Lipopolysaccharide (LPS) treatments

There were four treatment groups for each mouse sex and strain: LPS from Salmonella typhimurium (Sigma Aldrich, St. Louis, MO, USA) was dissolved in sterile normal saline for injections. We used three LPS treatment regimens. The first is an intraperitoneal (i.p.) three-injection regimen of 3mg/kg at t = 0, 6, and 24 hours. We have found that this regimen robustly and consistently disrupts the BBB to larger vascular space markers like albumin (MW = 66.5 kDa) in male CD-1 mice, as well as the smaller marker 14C-sucrose (340 Da) [3]. The second and third regimens are single i.p. injections of LPS at 3mg/kg or 0.3mg/kg, which were found to more moderately induce BBB disruption to 14C-sucrose, or to not induce detectable BBB disruption in male CD-1 mice, respectively [3]. The selections of these dosing regimens allow for comparison to previously published data in CD-1 male mice [3]. Control mice received three intraperitoneal (i.p.) injections of sterile normal saline (N.S.), given at t = 0, 6, and 24 hours. All mice were studied 28 hours after the first injection. The first LPS injections were always given in the morning, between the hours of 8:00 and 11:00. Mice were evaluated in 5 identical studies that spanned 11 days, and 2–4 mice from each treatment group from each sex and strain were used in each study, with the exception of one day in which mice from the female 0.3mg/kg single LPS injection group (see below) were reassigned to the 3-injection LPS groups since some mice died as a result of treatment or anesthesia prior to being studied.