Influence of type-4 dipeptidyl peptidase inhibition on endothelium-dependent relaxation of aortae from a db/db mouse model of type 2 diabetes: a comparison with the effect of glimepiride
Received 13 May 2019
Accepted for publication 19 July 2019
Published 16 August 2019 Volume 2019:12 Pages 1449—1458
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Amy Norman
Peer reviewer comments 3
Editor who approved publication: Dr Antonio Brunetti
Owen L Woodman,1 Jacinta M Ortega,1 Joanne L Hart,1 Thomas Klein,2 Simon Potocnik1
1School of Health and Biomedical Sciences, RMIT University, Bundoora, VIC, Australia; 2Department of Cardiometabolic Diseases Research, Boehringer Ingelheim Pharma, Biberach, Germany
Correspondence: Owen L Woodman
Baker Heart & Diabetes Institute, PO Box 6492, Melbourne 3004, Australia
Tel +61 38 532 1917
Purpose: The aim of this study was to investigate the effects of the type-4 dipeptidyl peptidase (DPP-4) inhibitors linagliptin and vildagliptin as well as the sulfonylurea glimepiride on endothelium-dependent relaxation of aortae from female db/db mice with established hyperglycemia to determine whether these treatments were able to attenuate diabetes-induced endothelial dysfunction.
Materials and methods: The mice were treated with glimepiride (2 mg/kg po per day, weeks 1–6, n=12), glimepiride plus vildagliptin (glimepiride 2 mg/kg po per day, weeks 1–6; vildagliptin 3 mg/kg po per day, weeks 4–6, n=11), glimepiride plus linagliptin (glimepiride 2 mg/kg po per day, weeks 1–6; linagliptin 3 mg/kg po per day, weeks 4–6, n=11) or linagliptin (3 mg/kg po per day, weeks 1–6, n=12). Endothelium-dependent relaxation using acetylcholine was assessed in the absence and presence of pharmacological tools (TRAM-34 1 μM; apamin 1 μM; N-nitro-L-arginine [L-NNA] 100 μM; 1H-[1,2,4]oxadiazolo [4,3-a]quinoxalin-1-one [ODQ] 10 μM) to distinguish relaxation mediated by nitric oxide (NO).
Results: Linagliptin was associated with a significant improvement in endothelium-dependent relaxation (ACh Rmax; db/db 41±1%, linagliptin 73±6%, p<0.05). The enhanced response was maintained in the presence of TRAM-34+ apamin (ACh Rmax; db/db 23±6%, linagliptin 60±6%, p<0.01), ie, when the endothelium-dependent relaxation was mediated by NO. There was no evidence for a contribution from KCa channel opening to responses under any conditions. Glimepiride had no effect on endothelium-dependent relaxation when given alone (ACh Rmax 38±3%). The addition of linagliptin or vildagliptin to glimepiride did not significantly improve endothelium-dependent relaxation. All treatments caused some decrease in aortic superoxide production but the effect of linagliptin was significantly greater than glimepiride (linagliptin 534±60 relative luminescence unit [RLU], glimepiride 1471±265 RLU, p<0.05).
Conclusion: Linagliptin is superior to glimepiride in regard to the preservation of endothelium-dependent relaxation in the presence of hyperglycemia and the improvement in endothelial function in response to linagliptin treatment is associated with greater antioxidant activity compared to glimepiride.
Keywords: diabetes, DPP-4 inhibitor, endothelium-dependent relaxation, glimepiride, linagliptin, reactive oxygen species
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