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There has been no report about in vivo active cholesterol-lowering dipeptide in any protein origin, despite their potential health benefits. Cattle heart protein hydrolysate ultra-filtrate (HPHU, molecular weight < ca. 1,000 Da peptide mixture) exhibits cholesterol-lowering activity in hypercholesterolemic rats, but the active peptide in HPHU that lowers serum cholesterol levels and its molecular mechanism are unknown. In this study, we separated and purified HPHU to identify a novel cholesterol-lowering dipeptide (phenylalanine-proline, FP) and characterized the mechanism underlying its effects in vivo and in vitro. We identified FP as an active peptide from HPHU by MALDI-TOF mass spectrometry. FP significantly decreased serum total and non-HDL cholesterol and hepatic cholesterol levels in rats. FP significantly increased serum HDL cholesterol, accompanied by a significant decrease in the atherogenic index. FP also significantly increased fecal cholesterol and acidic steroid excretion. Moreover, FP significantly decreased ATP-binding cassette transporter A1 (ABCA1) expression in the rat jejunum and reduced cholesterol absorption in Caco-2 cells. We found a novel cholesterol-lowering dipeptide FP that could improve cholesterol metabolism via the down-regulation of intestinal ABCA1. The cholesterol-lowering action induced by FP was disappeared in PepT1KO mice. FP-induced cholesterol-lowering action is mediated via PepT1 in mice. [ABSTRACT FROM AUTHOR]

Purpose: To demonstrate the protective effect of glucagon-like peptide 1 (GLP-1) signaling on the cardiovascular system, we conducted this study to show that the GLP-1 receptor analog (lixisenatide) could inhibit abdominal aortic aneurysm (AAA) development in rats. Methods: Lixisenatide was injected subcutaneously 7 days after aneurysm preparation. We evaluated reactive oxygen species (ROS) expression by dihydroethidium staining and 8-hydroxydeoxyguanosine (8-OHdG; the oxidation product of DNA) by immunohistochemical staining. We also analyzed the effect of GLP-1 signaling on the inflammatory response. Histopathological examination was done on day 28, and the AAA dilatation ratio was calculated. Results: On day 14, ROS expression and 8-OHdG-positive cells in the aneurysm walls were seen to have been significantly decreased by lixisenatide treatment. Western blot analysis showed decreased ERK expression. There was significantly reduced tumor necrosis factor-α mRNA expression in the aneurysm walls and CD68-positive cell infiltration in the aneurysm walls. On day 28, it was evident that the lixisenatide had dramatically reduced aneurysm development in the rats. Conclusion: GLP-1 elevation inhibits AAA development in rats through its anti-oxidant and anti-inflammatory effects. Thus, GLP-1 could be a potent pharmacological target for AAA treatment. [ABSTRACT FROM AUTHOR]