The effects of oral linagliptin (3 mgkg−1; a kind gift from Boehringer Ingelheim Pharmaceuticals, Ingelheim, Germany) and metformin (200 mgkg−1; Sigma Aldrich, Poole, UK) on the development of HFD/STZ induced changes in mechanical hindpaw withdrawal thresholds were quantified, with the drugs administered from day 4 until day 40 and compared to saline vehicle (HFD/Veh/saline: n = 8; HFD/STZ/saline: n = 8; HFD/STZ/linagliptin: n = 7; HFD/STZ/metformin: n = 6).
The effects of oral daily pioglitazone (10 mgkg−1, in 1% methylcellulose; Tocris Cookson, Bristol, UK) versus vehicle on the development of HFD/STZ induced changes in mechanical hindpaw withdrawal thresholds were quantified once diabetes was established, from day 21 to day 49 after STZ treatment (n = 10-11 per group).
The dose of 3 mgkg−1 of linagliptin was used as this dose has been reported to improve glucose control when given once daily in animal models of diabetes [26 (link)]. In addition this dose significantly increased plasma GLP-1 in diet-induced obese rats and mice [27 (link), 28 (link)] and caused 67–80% DPP-4 inhibition [28 (link)]. The doses of 200 mgkg−1 of metformin and 10 mgkg−1 of pioglitazone were selected as these doses prevent the development of, or reverse established, pain hypersensitivity when given orally in rats [29 (link)–32 (link)].
The effects of oral daily pioglitazone (10 mgkg−1, in 1% methylcellulose; Tocris Cookson, Bristol, UK) versus vehicle on the development of HFD/STZ induced changes in mechanical hindpaw withdrawal thresholds were quantified once diabetes was established, from day 21 to day 49 after STZ treatment (n = 10-11 per group).
The dose of 3 mgkg−1 of linagliptin was used as this dose has been reported to improve glucose control when given once daily in animal models of diabetes [26 (link)]. In addition this dose significantly increased plasma GLP-1 in diet-induced obese rats and mice [27 (link), 28 (link)] and caused 67–80% DPP-4 inhibition [28 (link)]. The doses of 200 mgkg−1 of metformin and 10 mgkg−1 of pioglitazone were selected as these doses prevent the development of, or reverse established, pain hypersensitivity when given orally in rats [29 (link)–32 (link)].