Therapeutic administration of orlistat, rosiglitazone, or the chemokine receptor antagonist RS102895 fails to improve the severity of acute pancreatitis in obese mice.

OBJECTIVE: Currently, there is no therapy for severe acute pancreatitis (AP) except for supportive care. The lipase inhibitor orlistat, the peroxisome proliferator-activated receptor γ agonist rosiglitazone, and the chemokine receptor 2 antagonists attenuate the severity of AP in rodents if administered before or at the time of induction of pancreatitis. However, it is unknown whether these treatments are effective if administered therapeutically after induction of pancreatitis. METHODS: Male C57BL6 mice with diet-induced obesity received 2 injections of mrIL-12 (150 ng per mouse) and mrIL-18 (750 ng per mouse) intraperitoneally at 24-hour intervals. The mice were injected 2, 24, and 48 hours after the second injection of IL-12 + IL-18 with orlistat (2 mg per mouse), rosiglitazone (0.4 mg per mouse), RS102895 (0.3 mg per mouse), or vehicle (20 µL of DMSO and 80 µL of canola oil) and euthanized after 72 hours. RESULTS: Orlistat decreased intra-abdominal fat necrosis compared with vehicle (P < 0.05). However, none of the drug treatments produced significant decreases in pancreatic edema, acinar necrosis, or intrapancreatic fat necrosis. CONCLUSIONS: Drugs previously shown to improve the severity of AP when given before or at the time of induction of pancreatitis failed to do so when administered therapeutically in the IL-12 + IL-18 model.

Kinetic parameters and lactate dehydrogenase isozyme activities support possible lactate utilization by neurons.

Lactate is potentially a major energy source in brain, particularly following hypoxia/ischemia; however, the regulation of brain lactate metabolism is not well understood. Lactate dehydrogenase (LDH) isozymes in cytosol from primary cultures of neurons and astrocytes, and freshly isolated synaptic terminals (synaptosomes) from adult rat brain were separated by electrophoresis, visualized with an activity-based stain, and quantified. The activity and kinetics of LDH were determined in the same preparations. In synaptosomes, the forward reaction (pyruvate + NADH + H(+ )--> lactate + NAD(+)), which had a V (max) of 1,163 micromol/min/mg protein was 62% of the rate in astrocyte cytoplasm. In contrast, the reverse reaction (lactate + NAD(+ )--> pyruvate + NADH + H(+)), which had a V (max) of 268 micromol/min/mg protein was 237% of the rate in astrocytes. Although the relative distribution was different, all five isozymes of LDH were present in synaptosomes and primary cultures of cortical neurons and astrocytes from rat brain. LDH1 was 14.1% of the isozyme in synaptic terminals, but only 2.6% and 2.4% in neurons and astrocytes, respectively. LDH5 was considerably lower in synaptic terminals than in neurons and astrocytes, representing 20.4%, 37.3% and 34.8% of the isozyme in these preparations, respectively. The distribution of LDH isozymes in primary cultures of cortical neurons does not directly reflect the kinetics of LDH and the capacity for lactate oxidation. However, the kinetics of LDH in brain are consistent with the possible release of lactate by astrocytes and oxidative use of lactate for energy in synaptic terminals.

The lipophilic iron compound TMH-ferrocene [(3,5,5-trimethylhexanoyl)ferrocene] increases iron concentrations, neuronal L-ferritin, and heme oxygenase in brains of BALB/c mice.

Mismanagement of intracellular iron is a key pathological feature of many neurodegenerative diseases. Our long-term goal is to use animal models to investigate the mechanisms of iron neurotoxicity and its relationship to neurodegenerative pathologies. The immediate aim of this experiment was to determine regional distribution of iron and cellular distribution of iron storage proteins (L- and H-ferritin) and an oxidative stress marker (heme oxygenase-1) in brains of mice fed the lipophilic iron compound (3,5,5-trimethylhexanoyl) (TMH)-ferrocene. We fed male and female weanling BALB/cj mice diets either deficient in iron (0 mg Fe/kg diet), adequate in iron (35 mg Fe/kg diet; control mice), or adequate in iron and supplemented with 0.1 or 1.0 g TMH-ferrocene/kg diet for 8 wk. Iron concentrations in cerebrum were higher in mice fed 1.0 g TMH-ferrocene/kg diet than in control mice (p < 0.05). Liver iron concentrations were eightfold higher in mice fed 1.0 g TMH-ferrocene/kg diet than in control mice (p < 0.0001). L-Ferritin and heme oxygenase-1 expression were elevated in striatum in mice fed 1.0 g TMH-ferrocene/kg diet. We conclude that administration of the lipophilic iron compound TMH-ferrocene leads to subtle perturbations of cellular iron within the brain, potentially representing a model of iron accumulation similar to that seen in various neuropathological conditions.