Glucagon-like peptide 2 (GLP-2) is an intestinotropic peptide that binds to GLP-2 receptor (GLP-2R), a class-B G protein-coupled receptor. The GLP-2R antagonist GLP-2(3-33) has relatively high partial agonistic activity, and there are as yet no ideal known potent GLP-2R antagonists. We therefore prepared several truncated forms of human GLP-2 and characterized them by binding and reporter assays to find antagonists more potent than GLP-2(3-33). We found that GLP-2(11-33) was the most potent orthosteric GLP-2R antagonist, with binding activity almost equal to those of GLP-2 and GLP-2(3-33) and weaker intrinsic agonistic activity than GLP-2(3-33). GLP-2(11-33) retained weak agonistic activity toward human, cynomolgus monkey, dog, and Syrian hamster GLP-2Rs. However, it had no agonistic activity toward rat GLP-2R. GLP-2(11-33) potentiated the agonistic activity of an ago-allosteric modulator of GLP-2R, compound 1 (N-[1-(2,5-dichlorothiophen-3-yl)-2-(phenylsulfanyl)ethylidene]hydroxylamine), synergistically toward human GLP-2R. In the case of rat GLP-2R, GLP-2(11-33) decreased the agonistic activity of compound 1, although GLP-2 and GLP-2(3-33) increased this activity additively. These findings suggest that the binding sites of the ago-allosteric modulator and GLP-2 overlap, at least in rat GLP-2R. GLP-2(11-33) is a novel, useful tool for analyzing the mode of action of agonists and ago-allosteric modulators of GLP-2R.
Even when the daily blood pressure mean is acceptable, too large a circadian amplitude of blood pressure largely increases cardiovascular disease risk. Autogenic training (N = 11), a non-pharmacologic intervention capable of lowering an excessive blood pressure variability, may be well-suited for MESOR-normotensive patients diagnosed with circadian-hyper-amplitude-tension (CHAT). Not all anti-hypertensive drugs affect blood pressure variability. Accordingly, long-acting carteolol (N = 11) and/or atenolol (N = 8) may be preferred to captopril retard (N = 13), nilvadipine (N = 8), or amlodipine (N = 7) for midline-estimating statistic of rhythm (MESOR)-hypertensive patients with CHAT. Prospective outcome studies are needed to assess whether the relative merits of these treatments are in keeping with their effects on blood pressure and blood pressure variability.
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