Calcium changes in rabbit CSF during endotoxin, IL-1 beta, and PGE2 fever

Abstract

New Zealand rabbits were chronically incannulated in the lateral ventricle and cisterna magna to assess the hypothesis that calcium concentration (Ca) of cerebrospinal fluid (CSF) varies during fevers of diverse origin. In normothermic and febrile animals recovering from surgery, CSF Ca was positively and significantly correlated to rectal temperature (TR). IV injection of E. coli endotoxin and ICV injection of human recombinant interleukin 1 beta (hrIL-1 beta) induced a TR rise of 1.7 +/- 0.3 degrees C (mean +/- SEM) and 1.45 +/- 0.25 degrees C, respectively, accompanied by significant increases in CSF Ca. After endotoxin administration, maximal Ca increases ranged between 0.21 and 0.48 mM above basal values in individual animals (p < 0.01), whereas after administration of hrIL-1 beta increases were 0.17 and 0.25 mM (p < 0.05). Acetylsalicylic acid (ASA) countered the fever induced by both endotoxin and hrIL-1 beta administrations and concomitantly antagonized the Ca increase in CSF. HrIL-1 beta-derived nonapeptide was characteristically devoid of pyrogenic effect and did not modify CSF Ca. Although ICV injection of prostaglandin E2 (PGE2) increased TR by 2.1 +/- 0.77 degrees C, it failed to have any effect on CSF Ca. Differently from the other Ca enhancers, PGE2, however, increased CSF protein concentration (protein). These findings suggest that brain calcium metabolism plays a role in fever development and that prostaglandin involvement is only engaged once changes in CSF calcium concentration have taken place.