Plasma cholesterol modulate functions of neutrophils in streptozotocin-induced type 1 diabetic rats

Objectives: Our previous study demonstrated neutrophil dysfunction in streptozotocin (STZ)-induced diabetic rats. This study was aimed to investigate the biochemical indices such as plasma levels of cholesterol, triglycerides, creatinine, urea, alanine transaminase and aspatate transaminase in diabetic and control rats and thus, investigate their relationship with the previously studied neutrophil functions. Methods: Diabetes was induced in Long Evans rats by an intraperitoneal injection of citrate buffer dissolved streptozotocin (STZ). Age matched control rats were injected with citrate buffer only. Neutrophils were isolated from blood using standard dextran sedimentation followed by Ficoll-Hypaque centrifugation; morphological changes in neutrophils, their ability to reduce nitroblue tetrazolium (NBT) dye and phagocytic activity from both the groups of rats were evaluated formerly. Biochemical indices were measured by standard colorimetric methods. Results: The average levels of glucose, triglycerides, cholesterol, creatinine, urea in the plasma of diabetic and control rats were 302.6 ± 87.5 vs 100.7 ± 11.5 mg/dL, 174.9 ± 18.6 vs 82.2 ± 10.2 mg/dL; 250.8 ± 22.3 vs 165.2 ± 24.1 mg/dL; 0.94 ± 0.19 vs 0.81 ± 0.05 mg/dL; 77.1 ± 9.7 vs 26.8 v 5.8 mg/dL, respectively. The mean values of aspartate transaminase (AST) and alanine transaminase (ALT) in diabetic and control rats were 141.4 ± 28.0 vs 61.6 ± 18.6 IU/L and 61.4 ± 13.6 vs 48.5 ± 6.0 IU/L, respectively. Biochemical parameters measured in diabetic rats varied significantly (p < 0.001) compared to those of control rats. Plasma indices such as triglycerides, cholesterol, creatinine, urea, AST and ALT had no relation with the functions of neutrophils. However, multidimensional scaling found a close relation between plasma cholesterol and phagocytic activity of neutrophils from diabetic rats. Ability to reduce NBT dye was closely related to the morphology of the activated neutrophils. On the other hand, levels of plasma glucose were distantly related to the functions of neutrophils. Conclusion: Thus, important liver and kidney functions indices, lipid profile parameters were significantly altered in diabetic rats and plasma cholesterol modulated the phagocytic activity of neutrophils.