[Effects of low-dose insulin on oxidation-reduction in rat organs after major burns]

To explore the effects of low-dose insulin on oxidation-reduction of heart and kidney in rats immediately after severe burns.

Twenty four male Sprague-Dawley (SD) rats were randomly divided into 3 groups of sham burn, burn and treatment (n = 8 each). The sham burn group was placed into 37 °C warm water for 15 seconds to simulate burn process and received no fluid replacement. The burn and treatment groups were immersed into (95 ± 0.5) °C hot water for 15 seconds to make a rat model of 30% total burn surface area, III degree burn injury and immediately received an intraperitoneal injection of physiological saline (40 ml/kg). At the same time, a subcutaneous injection of insulin (1.0 U×kg(-1)×d(-1)) was given in the treatment group and a subcutaneous injection of same-volume physiological saline in the burn group. The rats were sacrificed after 24 post-scald hours (PSH). Abdominal aortic blood was collected for an analysis of blood glucose. The oxidation and antioxidation parameters of heart and kidney, such as malondialdehyde (MDA), xanthine oxidase (XO), myeloperoxidase (MPO), total superoxide dismutase (T-SOD), superoxide dismutase 1, 2 (SOD1, 2), catalase (CAT) and glutathione peroxidase (GPx), were detected by spectrophotometry.

Compared with the sham burn group, MDA content, XO and MPO activities of heart and kidney were significantly higher in the burn group (all P < 0.05); in the treatment group, MDA content and XO activity of heart were significantly lower than the burn group ((0.85 ± 0.07) vs (1.11 ± 0.07) nmol/mg, (69.72 ± 1.94) vs (77.21 ± 2.10) U/g) while the MPO activities of heart and kidney were significantly lower (all P < 0.05).compared with the sham burn group, the activities of T-SOD, CAT, GPx of heart and kidney were significantly lower in the burn group, SOD1 activity of kidney was significantly lower, but SOD2 activity of kidney was significantly higher while SOD2 activity of heart was significantly lower (all P < 0.05); Compared with the burn group, the activities of T-SOD and SOD1 of heart in the treatment group were significantly higher ((83.5 ± 2.5) vs (79.6 ± 3.2), (62.8 ± 2.3) vs (58.8 ± 3.0) U/mg), CAT and GPx activity of heart and kidney were significantly higher (all P < 0.05). Compared with the sham burn group, blood glucose in the burn and treatment group were significantly higher ((7.81 ± 0.30), (7.19 ± 0.22) vs (6.30 ± 0.24) mmol/L) and blood glucose in the treatment group was significantly lower than the burn group((7.81 ± 0.30) mmol/L)(all P < 0.05).

During an early stage, a low-dose insulin may intervene in heart tissue lipid peroxidation of severely burned rats. And differences exist in the effects of oxidation-reduction between heart and kidney.