Increased fructose consumption induces metabolic-syndrome-like pathologies and modulates vasoactivity and the participation of nitric oxide (NO) and hydrogen sulfide (H₂S). We investigated whether a slow-releasing H₂S donor, GYY-4137, could exert beneficial activity in these conditions. We examined the effect of eight weeks of fructose intake on the blood pressure, biometric parameters, vasoactive responses, and NO and H₂S pathways in fructose-fed spontaneously hypertensive rats with or without three weeks of GYY-4137 i.p. application. GYY-4137 reduced triacylglycerol levels and blood pressure, but not adiposity, and all were increased by fructose intake. Fructose intake generally enhanced endothelium-dependent vasorelaxation, decreased adrenergic contraction, and increased protein expression of interleukin-6 (IL-6), tumor necrosis factor alpha (TNFα), and concentration of conjugated dienes in the left ventricle (LV). Although GYY-4137 administration did not affect vasorelaxant responses, it restored disturbed contractility, LV oxidative damage and decreased protein expression of TNFα in fructose-fed rats. While the participation of endogenous H₂S in vasoactive responses was not affected by fructose treatment, the expression of H₂S-producing enzyme cystathionine β-synthase in the LV was increased, and the stimulation of the NO signaling pathway improved endothelial function in the mesenteric artery. On the other hand, chronic treatment with GYY-4137 increased the expression of H₂S-producing enzyme cystathionine γ-lyase in the LV and stimulated the beneficial pro-relaxant and anti-contractile activity of endogenous H₂S in thoracic aorta. Our results suggest that sulfide and nitroso signaling pathways could trigger compensatory vasoactive responses in hypertensive rats with metabolic disorder. A slow H₂S-releasing donor could partially amend metabolic-related changes and trigger beneficial activity of endogenous H₂S.

Background/Objectives: Metabolic syndrome is one of the leading causes of mortality worldwide, with high-fat diet (HFD) intake being a significant driving force. Despite long-term research, new interventions are still being sought to improve cardiovascular disorders associated with metabolic syndrome. Methods: To explore the therapeutic potential of a slow-releasing H₂S donor, we evaluated the effects of 3 weeks of treatment with GYY-4137 on systolic blood pressure (sBP), cardiac parameters, adiposity, selected plasma markers, and the vascular function of the thoracic aortas (TAs) and mesenteric arteries (MAs) isolated from male spontaneously hypertensive rats (SHRs) fed an HFD for 8 weeks. Results: HFD administration induced cardiac remodeling, increased adiposity, and decreased adrenergic contractility in both TAs and MAs. Moreover, although high-fat intake improved TAs relaxation, it decreased aortic protein expression of endothelial NO synthase and the involvement of NO in vasoactive responses of both TAs and MAs. In addition, protein expression of inducible NOS and tumor necrosis factor alpha (TNFα) in aortas was increased, as were plasma levels of chemerin, which has been proposed as a possible link among metabolic and vascular disorders and inflammation. Treatment with GYY-4137 reduced sBP, improved relaxation of the MAs, partially restored the contractility of the TAs, generally restored NO signaling, and decreased the protein expression of the inducible NOS and TNFα, as well as plasma chemerin levels. Conclusions: A slow H₂S-releasing donor could partially ameliorate the metabolic changes induced by increased fat intake during essential hypertension and trigger beneficial vasoactive effects associated with the NO signaling restoration and suppression of inflammation.