Hippocampal Microglia Activation Induced by Acute Pancreatic Injury in Rats.

Background: Acute pancreatitis is an inflammation of the pancreatic glandular parenchyma that causes injury with or without the destruction of pancreatic acini. Clinical and experimental evidence suggest that certain systemic proinflammatory mediators may be responsible for initiating the fundamental mechanisms involved in microglial reactivity. Here, we investigated the possible repercussions of acute pancreatitis (AP) on the production of inflammatory mediators in the brain parenchyma focusing on microglial activation in the hippocampus.

Methods: The acute pancreatic injury in rats was induced by a pancreas ligation surgical procedure (PLSP) on the splenic lobe, which corresponds to approximately 10% of total mass of the pancreas. Blood samples were collected via intracardiac puncture for the measurement of serum amylase. After euthanasia, frozen or paraffin-embedded brains and pancreas were analyzed using qRT-PCR or immunohistochemistry, respectively.

Results: Immunohistochemistry assays showed a large number of Iba1 and PU.1-positive cells in the CA1, CA3, and dentate gyrus (DG) regions of the hippocampus of the PLSP group. TNF-α mRNA expression was significantly higher in the brain from PLSP group. NLRP3 inflammasome expression was found to be significantly increased in the pancreas and brain of rats of the PLSP group. High levels of BNDF mRNA were found in the rat brain of PLSP group. In contrast, NGF mRNA levels were significantly higher in the control group versus PLSP group.

Conclusion: Our findings suggest that AP has the potential to induce morphological changes in microglia consistent with an activated phenotype.