Effects of LPS Immune Challenge on TNF-α Expression and Microglial Activation in the Hippocampus of Female Rats (2024)

Undergraduates: Maya Arora, Mahlet Gebrekidan, Mia Keller, Hari Pinapaka

Faculty Advisor: Shveta Parekh
Department: Psychology and Neuroscience

---

Tumor necrosis factor-alpha (TNF-α) is a pro-inflammatory cytokine released by microglia and other immune cells in the brain in response to stress. Inflammatory cytokines released by damaged microglia are thought to contribute to the pathology of neurodegenerative diseases like Alzheimer’s Disease (AD). For example, TNF-α released by hippocampal microglia has been shown to impair working memory and learning. However, prior research has primarily used male subjects. We examined TNF-α release and microglia activation in the CA1 region of the hippocampus in response to lipopolysaccharide (LPS) immune challenge in female rats. No differences in microglial process length or soma size were found between LPS and control conditions, but Iba-1 cell counts were significantly higher in the LPS condition. TNF-α cell counts were not significantly different between LPS or control conditions. Rats treated with LPS saw a significant increase in TNF-α and Iba-1 colocalization, suggesting that LPS activated microglia, which released TNF-α.