Sitagliptin effects on inflammation and fibrosis of exocrine pancreas of diabetic ZDF rats. Histopathological observation of exocrine inflammation in 26 week-old animals (images A-C): (A) Micrograph of a normal exocrine parenchyma of lean control ZDF rat; (B) The untreated diabetic rats exhibiting severe inflammatory infiltrate, amid the acini of the exocrine parenchyma (grade 3 inflammatory lesions); (C) Normal exocrine parenchyma with no inflammatory signs in the exocrine pancreas of sitagliptin-treated diabetic ZDF rats. Histopathological observation of exocrine fibrosis in 26 week-old animals (images D-F): (D) Normal pancreatic duct in a lean control ZDF rat; (E) An extremely thickened, grade 3, fibrotic duct, which overextends the microscopic field (interrupted line), with numerous neocanaliculi in the duct wall, .present in an untreated diabetic ZDF rat; (F) Improvement of duct fibrosis from grade 3 to grade 1 (full line) in a 6 weeks sitagliptin treated diabetic ZDF rat. Semiquantitative evaluation of inflammation (graph G) and fibrosis (graph H): (G) Exocrine pancreatic inflammation revealed only a slight descent in sitagliptin treated animals in relation to its untreated counterparts; (H) Sitagliptin presented a trend to decrease the duct fibrosis increment (p < 0.05) found in the untreated ZDF rats. Chi-square test with Monte Carlo simulation or exact test (when contingency tables are 2×2) was performed to find out the differences in histomorphological lesions observed in exocrine pancreas (p < 0.05, p < 0.01 and p < 0.001 for one, two or three symbols, respectively; n = 5 per group).