Serotonin receptor, 5-HT1B, regulates amyloid beta-induced eNOS signaling impairment in human umbilical vein endothelial cells

Background: Serotonin (5-HT) is a neuronal hormone and is implicated in Alzheimer’s disease (AD). While 5-HT1B receptors modulate vascular tone, their influence on endothelial nitric oxide synthase (eNOS) under AD-like conditions is unclear. This study investigates the role of 5-HT1B receptors in regulating the eNOS pathway in HUVEC exposed to amyloid-beta (Aβ). Methods: HUVEC were treated with 10 µM Aβ 1-42 or DMSO for 24 hours to mimic AD conditions. A 5-HT1B receptor antagonist (SB 224289, 200 nM) or DMSO was added 1 hour before Aβ treatment. Then, protein levels of eNOS and associated signaling markers were assessed via Western blotting. Results: The protein expression of phosphorylated eNOS (p-eNOS) was significantly reduced in HUVEC treated with Aβ+DMSO compared to CON+DMSO. Treatment with the 5-HT1B receptor antagonist significantly increased p-eNOS levels compared to Aβ+DMSO. Total eNOS (t-eNOS) levels showed no significant differences between groups. Similarly, phosphorylated Akt (p-Akt) expression was significantly lower in Aβ+DMSO-treated HUVEC compared to CON+DMSO, but the 5-HT1B receptor antagonist restored p-Akt levels. No significant differences were observed in total Akt (t-Akt), phosphorylated AMPK (p-AMPK), or total AMPK (AMPK) across groups. Conclusion: Aβ treatment disrupts the Akt/eNOS signaling pathway, contributing to endothelial dysfunction. Inhibition of 5-HT1B receptors restores Akt/eNOS activity suggesting their potential as therapeutic targets for AD-related vascular dysfunction. Further research is needed to explore its underlying mechanisms. UH CLASS Research Progress Grant This abstract was presented at the American Physiology Summit 2025 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.