Elisas

Animals in which the dorsal hippocampus was injected with propranolol (5 μg per side) were sacrificed either under basal conditions or 30, 60, and 120 min after conditioning with 1.4‐mA shocks. Trunk blood and the dorsal hippocampus were quickly collected from animals subjected to each of the conditions. Rat hippocampal samples were dissected on dry ice and homogenized on ice to generate lysates (1 mg wet weight tissue into 40 μl of 0.01 N HCl, 1 mmol/L EDTA, and 4 mmol/L sodium metabisulfite). After centrifugation of blood in EDTA‐coated tubes at 2000 rpm for 10 min, the supernatant was stored at −80°C until the assay was performed. Norepinephrine was extracted from brain tissues according to the manufacturer's instructions, and the dried extracts were stored at −80°C until the assay was performed. Plasma and hippocampal levels of norepinephrine or epinephrine were determined by specific enzyme‐linked immunosorbent assays (ELISAs; Abnova, Taipei, Taiwan), according to the manufacturer's instructions.

Lipopolysaccharide binding protein (LBP) and plasminogen activator inhibitor-1 (PAI-1) protein levels were measured in peripheral plasma of humans and plasma from portal vein of mice using commercially available ELISAs (Abnova, Taiwan and LOXO, Germany), respectively, as detailed by the manufacturer. Arginase activity in proximal small intestine was measured, as previously described [21 (link)].

LBP was quantified from clarified and 800-fold diluted fasting heparin plasma with ELISAs (Abnova, Taipei City, Taiwan; cat number KA0448) as described elsewhere [28 (link)].