Lipid Droplet Accumulation Accompanied by Oxidative Stress Contributes to Lipotoxicity in the Brainstem of Aged C57BL/6J Mice

Aging is a significant risk factor for cardiovascular diseases, including hypertension and heart failure. Our laboratory previously demonstrated that aging increases blood pressure and is associated with elevated sympathetic nerve activity, but the cellular mechanisms driving this sympatho-excitation remain unclear. Lipid droplets (LD’s) are present in most cells under normal physiological conditions; however their excessive accumulation is increasingly linked to pathological conditions such as Alzheimer’s disease, age-related neurodegeneration and obesity driven neuroinflammation. Recent studies in aging report that brain endothelial cells and microglia accumulate lipid droplets (LD’s) that exhibit pro-inflammatory and senescent phenotypes, but the presence and relevance of LD’s have not been examined in the brainstem, which consists of a key region such as rostral ventrolateral medulla that regulates sympathetic outflow. We hypothesized that lipid droplet accumulation and associated oxidative stress drive lipotoxicity in the aged brainstem. To test this, brainstems from aged (22-month) and young (4-month) C57BL/6J male mice were analyzed for lipid droplet-associated gene expression, oxidative stress markers and lipid peroxidation products. RT-PCR (n=8/group) revealed significantly elevated expression of lipid droplet markers - Plin2 (p < 0.0001), Plin3 (p = 0.0003), and the superoxide-producing enzyme Nox4 (p < 0.0001) in the aged brainstem compared to the young. Dihydroethidium (DHE) staining of brainstem sections (n=3/group) demonstrated enhanced red fluorescence in aged tissue, indicating elevated reactive oxygen species (ROS) levels (p = 0.006). Lipid peroxidation generates reactive aldehydes such as 4-hydroxynonenal (4-HNE) and malondialdehyde (MDA), which readily form adducts with proteins and DNA, driving cellular dysfunction. Consistent with this, competitive ELISA (n=4/group) revealed significantly increased levels of 4-HNE (p = 0.0075) and MDA adducts (p = 0.0096) in aged brainstem compared with young (n = 4/group). Together, these findings indicate that aging shifts brainstem lipid homeostasis toward lipid droplet accumulation and redox imbalance, leading to lipotoxicity that may contribute to neuroinflammation and heightened sympathetic outflow. Ongoing studies will understand glial cell–specific lipid handling pathways and determine how lipotoxicity drives early cellular senescence within the aging brainstem. Support or Funding Information: NHLBI-NIGMS R01HL163775 This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.