THE AMOUNT OF FREE CORTICOSTERONE IS INCREASED DURING LIPOPOLYSACCHARIDE-INDUCED FEVER

RICARDO CABRERA; S. MECHIEL KORTE; EEF G.W.M. LENTJES; FRED ROMIJN; EDUARD SCHBNBAUM; ALEJANDRO DE NICOLA; E. RON DE KLOET

LIFE SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2000 vol. 66 p. 553 - 562

0024-3205

The relation between lipopolysaccharide (LPS)-induced fever and bioavailability of corticosterone (B) was examined in male Wistar rats. Animals were injected with LPS (2.5 mgkg i.p.) or saline and core temperature and heart rate were monitored continuously using a biotelemetry system. Blood samples were withdrawn from freely moving rats via jugularcatheters for estimation of total and free plasma B. LPS induced a long-lasting increase (24-48 h) in core temperature and B secretion and a short-lasting increase (90 min) in heart rate. LPS-induced fever was accompanied by asignificant increase in the free/total B ratio. In contrast, an acute injection of B, which resulted in circulating B levels similar to those found atIer LPS, did not affect the free/total B ratio. The important role of LPS-induced fever in the hormone secretion pattern and the equilibrium between free and total B was tinther demonstrated in an in vitro study showing that an increase in thetemperature by 3°C elevated the free B fraction and the free/total B ratio of plasma samples with concentrations of B in the physiological range (S-40 ug/dl). Taken together, these findings indicate that during LPS-induced fever there is an increase in the amount of biologically available B. Exposure of glucocorticoid-sensitive targets to elevated levels of free B could contribute tothe restoration of homeostasis that is disturbed during inflammation.