Cilostazol restores endothelial function and reduces platelet hyperactivity via PKA/ENOS/PKG and NRF2 signaling in experimental metabolic syndrome

Introduction Metabolic syndrome (MS) is characterized by obesity, hypertension, hyperinsulinemia, and dyslipidemia, conditions associated with endothelial dysfunction and platelet hyperactivity that increase cardiovascular risk. Cilostazol (CZ) is a selective phosphodiesterase-3 (PDE3) inhibitor. Although PDE3 inhibition exerts antiplatelet and vasodilatory actions, the mechanistic interplay between vascular redox balance, endothelial signaling, and platelet function in MS remains poorly defined. Purpose Investigate whether subchronic PDE3 inhibition with cilostazol restores vascular and platelet homeostasis in experimental MS through coordinated modulation of nitric oxide–dependent and antioxidant signaling pathways. Methods Spontaneous hypertensive rats (SHR) were randomized into four groups (n=8/group): a control group (SHR) and control group treated with CZ (100mg/kg) (SHR+CZ) and fed a standard chow diet; (MS) group, fed a hypercholesterolemic diet; and (MS+CZ) group, fed a hypercholesterolemic diet and received CZ. The experimental protocol lasted 12 weeks, with CZ or vehicle administered by gavage once daily for 30 days. Systolic blood pressure was assessed, blood samples were collected for platelet aggregation and biochemical analyses, and thoracic aortas were excised. CEUA/UFF1479140219. Data was analyzed using one-way ANOVA followed by post-hoc Bonferroni multiple comparison test, p<0.05. Results MS group increased Δ body mass (SHR: 94.20±4.20g vs. MS: 109.30±3.54g) and elevated serum total cholesterol (SHR:90.58±4.38 vs. MS:124.70±4.56 mg/dL), glucose (SHR: 205.30± 20.15 vs. MS: 271.10±13.39 mg/dL) and hepatic triglycerides (SHR: 164.70±6.89 vs. MS: 249.7±18.21 mg/dL). CZ did not exert lipid-lowering effects but significantly reduced systolic pressure (MS: 201.80±1.88 vs. MS+CZ: 190.00±3.60 mmHg). Endothelium-dependent relaxation was reduced in MS (SHR: 58.04±3.04% vs. MS: 43.11±1.83%), whereas MS+CZ showed increased maximal relaxation (MS+CZ: 85.76±5.67%). The wall-to-lumen ratio was increased in MS and reduced in MS+CZ group (MS: 2.99±0.31 vs. MS+CZ: 2.32±0.34). MS disrupted NO-dependent signaling and antioxidant defenses, as demonstrated by downregulation of PKA/eNOS/PKG and Nrf2-mediated pathways. Notably, CZ normalized these pathways. Platelet aggregation induced by ADP (0.5µM) and collagen (0.5µg/mL) was increased in MS (ADP: SHR: 43.67±1.90% vs. MS: 50.63±4.31%;collagen: SHR: 51.27±1.78% vs. MS: 77.13±3.76%) and reduced in MS+CZ group (ADP: MS+CZ: 29.00±5.43%;collagen: MS+CZ: 57.11±4.19%). Conclusion CZ treatment exerted hypotensive, vasodilatory, and antiplatelet effects, suggesting potential therapeutic benefit in MS through modulation of the PKA/eNOS/PKG and Nrf2/KEAP1/Catalase/GPx signaling pathways. These findings identify a mechanistic link between endothelial protection and platelet inhibition and support PDE3 inhibition as a promising strategy to counteract cardiometabolic vascular disease.