Modulation of rat C-reactive protein serum level by dexamethasone and adrenaline--comparison with the response of alpha 2-acute phase globulin.

The alpha-2-acute phase globulin (alpha 2-APG) of the rat is one of the best investigated acute phase proteins. Glucocorticoids as well as catecholamines could be characterized as potent modulators of alpha 2-APG concentration. The aim of this study was to investigate whether the C-reactive protein (CRP), another acute phase protein important in human medicine, is also influenced by adrenal hormones and if so whether the effects are receptor-mediated or not. Adrenaline and isoproterenol (a beta-agonist) increase the blood level of alpha 2-APG and CRP dose-dependently probably due to a mechanism involved in the sequence of an inflammatory process, too. Dexamethasone administration led to a sigmoidal dose-response curve in the case of alpha 2-APG whereas a biphasic sinusoidal-like dose-response curve was obtained for CRP. Doses around 0.01 mg/kg (2 X 10(-8) Mol/kg) increased while doses around 0.1 mg/kg (2 X 10(-7) Mol/kg) decreased the CRP serum level. By combination of the agonists (adrenaline, dexamethasone) with the respective antagonists (propranolol, a beta-blocking agent and RU 38486, a glucocorticoid antagonist) the agonist-induced changes in concentration of CRP and alpha 2-APG could be suppressed. Therefore it can be assumed that the hormone effects are receptor-mediated ones. The reactions of arthritic or inflamed rats pretreated with RU 38486 indicate a considerable influence of endogenous glucocorticoids on blood levels of acute phase proteins. Taken together, both alpha 2-APG and CRP are modulated by adrenal hormones.(ABSTRACT TRUNCATED AT 250 WORDS)