Hypertriglyceridemia promotes dysfunctions in high-density lipoprotein increasing the cardiovascular risk

Abstract Hypertriglyceridemia is associated with several metabolic diseases. The triglycerides (TG) disrupt the cholesterol reverse transport and contribute to increased levels of low-density lipoprotein (LDL). High-density lipoprotein (HDL) acts in cholesterol reverse transport as an anti-inflammatory and antioxidant. This study aims to investigate the role of hypertriglyceridemia in the functionality of HDL. Individuals were divided into 4 groups based on high or low HDL-c and triglycerides levels. Biochemical and anthropometric analysis were performed. This study demonstrated that triglycerides promote dysfunctions on HDL, increasing the cardiovascular risk. Blood pressure was higher in subjects with low HDL. Women presented higher levels of HDL-c and low percentage of fat mass. The highest levels of triglycerides were observed in older age. In addition, high levels of triglycerides were associated with higher total cholesterol and LDL-c levels, non-HDL-c, non-esterified fatty acids, and blood glucose, increasing in the ratio of non-HDL-c/HDL-c and ApoB/ApoA-I. The increase of triglycerides levels progressively impairs the antioxidant capacity of HDL, probably due to a higher occurrence of fatty acid peroxidation in individuals with hypertriglyceridemia. Patients with high HDL and low TG levels increased the Lag Time. Furthermore, a positive correlation was found between TG versus HDL particle size, variables that depend on age and anthropometric parameters.

Tyramine exerts hypolipidemic and anti-obesity effects in vivo

Abstract Obesity and dyslipidemia are conditions often associated with cardiovascular risk, inflammation, oxidative stress, and death. Thus, a new approach has been highlighted to promote research and development of pharmacological tools derived from natural sources. Among the most widely studied groups of substances, polyphenols such as tyramine stand out. This study investigated hypolipidemic and anti-obesity properties of tyramine. Oral toxicity evaluation, models of dyslipidemia and obesity were used. To induce dyslipidemia, Poloxamer-407 (P-407) was administered intraperitoneally. In the hypercholesterolemic and obesity model, specific diet and oral tyramine were provided. After 24h of P-407 administration, tyramine 2 mg/kg (T2) decreased triglycerides (TG) (2057.0 ± 158.5 mg/dL vs. 2838 ± 168.3 mg/dL). After 48h, TG were decreased by T2 (453.0 ± 35.47 vs. 760.2 ± 41.86 mg/dL) and 4 mg/kg (T4) (605.8 ± 26.61 760.2 ± 41.86 mg/dL). T2 reduced total cholesterol (TC) after 24h (309.0 ± 11.17 mg/dL vs. 399.7 ± 15.7 mg/dL); After 48h, 1 mg/kg (T1) (220.5 ± 12.78 mg/dL), T2 (205.8 ± 7.1 mg/dL) and T4 (216.8 ± 12.79 mg/dL), compared to P-407 (275.5 ± 12.1 mg/dL). The treatment decreased thiobarbituric acid reactive substances and nitrite in liver, increased superoxide dismutase, reduced the diet-induced dyslipidemia, decreasing TC around 15%. Tyramine reduced body mass, glucose, and TC after hypercaloric feed. Treatment with 5 mg/L (0.46 ± 0.04 ng/dL) and 10 mg/L (0.44 ± 0.02 ng/dL) reduced plasma insulin (1.18 ± 0.23 ng/dL). Tyramine increased adiponectin at 5 mg/L (1.02 ± 0.02 vs. 0.83 ± 0.02 ng/mL) and 10mg/L (0.96 ± 0.04 ng/mL). In conclusion, tyramine has low toxicity in rodents, has antioxidant effect, reduces plasma triglycerides and cholesterol levels. However, further studies should be conducted in rodents and non-rodents to better understand the pharmacodynamic and pharmacokinetic properties of tyramine