Diabetes mellitus (DM), a metabolic disorder, is considered one of the top five causes of death globally, affecting as many as 150 million people worldwide. In diabetic subjects, use of zinc oxide nano-particles (ZnONPs) leads to reduction in blood glucose level and higher expression of insulin receptors. However, the structural changes introduced by them in pancreas, liver and kidney of diabetic rats are largely undocumented. The current study, therefore, was designed to report the modifications effectuated in the histomorphometry of the above- mentioned organs of diabetic rats through oral use of ZnONPs.
The study included 25 Wistar rats, housed in stainless steel cages in the animal shed. The rats were kept in environmentally controlled room with temperature of 24 ± 5 ºC, under a 12 h light: 12 h dark cycle and provided free access to water and food. The rats were divided into five groups. Diabetes was induced by injection of alloxan in four groups, leaving one group as negative control. The treatment of ZnONPs was mixed in the feed of three diabetic groups at 15mg/kg, 25mg/kg and 50mg/kg respectively doses for 15 days. At the termination of the trial, pancreas, liver and kidney were dissected out, fixed and processed for histomorphometry. Diameter and density of pancreatic islets of Langerhans, number and diameter of alpha, beta cells, renal cortex width, glomerular diameter, proximal and distal convoluted tubules diameter, wall to lumen thickness ratio of proximal and distal convoluted tubules, Bowman’s capsule basement membrane thickness, central vein diameter of liver, width of hepatocyte cords and Kupffer cells count was studied.
The morphometric results showed that size of pancreatic islets of Langerhans, diameter and number of beta cells per islet was lower (p<0.05) in positive control group and ZnONPs treated groups G1, G2, and G3 than in negative control group. There was no significant difference of islet size, diameter and number of beta cells between G1, G2, G3 groups and positive control group. Histomorphometric evaluation of alpha cells showed that alpha cells count and diameter remained the same in all groups. Pancreatic islet density was similar among all groups.
Glomerular diameter in control positive group was similar (p>0.05) to control negative group. Glomerular diameter increased (p>0.05) in ZnONPs treated groups (G1, G2, G3) as compared to both control groups. The cortex width decreased (p<0.05) in positive control group as compared to negative control, increased (p>0.05) in ZnONPs treated groups (G1, G2, G3) as compared to both control groups. The cortex width decreased (p<0.05) in positive control group as compared to negative control group Following treatment with ZnONPs, thickness increased (p<0.05) in G2 and G3 groups compared to positive control group but was similar to that of negative control group. Proximal convoluted tubule diameter increased (p<0.05) in ZnONPs treated groups as compared to both control groups. The distal convoluted tubules diameter increased in G1, G2 and G3 groups as compared to control groups. Wall to lumen ratio of distal tubules showed no significant difference among groups. Bowman’s capsule basement membrane thickness significantly increased in the positive control group and G1, G2 and G3 groups as compared to negative control group.
Central vein diameter of liver increased (p<0.05) in positive control group as compared to negative control group, while it was found similar between G1, G2 and G3 groups and positive control group. The hepatocyte cords width increased in positive control group as compared to negative control group. In G1, G2, and G3 groups, the hepatocyte cords width was smaller (p<0.05) than in control positive group. The number of Kupffer cells significantly increased in positive control group as compared to negative control group. The Kupffer cell count was lower (p<0.05) in G1, G2 and G3 groups than the positive control group. Microscopy of liver sections, stained with PAS staining, showed minimum glycogen deposition in hepatocytes of positive control group and treated groups as compared to negative control group.
In conclusion, histomorphometric evaluation showed that ZnONPs did not improve tissue micro-architecture of pancreas and kidney, rather deterioration of the parenchyma was observed. However, use of ZnONPs ameliorated the liver histology to some extent.