engleski

Pancreatic islet surface and share of insulin granules after streptozotocin treatment in wild-type and Tff3 knock-out mice

Trefoil Factor 3 (Tff3) is a small peptide mainly expressed in gastrointestinal epithelial cells with a known role in the protection and repair of the mucosal barrier. It promotes cellular migration and angiogenesis. Tff3 is also found expressed in pancreas islet cells where it co-localizes with insulin and some-glucagon-expressing cells [1]. Some studies indicate that Tff3 could be involved in islet-cell proliferation [2]. To investigate the effect of Tff3 deficiency on the integrity of the pancreas we have performed a study on a novel congenic Tff3-/- C57Bl6NCrl mouse strain using a multiple low-dose streptozotocin (STZ) protocol [3]. STZ is selectively toxic to insulin-producing pancreatic β cells and is commonly used to induce Type 1 diabetes (T1D) in animal models. 7 week-old Tff3-/- male and female mice and wild type controls were administered low 50 mg/kg, multiple intraperitoneal STZ injections (for 5 consecutive days) We have monitored weight and blood glucose levels during the experiment and after 6 weeks of STZ induced hyperglycemia, mice were sacrificed. Pancreases were collected and tissue was fixed in 4% paraformaldehyde and embedded into paraffin. The organs were cut into 6 µm sections. 3 different sections through the whole pancreas, up to 1 mm apart were taken for each animal, and 2 largest pancreatic islets found on the section were used for measurements. Sections were deparaffinized and stained using Gomori’s aldehyde fuchsin for pancreatic beta-granules. 6 digital photographs were taken per animal, islets were separated from the rest of the tissue in GIMP software, and islet surface and beta granule surface were measured using FIJI software. Brightfield microscopy showed only a small number of detectable islets in pancreatic tissue. There was no significant difference in average pancreatic islet surface in a share of beta granules in the islets among the examined groups. Although, there were no differences in pancreas tissue between groups, during the experiment Tff3-/- male and female mice had statistically reduced body weight and higher mortality rate compared to WT animals. These results indicate an important role of Tff3 in response to STZ treatment but its exact role remains yet to be determined. 1. Jackerott, M. ; Lee, Y.C. ; Møllgård, K. ; Kofod, H. ; Jensen, J. ; Rohleder, S. ; Neubauer, N. ; Gaarn, L.W. ; Lykke, J. ; Dodge, R. ; et al. Trefoil factors are expressed in human and rat endocrine pancreas: Differential regulation by growth hormone. Endocrinology 2006, 147, 5752–5759, doi:10.1210/en.2006-0601. 2. Fueger, P.T. ; Schisler, J.C. ; Lu, D. ; Babu, D.A. ; Mirmira, R.G. ; Newgard, C.B. ; Hohmeier, H.E. Trefoil factor 3 stimulates human and rodent pancreatic islet β-cell replication with retention of function. Mol. Endocrinol. 2008, 22, 1251–1259, doi:10.1210/me.2007-0500. 3. Like, A.A. ; Rossini, A.A. Streptozotocin-induced pancreatic insulitis: New model of diabetes mellitus. Science (80-. ). 1976, 193, 415–417, doi:10.1126/science.180605.

Tff3 ; Pancreas ; Pancreatic islets ; Streptozotocin

This work was supported by Croatian Science Foundation grant IP-06-2016-2717 and “Young researchers career development project – training of doctoral students” of the Croatian Science Foundation funded by the European Union from the European Social Fund (I.Bazina)