SAAD Centre for Pharmacy and Diabetes, Biomedical Sciences Research Institute, University of Ulster, Cromore Road, Coleraine BT52 1SA, Northern Ireland, UK.
SAAD Centre for Pharmacy and Diabetes, Biomedical Sciences Research Institute, University of Ulster, Cromore Road, Coleraine BT52 1SA, Northern Ireland, UK.
Eur J Pharmacol. 2014 Nov 15;743:69-78. doi: 10.1016/j.ejphar.2014.09.018. Epub 2014 Sep 22.
Oxyntomodulin (Oxm) possesses beneficial biological actions for the potential treatment of obesity-diabetes. However, rapid inactivation by dipeptidyl peptidase-4 (DPP-4) results in a short half-life, hindering therapeutic applicability. In the present study, six Oxm analogues namely, (Thr(2))Oxm, (Asp(3))Oxm, (Aib(2))Oxm, (d-Ser(2))Oxm, (N-acetyl)Oxm and (d-Ser(2))Oxm-Lys-γ-glutamyl-PAL were synthesised and tested for DPP-4 stability and biological activity. Native Oxm, (Thr(2))Oxm and (Asp(3))Oxm were rapidly degraded by DPP-4, while (Aib(2))Oxm, (d-Ser(2))Oxm, (N-acetyl)Oxm and (d-Ser(2))Oxm-Lys-γ-glutamyl-PAL were resistant to degradation. All peptides stimulated cAMP production (P<0.01 to P<0.001) in GLP-1-R, but not in GIP-R, transfected cells. In glucagon-R transfected cells, all peptides except (N-acetyl)Oxm and (Thr(2))Oxm evoked significant cAMP generation. Similarly, all analogues, except (N-acetyl)Oxm, exhibited prominent (P<0.05 to P<0.001) insulinotropic activity in BRIN BD11 cells. When administered in conjunction with glucose to normal mice only native Oxm, (Aib(2))Oxm and (d-Ser(2))Oxm significantly (P<0.05 to P<0.01) increased overall plasma insulin levels. The corresponding glycaemic excursion was significantly (P<0.05 to P<0.001) lowered by all Oxm peptides, barring (N-acetyl)Oxm. Further investigations revealed persistent glucose-lowering and insulin-releasing actions of (d-Ser(2))Oxm-Lys-γ-glutamyl-PAL. Studies in GIP- and GLP-1-receptor KO mice with (Aib(2))Oxm, (d-Ser(2))Oxm, and (d-Ser(2))Oxm-Lys-γ-glutamyl-PAL highlighted the importance of GLP-1 receptor signalling for the beneficial glucose homoeostatic actions of these analogues. All peptides, except (N-acetyl)Oxm, possessed significant appetite suppressive effects in mice. These data highlight the significant therapeutic promise of enzymatically stable Oxm-based peptides, particularly with position 2 modifications, for the treatment of obesity-diabetes.
氧抑素（Oxm）具有治疗肥胖症-糖尿病的有益生物学作用。然而，其半衰期较短，因为其被二肽基肽酶-4（DPP-4）快速失活，从而阻碍了治疗应用。本研究合成了六种 Oxm 类似物，即（Thr(2))Oxm、（Asp(3))Oxm、（Aib(2))Oxm、（d-Ser(2))Oxm、（N-乙酰）Oxm 和（d-Ser(2))Oxm-Lys-γ-谷氨酰-PAL，并对其 DPP-4 稳定性和生物活性进行了测试。天然 Oxm、（Thr(2))Oxm 和（Asp(3))Oxm 被 DPP-4 迅速降解，而（Aib(2))Oxm、（d-Ser(2))Oxm、（N-乙酰）Oxm 和（d-Ser(2))Oxm-Lys-γ-谷氨酰-PAL 则具有抗降解性。所有肽都刺激了 GLP-1-R 中的 cAMP 产生（P<0.01 至 P<0.001），但不刺激 GIP-R 中的 cAMP 产生。在胰高血糖素-R 转染细胞中，除（N-乙酰）Oxm 和（Thr(2))Oxm 外，所有肽都引起了显著的 cAMP 生成。同样，除（N-乙酰）Oxm 外，所有类似物在 BRIN BD11 细胞中都表现出显著的（P<0.05 至 P<0.001）胰岛素分泌活性。当在正常小鼠中与葡萄糖一起给药时，只有天然 Oxm、（Aib(2))Oxm 和（d-Ser(2))Oxm 显著（P<0.05 至 P<0.01）增加了整体血浆胰岛素水平。所有 Oxm 肽都显著（P<0.05 至 P<0.001）降低了相应的血糖升高，除（N-乙酰）Oxm 外。进一步的研究揭示了（d-Ser(2))Oxm-Lys-γ-谷氨酰-PAL 持续的降血糖和释放胰岛素作用。在 GIP- 和 GLP-1-受体 KO 小鼠中研究（Aib(2))Oxm、（d-Ser(2))Oxm 和（d-Ser(2))Oxm-Lys-γ-谷氨酰-PAL 强调了 GLP-1 受体信号对这些类似物有益的血糖稳态作用的重要性。除（N-乙酰）Oxm 外，所有肽在小鼠中均具有显著的食欲抑制作用。这些数据突出了基于氧抑素的酶稳定肽在治疗肥胖症-糖尿病方面的重要治疗前景，特别是 2 位修饰的肽。
