Protective Effects Of L-arginine On Hepatic And Ovarian Damage In 4-nitrophenol Exposed Rats

The industrial development is consequently accompanied by severe environment pollution,such as the accumulation of chemical pollutants.It has been proved that p-nitrophenol(PNP)as a environmental endocrine disruptor could interfere with the endocrine function,which posed a potential threat to human and animal health.Our previous studies have shown that PNP can not only affect the reproductive function of male rats,but also could cause hepatic oxidative damage in rats.L-arginine(Arg)is an effective antioxidant,it plays an important role in the anti-oxidative stress.Therefore,rat was chosen as experimental objects,to study the protective effects and possible mechanism of Arg on PNP induced injuries in the liver and ovary,which was expected to provide scientific methods for prevention and treatment of PNP poisoning.The main research contents and results are as follows and results are shown as follows:1.The protective effects of arginine against liver damage in PNP-exposed ratsThis experiment is aimed to investigate the ameliorative effects of Arg on rat liver damage induced by PNP.The experiment was arranged as a 2x2 factorial design,including diet type(0 g/kg Arg or 13 g/kg Arg)and PNP injection(100 mg/kg b.w.or the same dose of PBS).A total of 24 female SD rats aged 3 weeks were chosen and divided into 4 groups:CT group(Control+PBS),CTA group(Arg+PBS),PNP group(Control+PNP),PNPA group(Arg+PNP).Dietary Arg and PNP subcutaneous injection were performed simultaneously,and the experiment lasted for 1 week.After the last treatment,all animals were sacrificed and the serum and liver samples were collected.Results showed that compared with CT group,subcutaneous injected PNP(PNP group)reduced average daily gain(ADG)and the liver weight significantly.Liver histological observation presented the illustrations of disorganization,broader interval in hepatic sinusoid and pyknotic nucleus in PNP group.PNP subcutaneous injection(PNP group)increased the concentrations of MDA and H2O2 in liver significantly,while compromised the activity of T-SOD significantly.The serum AST and ALT activities were significantly enhanced in PNP group.The mRNA expression of HO-1 and NQO1 significantly increased.However,compared with PNP group,dietary supplementation of 13 g/kg arginine(PNPA group)increaed ADG significantly,and there was a significant increase in liver weight and liver index.The liver injury was partly repaired.The activities of serum AST and ALT compromised subtly.The activity of T-SOD in liver increased slightly,and the concentrations of MDA and H2O2 showed a decreasing trend.While the mRNA expression of HO-1 and NQO1 enhanced in liver tissues decreased.In summary,PNP decreased activities of antioxidases in liver of rats,increased the lipid peroxidation in liver tissues,which furtherly resulted in oxidative stress in liver.Supplementation with Arg could enhance the activity of antioxidase,reduced the formation of lipid peroxidation products,thus alleviated the lipid peroxidation in PNP-exposed rats.2.The protective effects of arginine against ovarian damage in PNP-exposed premature ratsThis experiment is aimed to investigate ameliorative effects of Arg on ovarian damage of PNP-exposed premature rats.The experiment was arranged as a 2×2 factorial design,including diet type(0 g/kg Arg or 13 g/kg Arg)and PNP injection(100 mg/kg b.w.or the same dose of PBS).A total of 24 female SD rats aged 3 weeks were chosen and divided into 4 groups:CT group(Control+PBS),CTA group(Arg+PBS),PNP group(Control+PNP),PNPA group(Arg+PNP).Dietary Arg and PNP subcutaneous injection were performed simultaneously,and the experiment lasted for 1 week.After the last treatment,all animals were sacrificed and the serum and ovaries samples were collected.The results showed that compared with CT group,subcutaneous PNP injection(PNP group)decreased ovary weight and its index.The concentraton of 17?-estradiol(E2)significantly accumulated in serum.The quantity of atresic and tertiary follicles raised and decreased significantly,accompanied by the significant increase of percentage of atresic and primordial follicles,and by the significant decreased percentage of tertiary follicles.The total number of follicles reduced significantly in PNP-exposed group.The mRNA expresson levels of Nrf2 and HO-1 in ovarian tissues were also significantly increased.However,compared with PNP group,dietary supplementation of 13 g/kg arginine(PNPA group)decreased the number of arestic follicles significantly,increased the number of tertiary follicles.The percentage of tertiary follicles and primary follicles increased,and the percentage of atresic and primordial follicles decreased slightly.The activities of T-SOD and GSH showed a increased trend,and the concentration of MDA slightly descended in ovary.The expression of of Nrf2 and HO-1 mRNA was subtly attentuated in PNPA group.In summary,PNP could affect follicular development in premature rats,and induce oxidative injure as a reproductive toxicant.Dietary Arg could alleviate the PNP-induced ovarian toxicity,and mitigate the oxidative damage of ovary in premature rats.3.The protective effects of arginine against ovarian damage in PNP-exposed sexually matured ratsIn the last chapter,we found that Arg could alleviate ovarian oxidative damage in PNP-exposed premature rats.Therefore,this experiment is aimed to investigate effects of PNP on ovarian function in rats and the protective effect of Arg.The experiment was arranged as a 2×2 factorial design,including diet type(0 g/kg Arg or 13 g/kg Arg)and PNP injection(100 mg/kg b.w.or the same dose of PBS).A total of 32 female SD rats aged 3 weeks were divided into 4 groups:CT group(Control+PBS),fed with control diet.CTA group(Arg+PBS),fed with Arg diet.PNP group(Control+PNP),first 2 weeks fed with control diet,second 2 weeks PNP 100 mg/kg b.w.subcutaneous injection + control diet.PNPA group(Arg+PNP),first 2 weeks fed with Arg diet,second 2 weeks PNP 100 mg/kg b.w.subcutaneous injection + Arg diet).Serum and ovarian tissues were collected at the end of 4 weeks.The results showed that compared with CT group,subcutaneous injected with PNP(PNP group)reduced average daily gain(ADG)in sexually matured rats significantly,also the liver weight and liver index.The concentration of E2 and P4 in serum was decreased.The duration of anestrus was significantly prolonged.The concentration of MDA and H2O2 accumulated significantly in ovary and serum,respectively,while the activities of T-SOD and CAT significantly lowered in ovarian tissues.However,compared with PNP group,dietary supplementation of 13 g/kg arginine(PNPA group)increased slightly the ADG slightly,along with the liver weight and liver index.The concentration of E2 in serum was increased.The duration of anestrus returned to the CT group level.The concentration of MDA decreased in ovary,while the activities of T-SOD and CAT increased significantly.In serum,the levels of MDA and H2O2 still lowered and the activity of CAT enhanced.In summary,the same as prematrue rats,subcutaneous injection PNP could also disturb the normal estrous cycle in sexually mature rats,affect the normal ovarian function and result in ovarian oxidative damage.Dietary Arg could attenuate ovary injure induced by PNP,which might be related to the enhanced antioxidation ability in rats fed with Arg,and the underlying mechanism needs further investigation.