The long-term protective effect of hypothermia and gradual detorsion on ovarian tissue in adnexal torsion/detorsion model in rats

Abstract

Introduction: Ischemia in ovarian torsion and subsequent reperfusion has significant effects on fertility in the long term. The most important reason for these changes is thought to be a reperfusion injury rather than ischemia. We aimed to evaluate whether the reperfusion injury following ovarian detorsion could be reduced by hypothermia and intermittent reperfusion.

Materials and methods: Forty adult female rats were divided into five groups as follows: Sham (Sh) (n = 8), torsion detorsion (control TD) (n = 8), progressive reperfusion "gradual detorsion" (GD) (n = 8), hypothermia (H) (n = 8) and the progressive reperfusion + hypothermia (GD + H) (n = 8). In all rats, except for the Sh group, the left ovary was rotated counter clockwise 1080° and fixed to the abdominal wall by three 5-0 non-absorbable sutures followed by the closure of the laparotomy. After 30 h, reperfusion was achieved following the detorsion of the ovaries. In both the control TD and H groups, the torsed ovaries were detorsed. H group, however, was subjected to hypothermia with ice packs 30 min before and during the detorsion. Tissue temperature was kept constant at 4 °C, controlled by a digital thermometer. In the GD group, the torsed ovary and pedicle were detorsed by 360°, followed by a 5 min pause. This procedure was repeated twice until a complete detorsion was achieved. GD + H group underwent hypothermia with ice packs 30 min before the procedure and the torsed ovary and pedicle were detorsed by 360°. After a 5 min pause, we repeated this process twice to provide full detorsion. The tissue temperature was constantly held at 4 °C. In the hypothermia groups, we applied hypothermia for an additional 30 min after detorsion and then left the rats at normal body temperature during reperfusion. We followed the rats in all groups for 60 days. Then we excised the left ovaries of all rats through laparotomy and spared some of the ovaries for biochemical and pathological examination. Intracardiac blood was taken at the end of the procedure and it was sent to the biochemical laboratory to assess oxidative stress markers. Finally, all the animals were sacrificed with high-dose of anesthesia.

Results: Evaluation of the results revealed that oxidative stress markers were significantly lower, and antioxidant parameters were higher in the experimental groups compared with the control TD group (p < 0.05). Histopathologically, we found that tissues were preserved in GD, H, GD + H groups (p < 0.05). When we compared the groups among each other, both biochemical and histopathological values in GD + H group showed that the tissue was preserved from oxidative damage, albeit the difference did not reach a level of significance.

Discussion: Several studies have shown that both hypothermia and intermittent reperfusion protect tissue from IR damage in the early period. However, as far as we know there is no study on long-term outcomes of both practices. Our study showed that both hypothermia and intermittent reperfusion alone protect tissue from IR damage in the long term. However, it did not show the superiority of the combination of both methods compared to that of individual application. The advantages of these methods lie in their easy application and cost-effectiveness. We believe that our study will serve as a base for future studies on the subject.

Keywords: Adnexal torsion; Hypothermia; In vitro study; Long-term effect; Reperfusion injury.