Effects of Diazeniumdiolates (NONOates) and Methylene Blue on the Reduction of Postoperative Adhesion in Rats

Abstract

We investigated the effects of spermine NONOate (SPER/NO), diethylenetriamine NONOate (DETA/NO) and methylene blue for preventing postoperative adhesion in a rat uterine horn model. Before operations, rats were randomly assigned into 6 groups, each composed of 12 rats. These were the sham, control, normal saline, SPER/NO, DETA/NO and methylene blue groups. Each rat was anesthetized with ketamine hydrochloride (40 mg/kg i.v.). The abdominal wall was shaved; the surgical site was scrubbed with povidone iodine and rinsed with sterile saline 3 times before surgery. Under sterile conditions, a 3-cm vertical midline incision was made in all groups. In the sham group, we closed the abdominal wall without any procedure. In the other groups, a 2-cm segment of each uterine horn was injured in 10 spots on the antimesenteric surface using unipolar cautery. Before the final abdominal closure, no adjuvant therapy was administered intraperitoneally to the rats in the control group; 2 ml of normal saline solution, 1% methylene blue solution, SPER/NO (0.5 mg/ml) and DETA/NO (0.1 mg/ml) were instilled into the uterine horns of the rats in the respective groups. The incision was closed with a running 4-0 monofilament delayed absorbable suture in a single layer of muscle and fascia in a running pattern, excluding the peritoneum, and in the covering layer of skin in an interrupted pattern, in all groups. Two weeks after the surgery, all animals were killed, second laparotomies were performed, and the extent and severity of adhesions were determined by a blinded examiner. The adhesion scores of the sham group were significantly lower than those of the other groups (p < 0.05). In the methylene blue, SPER/NO and DETA/NO groups, adhesion scores were significantly lower than in the normal saline and control groups (p < 0.05). However, there were no significant differences related to the extent and severity scores of adhesions between the methylene blue, SPER/NO and DETA/NO groups (p > 0.05). This study showed that SPER/NO, DETA/NO and methylene blue administered at the end of surgery reduced the adhesion formation in a rat uterine horn model.