Effect And Related Mechanism Of Progesterone On The Survival Of Ischemic Random Skin Flaps In Rats

Objective:Clinically,random skin flap has been one of conventional techniques for repairing tissue defects.However,random skin flap contains no major vessels,once the length-to-width ratio excess 1.5-2:1,partial or complete necrosis of distal random skin flap will occur,thereby limit the clinical use of random skin flap.Progesterone is widely known as a female sex hormone,and exogenous progesterone is used to treat women who experience repeat abortions and irregular menstruation.It has been reported that progesterone could increase vascular endothelial growth factor(VEGF)expression,decrease inflammatory cytokine levels and obtain a strong antioxidant activity.The purpose of this study was to investigate the effect and underlying mechanism of progesterone on the survival of ischemic random flaps in rats.Method:1?Modified McFarlane ischemic random skin flap model was designed in rats and male Sprague-Dawley rats were randomly divided into progesterone-treated group and control group according to random number table to received either progesterone(10 mg/kg)or saline(10 mg/kg)by intraperitoneally injection once a day for seven days.Random skin flap was equally divided into pedicle region(? region)?central region(? region)and distal region(? region)depending on blood supply.Surviving condition was observed and survival rate of flaps in each group was measured after operation.In addition,the second day after operation,levels of malondialdehyde(MDA)and superoxide dismutase(SOD)were measured;H&E staining was performed for tissue histopathological examination;VEGF expression was detected by immunohistochemistry;Flap blood flow was measured by Laser-Doppler flowmeter;Flap vasculature was assessed by angiography after Lead oxide-gelatin injection.Results:1.The seventh day after operation,the percentage of surviving area of random skin flap in treatment group was estimated to be(81.62±1.86)%,which was significantly higher than that in control group(49.78±1.36)%,there was statistically significant difference.(P<0.01).2.On the second day after operation,the progesterone group had a statistically significant difference in the expression of SOD(61.40 ± 2.29)u·mg-1 protein-1 compared with saline group(29.95 ± 2.91)u·mg-1 protein-1.The expression of MDA in the treatment group was(16.25 ±3.08)nmol·mg-1·protein-1,which was significantly lower than the saline group(62.32± 5.38)nmol·mg-1·protein-1.3?Seven days after operation,as shown in H&E staining,the area(?)of flaps in progesterone-treated group showed abundant neovascularization compared to control group,microvessels density in the middle region of flaps in the progesterone-treated group was(33.64±3.04)/mm2,significantly higher than that in the control group(15.95±3.65)/mm2.4?The middle region of flaps in the progesterone-treated group showed significantly lower neutrophil infiltration(30.10 ± 2.67/mm2)than those in the saline group(44.80 ± 3.54/mm2),with significant difference between two groups(P<0.01).5?The positive expression of VEGF in the middle of the flap in the progesterone group was(3479 ± 68)IA,the positive expression of VEGF in normal saline group was(1923 ± 43)IA,with statistical significance(P<0.01).6?Blood perfusion in pedicle region(? region)?central region(? region)and distal region(? region)in the treatment group are(406.82±15.21)PU?(210.45±6.93)PU?(109.95±4.91)PU,respectively,all of which were significantly higher than in the control group.7?Gelatin-lead oxide film showed angiogenesis of the central flap and distal flap in progesterone group was statistically significant.Conclusion:Progesterone can promote the survival of ischemic random flaps in rats.The mechanism may be related to 1?progesterone can upregulate the expression of VEGF,stimulate neovascularization,increase the blood supply,thereby promoting the survival of the flap;2?progesterone can reduce tissue inflammatory response,thus promoting the survival of random skin flap;3?progesterone can inhibit lipid peroxidation,alleviate the ischemia-reperfusion injury of flap and promote the survival of random skin flap.