[Effects of San-huang-sheng-fu oil on peripheral circulatory disorders and foot ulcers in diabetic rats and the mechanisms].

OBJECTIVE: To observe the effects of San-huang-sheng-fu oil (S) on peripheral circulatory disorders and foot ulcers in diabetic rats and the relevant mechanisms.

METHODS: (1) Twenty-five Wistar rats were divided into non-diabetes (N), diabetes and sham treatment (DS), metformin (M), S, and combined treatment (CT) groups according to the random number table, with 5 rats in each group. Rats in group N were injected with sodium citrate buffer solution, while rats in the other 4 groups were injected with 10 mg/mL streptozotocin to induce diabetes. In post injection week (PIW) 3, feet of rats in all the 5 groups received an ice-cold stimulation to induce peripheral circulatory disorders. From PIW 9 to 12, rats in groups N and DS were gavaged with saline and applied with sesame oil on pelma of both hind limbs; rats in group M were gavaged with diluted M and applied with sesame oil on pelma of both hind limbs; rats in group S were gavaged with saline and applied with S on pelma of both hind limbs; rats in group CT were gavaged with diluted M and applied with S on pelma of both hind limbs. In PIW 9 before treatment (hereinafter referred to as before treatment) and post treatment week (PTW) 1, 2, and 3, plantar temperature and hot pain threshold of rats were detected by infrared thermometer and foot tester respectively. (2) Another 25 rats were divided and induced with diabetes (expect for group N) as above. In PIW 9, rats in the 5 groups were inflicted with foot ulcer in the left pelma of hind limb by steam and received the corresponding treatment. On post treatment day (PTD) 3, 7, 21, and 35, the general condition and area of wounds were observed and measured respectively. All the rats were sacrificed on PTD 35, and wound tissue was collected for histomorphological observation and determination of expressions of cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) using HE staining and immunohistochemical staining respectively. Data were processed with analysis of variance for repeated measurement, one-way analysis of variance, and Bonferroni post hoc test.

RESULTS: (1) The experiment of peripheral circulatory disorders in diabetes. Compared with the plantar temperature of rats in group N, except for that in group CT in PTW 2 and groups M, S, and CT in PTW 3 (with t values from 0.258 to 2.647, P values above 0.05), the plantar temperature of rats with diabetes in the 4 groups at each time point was lowered significantly (with t values from 2.811 to 6.066, P values below 0.05). Compared with the plantar temperature of rats in group DS, except for that in group CT in PTW 2 and 3 significantly increased (with t values respectively 3.419 and 2.863, P values below 0.05), the plantar temperature of rats in groups M, S, and CT showed no significant difference at each time point (with t values from 0.128 to 1.654, P values above 0.05). The plantar hot pain threshold of rats was significantly decreased in group N than in the other 4 groups before treatment and group S in PTW 1 (with t values from 2.836 to 4.456, P values below 0.05). The plantar hot pain thresholds of rats in groups M, S, and CT were close to the hot pain threshold in group DS (with t values from 0.312 to 1.611, P values above 0.05). (2) The experiment of diabetic foot ulcers. Edema existed in all the wounds of rats on PTD 3. The wound areas of all the rats continued to increase with swelling and scar formation on PTD 7. On PTD 21, the scar of rats in groups N, S, and CT fell off; the wounds of rats in group DS were still swollen; scar of rats did not fall off with dark red in the skin around the wound in group M. On PTD 35, wounds of rats in groups N, S, and CT were nearly healed; while wounds of rats in groups DS and M were still swollen and the scar around the wound failed to fall off. On PTD 3 and 7, the wound areas of rats with diabetes in the 4 groups were close to those in group N (with t values from 0.111 to 1.476, P values above 0.05). On PTD 21, the wound area of rats in group DS was significantly larger than that in group N (t=5.502, P<0.01), while the wound areas of rats with diabetes in the other 3 groups were close to the area in group N (with t values from 0.544 to 1.676, P values above 0.05). On PTD 21, the wound area of rats in group M was close to that in group DS (t=1.895, P>0.05), while the wound areas of rats in groups S and CT were significantly smaller than the area in group DS (with t values respectively 5.809 and 3.426, P<0.05 or P<0.01). On PTD 35, the wound areas of rats in groups DS and M were significantly larger than the area in group N (with t values respectively 8.495 and 4.108, P values below 0.01), while the wound areas of rats in groups S and CT were close to the area in group N (with t values respectively 0.291 and 2.195, P values above 0.05). On PTD 35, the wound area of rats in group M was close to that in group DS (t=0.897, P>0.05); while the wound areas of rats in groups S and CT were significantly smaller than the area in group DS (with t values respectively 6.923 and 6.583, P values below 0.01). On PTD 35, the structures of wound tissue were in better integrity with less inflammatory cells and more regularly arranged collagen fibers around the wounds of rats in groups N, S, and CT than in groups DS and M. On PTD 35, the expression levels of COX-2 and VEGF in the wounds of rats in group DS [respectively (222±89)% and (55±12)%] were close to those in group M [respectively (137±24)% and (94±36)%, with t values respectively 3.046 and 2.653, P values above 0.05]. On PTD 35, the expression level of COX-2 in the wounds of rats in group DS was significantly higher than the expression levels of COX-2 in groups N, S, and CT [respectively (100±35)%, (91±42)%, and (109±17)%, with t values from 4.039 to 4.653, P values below 0.01], while the expression level of VEGF in the wounds of rats in group DS was significantly lower than the expression levels of VEGF in groups N, S, and CT [respectively (100±28)%, (143±12)%, and (120±13)%, with t values from 3.363 to 5.905, P<0.05 or P<0.01].

CONCLUSIONS: S can improve the plantar temperature decrease and pain dysesthesia of rats caused by diabetic peripheral circulatory disorders. It also can promote wound healing of diabetic foot ulcers in rats with down-regulation of COX-2 and up-regulation of VEGF.