Importantly, after 4

Importantly, after 4.5 months of incretin therapy, none of the mice developed tumors, pancreatitis, or ductal hyperplasia. Fasting glucose was elevated with HFD feeding ( 0.001) [Fig. 4(f); Supplemental Table 5]. Random-fed glucose was higher with long-term glipizide-treated LFD and HFD groups, especially in HFD mice, considering that control HFD-fed mice exhibited elevated ( 0.001) glucose compared with LFD controls [Fig. 4(g); Supplemental Table 5]. This further reveals that continuous long-term glipizide treatment disturbs glucose control in mice. Random-fed glucose in HFD-fed mice was maintained with incretin therapy, equivalent to LFD-fed mice receiving vehicle or incretin therapy. Fasting insulin was increased ( 0.001) in control HFD-fed mice [Fig. 4(h); Supplemental Table 5]. However, fasting insulin was lower with glipizide and incretin therapy compared with control mice with HFD [Fig. 4(h) and 4(i); Supplemental Table 5], consistent with lower insulin requirements due to lower body weight and improved glucose tolerance. Overall, incretin therapy significantly enhanced glucose control during metabolic stress with HFD feeding. Open in a separate window Figure 4. Long-term incretin therapy improves glucose homeostasis even on a HFD. (a) Timing of long-term diabetes therapy (glipizide, exenatide, des-fluoro-sitagliptin, or vehicle [control]), diet administration (low or high fat), GTT, and kill (SAC) in 10-week-old B6.129 F1 hybrid mice. (b) Body weight (in grams) recorded over time with the corresponding area under the curve analysis in (c). (d) Intraperitoneal GTT was performed, with the corresponding area under the curve analysis in (e). (f) Fasting and (g) average random-fed blood glucose (mg/dL). Means standard error of the mean (n = 8C12 animals/group). (h and i) Fasting and random-fed serum insulin (ng/mL). Means standard error of the mean (n = 4C12 animals/group). *** 0.001 vs control within diet (one-way analysis of variance). HFD-induced 0.001) in control HFD-fed mice compared with LFD [Fig. 5(jCl); Supplemental Table 6]. 0.01; *** 0.001 vs control HFD by one-way analysis of variance. HFD-induced 0.001) 0.05; ** 0.01; *** 0.001 vs control HFD by one-way analysis of variance. Open in a separate window Figure 7. DG051 Long-term incretin therapy does not change pancreas weight in HFD-fed mice. (a) Pancreas weight (in milligrams) and (b) pancreas weight (in milligrams) normalized to body weight (in grams) from mice with long-term therapy on a LFD or and HFD. Means standard error of the mean (n = 8C12 animals/group). ** 0.01; *** 0.001 vs control by one-way analysis of variance. Long-term incretin therapy does not alter pancreatic histology in young mice Previous studies suggested that incretin therapy might induce exocrine duct metaplasia (22, 23). As a result, we carried out an extensive study of pancreas histopathology on hematoxylin and eosinCstained slides (Fig. 8; Supplemental Figs. 2C9). A trained rodent pathologist examined 521 pancreas head and tail slides distributed across all four treatment groups on both a LFD and HFD (n = 8C11/group). Slides were evaluated for changes in exocrine duct hyperplasia, atrophy, size, inflammation, and PDG changes (see Methods). Small amounts of tissue necrosis and inflammation were observed sporadically in mice of all Rabbit Polyclonal to DAK groups (Supplemental Tables 8C10). Histopathological changes were focal, mild in severity, and considered incidental, with no relation to any particular treatment. Ductal changes were observed DG051 in only one mouse among all groups. Within a glipizide-treated mouse on a HFD, mild ductular hyperplasia was observed in the pancreas head and was considered secondary to inflammation at the site and most likely unrelated to treatment [Fig. 8(d); Supplemental Table 9]. Subsequently, all pancreas head slides (262 slides) were evaluated to determine the incidence and appearance of PDGs to address concerns reported by Butler (22) study could not be supported (46C49). The main critiques included: (1) T2D groups with our without incretin therapy were not appropriately matched for age, duration, or DG051 advanced stage of diabetes; (2) it was unclear whether some patients actually had type 1 diabetes; (3) there were variable staining and methodological issues for quantification; (4) the observed neuroendocrine tumors and PanIN lesions appear to be due to increasing age rather than incretin therapy; and (5) there were too few samples to adequately interrogate the larger population (46C49). Thus, more extensive analyses across a much larger data set are required to resolve this.