No increase in blood-brain barrier permeability after intraperitoneal injection of endotoxin in the rat

Reactions mediated by the brain are part of the response to intraperitoneal administration of endotoxin, a model of gram-negative bacterial infection. To test the hypothesis that a compromised blood-brain barrier (BBB) may contribute to these reactions, the integrity of the BBB was measured following lipopolysaccharide administration. Rats received intraperitoneal injections of 50 microg/kg or 2 mg/kg of endotoxin. Brain uptake of a macromolecular vascular marker, 3H-labelled rat serum albumin, and of a poorly permeable low molecular weight substance, [14C]sucrose, was then measured with the intravenous bolus injection method. Compared to controls, neither dose of endotoxin affected the BBB permeability for these tracers. This was true when brain uptake was measured 5 min or 2 h after lipopolysaccharide injection. It is concluded that intraperitoneal endotoxin even at a high dose does not acutely disrupt the BBB.