Effect of sulfur dioxide exposure on histopathology and morphometry of pancreatic islet cells and glycemic indices in Wistar rats

Sulfur dioxide (SO2) is a ubiquitous air pollutant. Recent studies suggest that SO2 is a momentous risk factor for diabetes mellitus (DM). The present investigation aimed to evaluate the effects of SO2 exposure on histopathology and morphometry of pancreatic islet cells and serum glycemic indices in rats. Sixteen male Wistar rats were divided equally into SO2 and control groups. SO2 group was exposed to 10 parts per million (ppm) SO2 for 5 weeks (6 days a week, 3 h/day) and control group to filtered air for the same time as SO2 group. Blood serums were collected and pancreatic tissue isolated. Glycemic indices were measured. Pathological and morphometric changes were studied in the pancreatic tissues. Exposure to SO2 caused a significant increase in blood glucose but did not significantly change insulin and HbA1c serum levels and HOMA-IR. There were significant differences in vascular congestion (p= 0.02) and insulitis (p= 0.04) between the groups. SO2 inhalation significantly reduced beta cell number and beta-alpha cell ratio compared with the control group (p=0.03 and p<0.0001, respectively). These findings suggest that SO2 exposure damages pancreatic tissue which subsequently influences either the incidence of DM or the trend of diabetic complications.