Diurnal rhythm in endotoxin-induced mortality in mice: correlation with proinflammatory factors and lack of circadian variation.

MARPEGAN, L; LEONE, MJ; KATZ, ME; SOBRERO, P; GOLOMBEK, DA

CHRONOBIOLOGY INTERNATIONAL

TAYLOR & FRANCIS INC

Año: 2009 vol. 26 p. 1430 - 1442

0742-0528

Many immune parameters exhibit daily and circadian oscillations, including the number of circulating cells and levels of cytokines. Mice also have a differential susceptibility to lipopolysaccharide (LPS)-induced endotoxic shock depending of the administration time in a Light:Dark (LD) cycle (Halberg et al., 1960). We replicated these results in LD, but we did not find differences in LPS-induced mortality in constant darkness. Animals challenged with LPS showed only transient effects in wheel locomotor activity rhythm without modifications in circadian period and phase. Levels of several key factors involved in the pathology of sepsis and shock septic were tested in LD. We found that LPS-induced levels of IL-1â, IL-6, JE (MCP-1) and MIP1á were significantly higher at ZT11 (time of maximum of mortality) than at ZT19. Our results indicate that the differences found in mortality dependently of the time LPS-challenge are not directly related with an endogenous circadian clock and that some relevant immune factors in the development of sepsis are higher induced at ZT11, time of maximal LPS-induced mortality.