Protective Effect Of N-3 Polyunsaturated Fatty Acid On Rat Testis Ischemia-reperfusion Injury And Its Mechanism

Objective: Testicular torsion is an emergency of the urinary system,which is mainly found in children and adolescents.If the treatment is not timely,it may lead to testicular ischemia and necrosis.Testicular ischemia and reperfusion are important pathophysiological features of testicular torsion surgery.Long-term follow-up after the testicular salvage operation showed the ipsilateral testicular atrophy,functional impairment and male infertility.The effect of testicular ischemia reperfusion injury should not be ignored.In addition to early diagnosis and active operation,the application of protective agent is of great significance to prevent testicular ischemia reperfusion injury during testicular torsion and reduction.N-3 polyunsaturated fatty acids(n-3 PUFAs)is an important group of fatty acids,mainly including docosahexaenoic acid(DHA)and eicosapentaenoic acid(EPA).In this study,a rat model of testicular ischemia-reperfusion(I/R)was established by surgery to study the protective effect of n-3 PUFAs on rat testicular ischemia-reperfusion injury and explore its mechanism.Methods: Male puberty SD rats were randomly divided into three groups: sham operation group,I/R group and n-3 PUFAs administration group,with 8 rats in each group.In n-3 PUFAs group,the n-3 PUFAs(1g/kg/day,DHA33%,EPA22%)were intragastrically administered for 14 consecutive days.The sham-operated group and the I/R group were given an equal volume of saline daily for 14 consecutive days.The testicular torsion model was established according to the Turner method.In each group,a left inguinal incision was performed,and the gubernaculum was cut off to free the left testis and spermatic cord.Then,in the sham operation group,the testicle was fixed on the scrotal dartos and the incision was closed.In the I/R and n-3 PUFAs groups,the testicles were rotated clockwise by 720 degrees along the long axis of spermatic cord,and the testicles were properly fixed to maintain the torsion for 2 hours.After the testicular reduction,the testicles were refixed again.Rats were sacrificed after 4 hours and the specimens were collected.The pathological features and differences of the testis tissue were observed under microscope.The levels of oxidative stress markers,including malondialdehyde(MDA)and reactive oxygen species(ROS),and anti-oxidative stress markers,including total antioxidant capacity(T-AOC),catalase(CAT),glutathione(GSH),glutathione/glutathione ratio(GSH/GSSG),superoxide dismutase(SOD),were detected and compared.In addition,the expression level of the nuclear factor erythroid 2–related factor 2(Nrf2)and its downstream antioxidant enzyme,heme oxygenase-1(HO-1)and NAD(P)H-Quinone Oxidoreductase 1(NQO1),were measured.The expression level of Nuclear Factor-kappa B(NF-κ B)was also determined.Results: Compared with the sham operation group,the I/R group showed significant histopathological changes,higher oxidative stress level and lower level antioxidant capacity,the levels of Nrf2 and NF-κ B were highly expressed(P < 0.05).The n-3 PUFAs group had significant higher mean seminiferous tubule diameter compared with the I/R group.The levels of MDA and ROS in testicular tissues of n-3 PUFAs group were significantly lower than those of the I/R group,while the T-AOC,CAT,GSH,GSH/GSSG and CAT levels increased significantly(P< 0.05).Besides,the expression levels of Nrf2,HO-1,and NQO1 were significantly higher and the NF-κB expression level was significantly lower in the n-3 PUFAs treated group than that in I/R group(P<0.05).Conclusion: Testicular torsion reduction showed obvious ischemia reperfusion injury.N-3 PUFAs ameliorated testis damage caused by testicular I/R injury through its antioxidative and anti-inflammatory effects,involving the activation of Nrf2 and the inhibition of NF-κB.