Haematological and blood biochemical changes induced by the administration of low doses of Escherichia coli lipopolysaccharide in rabbits

Abstract

The aim was to investigate the haematological and blood biochemistry changes of adult rabbits after two intravenous administrations of low-doses of E. coli lipopolysacharide (LPS). Six clinically healthy rabbits were distributed through a cross over design to experimental groups: Group 1 (LPS) treated with two intravenous doses of 1 μg/kg bw of E. coli LPS at 6 h intervals. Group 2 (Control) treated with an equivalent volume of saline solution (SS) at similar intervals. Rectal temperature (T°R), serum concentrations of interleukin-6 (IL-6), C-reactive protein (CRP), haemogram, and the activity of enzymes aspartate aminotransferase (AST) and gamma glutamil transferase (GGT) were measured before and after LPS or SS administration. The administration of LPS in rabbits induced significant increases in IL-6 and CRP concentrations. Leukopenia associated to significant decreases of monocytes, lymphocytes and platelet count, with no significant changes in neutrophil count, were observed at 4 and 8 h after LPS administration. There were significant increases in total leukocytes and neutrophils count at 12 and 24 h. No significant changes (P > 0.05) were observed in mean values of PCV, total proteins, albumin and in the activity of enzymes AST and GGT. The administration of low doses of E. coli LPS induces a fast increase in body temperature, haematological and biochemical shifts, which are milder and have a lower intensity and shorter than previous reports in rabbits treated with high doses of LPS. These changes seem to be consistent with an initial inflammatory response induced by a gram-negative infection.