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Role for the cholecystokinin‐A receptor in fever: a study of a mutant rat strain and a pharmacological analysis
Author(s) -
Ivanov Andrei I.,
Kulchitsky Vladimir A.,
Romanovsky Andrej A.
Publication year - 2003
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j..2003.t01-1-00941.x
Subject(s) - endocrinology , medicine , cholecystokinin , receptor antagonist , cholecystokinin receptor , receptor , agonist , chemistry , lipopolysaccharide , antagonist , thermoregulation
The involvement of the cholecystokinin (CCK)‐A receptor in fever was studied. The polyphasic febrile responses to lipopolysaccharide (LPS; 10 μg kg −1 , i.v. ) were compared between wild‐type Long‐Evans (LE) rats and the CCK‐A‐receptor‐deficient Otsuka LE Tokushima Fatty (OLETF) rats. The response of the wild‐type rats was biphasic, which is typical for LE rats. Phases 1 and 2 of the response of the OLETF rats were similar to those of the LE rats, but the OLETF rats also developed a robust phase 3. This late enhancement of the febrile response could reflect either the absence of the A receptor per se or a secondary trait of the mutant strain. To distinguish between these possibilities, we conducted a pharmacological analysis. We studied whether the normally low phase 3 of LE rats can be enhanced by a CCK‐A‐receptor antagonist, sodium lorglumide (4.3 μg kg −1 min −1 , 120 min, i.v. ), and whether the normally high phase 3 of Wistar rats can be attenuated by a CCK‐A receptor agonist, sulphated CCK‐8 (up to 0.17 μg kg −1 min −1 , 120 min, i.v. ). The dose of sodium lorglumide used was sufficient to increase food intake (to block satiety), but it did not affect the fever response. In both febrile and afebrile rats, CCK‐8 induced dose‐dependent skin vasodilatation and decreased body temperature, but it failed to produce any effects specific for phase 3. We conclude that the exaggeration of phase 3 in OLETF rats reflects a secondary trait of this strain and not the lack of the CCK‐A receptor per se . None of the three known phases of the febrile response of rats to LPS requires the CCK‐A receptor.