Reduced ability of neutrophils to produce active oxygen species in streptozotocin-induced diabetic rats

Abstract

We investigated a possible alteration in the ability of neutrophils to produce active oxygen species in streptozotocin (STZ)-induced diabetic rats. The production of superoxide of the neutrophils was assessed by luminol-dependent chemiluminescence (LDCL) after the stimulation by opsonized zymosan. Four days after STZ (60 mg/kg, ip) injection, blood glucose level increased by 399 +/- 9 mg/dl and the LDCL activity was significantly reduced in diabetic rats (control group: 5.12 +/- 1.53 KC/min2/10(6) cells, STZ group: 1.10 +/- 0.07 KC/min2/10(6) cells, p less than 0.01). At Day 17, blood glucose level was maintained high (598 +/- 8 mg/dl) and the LDCL activity (1.01 +/- 0.39 KC/min2/10(6) cells) was almost at the same level as that of diabetic rats at Day 4. Subcutaneous injection of insulin for 10 consecutive days increased the LDCL activity of diabetic rats in a dose-dependent manner (vehicle: 0.82 +/- 0.27 KC/min2/10(6) cells, 0.04 U/day: 1.61 +/- 0.09 KC/min2/10(6) cells, 0.40 U/day: 1.99 +/- 0.47 KC/min2/10(6) cells, 4.00 U/day: 3.33 +/- 0.43 KC/min2/10(6) cells). The data obtained herein indicate that an increased susceptibility to bacterial infection in diabetic rats results from impaired neutrophil function to produce active oxygen species.