed more carrageenan‐induced hindpaw swelling and higher levels of myeloperoxidase (a measure of neutrophils) in the carrageenan‐inflamed hindpaw. After PSNL, LEW showed a profound mechanical allodynia and hyperalgesia, whereas mechanical sensitivity in FIS was unaltered. However, FIS, but not LEW, developed thermal allodynia and hyperalgesia after PSNL. These results provide strong evidence for a positive relationship between HPA axis activity and acute inflammatory pain. The results also support a relationship between HPA axis activity and neuropathic pain, but the relationship is complex and may depend on the pain assay.