Tetrahydropalmatine improves mitochondrial function in vascular smooth muscle cells of atherosclerosis in vitro by inhibiting Ras homolog gene family A/Rho-associated protein kinase-1 signaling pathway.

Background: Tetrahydropalmatine (THP) regulates mitochondrial function in vascular smooth muscle cells (VSMCs) to prevent or alleviate atherosclerosis (AS), with unclear specific mechanism.

Methods: AS models were constructed by oxidized low-density lipoprotein (ox-LDL)-treated VSMCs. Cell counting kit-8 for cell viability, wound scratch assay for cell migration, and flow cytometry for cell cycle, intracellular reactive oxygen species, and mitochondrial membrane potential (MMP) were performed. Malondialdehyde (MDA) and superoxide dismutase (SOD) levels by biochemical kits, oxygen consumption rate (OCR) by seahorse apparatus, apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay (TUNEL) staining, and apoptosis-related expression by western blot were detected. Ras homolog gene family A/Rho-associated protein kinase-1 (RhoA/ROCK1) levels were measured by western blot and ELISA. The RhoA agonist, U46619, was employed to validate mechanism of THP.

Results: THP suppressed cell cycle progression and cell migration whereas alleviating cell viability and oxidative stress, as reduced MDA and enhanced SOD levels in ox-LDL-incubated VSMCs. THP protected mitochondrial function by higher MMP levels and OCR values. Additionally, THP decreased TUNEL-positive cells, Bax, Caspase-3, RhoA, ROCK1, and osteopontin expression, while increased Bcl-2 and smooth muscle myosin heavy chain levels. Furthermore, U46619 intervention antagonized effects of THP.

Conclusion: THP improved mitochondrial function in VSMCs of AS by inhibiting RhoA/ROCK1 signaling pathway.