Combination Effect Of Zearalenone And Soybean Isoflavone On The Development Of Reproductive Organs, Liver Damage And Tissues Residue Of Zearalenone In Prepubertal Gilts

The aim of the present research was to determine the interactive effect of zearalenone (ZEA) and soybean isoflavone (ISO) on the development of reproductive organs and reproductive hormones, and explore its potential mechanism of interaction in prepubertal gilts. Additionally, the interactive effects of ZEA and ISO on the liver function, serum parameters, residue of ZEA in liver and muscle and growth performance also were investigated.Ninety 75-day-old female pigs (Duroc×Landrace×Yorkshire,26.50±0.60 kg) were randomly allocated to nine diet treatments during the 21 day study. The experiment employed a 3×3 factorial design using a non-soybean meal diet with addition of 0,0.5 or 2.0 mg/kg ZEA and 0,300 or 600 mg/kg ISO. The main results were showed as fellow.1. Effect of ZEA and ISO on the development of reproductive organs and reproductive hormones in prepubertal gilts. The results indicated that diets supplemented with 2 mg/kg ZEA could increase weight of the reproductive organs and width of vulvas (P<0.05). ISO could enhance the increased weight of the reproductive organs and the width of vulva induced by ZEA with 0.5 mg/kg in diets. However, ISO with 300-600 mg/kg in diets could reduce the increased weight of reproductive organs and edema of vulva induced by ZEA with 2 mg/kg in diets of prepubertal gilts (P<0.05). Analysis of RT-PCR and Western blot analysis indicated that ZEA with 2 mg/kg in diets increased the expression of ERa and reduced the expression of ERβin uterus and vagina (P<0.05). Simultaneous provision of ISO and 2 mg/kg ZEA to prepubertal gilts reduced the expression of ERa, and increased the expression of ERβin uterus and vagina compared with the pigs offered the diets containing 2 mg/kg ZEA alone (P<0.05). Simultaneous provision of ZEA and ISO to prepubertal gilts increased the level of E2 at days 7 and 14, but decreased it at day 21 (P<0.05). Pigs simultaneously fed 2 mg/kg ZEA and 600 mg/kg ISO had the highest level of FSH (P<0.05). There was a significant interaction (P<0.05) between ZEA and ISO supplementation on the level of LH, and pigs offered diets with 2 mg/kg ZEA and 600 mg/kg ISO had the lowest level of LH on days 14 and 21. RT-PCR and Western blot analysis demonstrated that simultaneous provision of ZEA and ISO to prepubertal gilts upregulated the mRNA expression of ERs in hypothalamus and GnRH receptor in pituitary gland (P<0.05). It appears that ISO can counteract the estrogenic influence of a high dosage of ZEA (2 mg/kg). This affect might be attributed to competitive binding with estrogen receptors in reproductive organs, thereby weakening the estrogenic effect of ZEA. Meanwhile, interactions between ZEA and ISO may interfere with the functioning of E2, FSH and LH and then influence the development of reproductive organs in prepubertal gilts.2. Interaction of ZEA and ISO in diet on the liver function and oxidative damage in prepubertal gilts. The results indicated that diets supplemented with 2 mg/kg ZEA could cause swelling and degeneration of liver cells and lobular stromal hyperplasia in liver of prepubertal. ISO could relieve the pathological changes of liver induced by ZEA with 2 mg/kg in diet. Simultaneous addition of ZEA and ISO to prepubertal gilts increased the level of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) in the serum (P<0.05) at day 14 but their levels decreased (P<0.05) over time. The levels of total protein (TP) and globulin (Glob) in serum increased (P<0.05) over time, and simultaneous addition of ZEA and ISO to prepubertal gilts increased the level of albumin (ALB) at day 21 compared with pigs fed a diet of ZEA alone. There were no significant interactions (P>0.05) between ZEA and ISO supplementation on the levels of IgG and IgM in prepubertal gilts. ZEA increased the level of malondialdehyde (MDA), and decreased the concentrations of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) (P<0.05) in the serum. ISO could relieve the oxidative stress induced by ZEA. The results suggested that ISO added to diets at 600 mg/kg could relieve the liver damage and oxidative stress induced by ZEA added at 2 mg/kg during the growth phase in prepubertal gilts.3. Interaction of ZEA and ISO in diet on the residue of ZEA in the muscle and liver of prepubertal gilts. The results showed that the diet with the addition of ZEA increased (P<0.05) the residue of ZEA in muscle and liver of prepubertal gilts. Simultaneous addition of ZEA and ISO to prepubertal gilts decreased (P<0.05) the content of ZEA in muscle and liver compared with pigs fed a diet with ZEA alone. The residue of ZEA in the liver of pigs fed the diet with 0.5 or 2 mg/kg ZEA reached 291.14 ng/kg and 1352.06 ng/kg, respectively, compared with the value in the control group of 26.31 ng/kg. The content of ZEA in the muscle of pigs fed the diet with 0.5 or 2 mg/kg ZEA reached 9.71 ng/kg and 31.30 ng/kg, respectively, compared with the value in the control group of 8.51 ng/kg. Diets that contained both ZEA and ISO decreased the concentration of ZEA in liver and muscle compared with the addition of ZEA alone. RT-PCR analysis demonstrated that both ZEA and ISO could increase the mRNA expression of 3α/3β-HSD in the liver (P>0.05). Addition of ZEA to prepubertal gilts increased the protein expression of 3α/3β-HSD (P<0.05), and addition of ISO had no significant effect on the protein expression of 3α/3β-HSD (P<0.05). There was a significant interaction (P<0.05) between ZEA and ISO supplementation on the expression of 3α-HSD and 3β-HSD protein in liver of prepubertal gilts. The current study indicated that ISO could reduce the residue of ZEA in liver and muscle. Pigs fed a diet containing ISO may show acceleration of the biotransformation and degradation of ZEA and its metabolites, and this may reduce the residue of ZEA in liver and muscle.4. Interaction of ZEA and ISO in diet on the growth performance and development of other organs in prepubertal gilts. The results indicated that simultaneous addition of ZEA and ISO had no significant influence on average daily gain (ADG), average daily feed intake (ADFI) and feed conversion ratio (FCR) in prepubertal gilts (P>0.05). Addition of ZEA to prepubertal gilts reduced the level of T3 (P<0.05) and had no significant influence on the concentration of GH and T4 (P>0.05) in serum. Supplement of ISO to prepubertal gilts increased the concentration of GH and T3 (P<0.05). Additionally, simultaneous addition of ZEA and ISO to prepubertal gilts had no obvious effects on the relative weight of the heart, liver, lung, kidney and spleen (P>0.05). The current study suggested that simultaneous addition of ZEA with 0.5-2 mg/kg and ISO with 300-600 mg/kg to prepubertal gilts had no obvious effects on the growth performance and organ development during 21-day trial.In conclusion, the estrogenic effect of ZEA would be reinforced when coexistence of ISO and low dosage of ZEA (0.5mg/kg) in the diets. While ISO could offset the estrogenic effect of ZEA when the diets containing the high dosage of ZEA (2mg/kg). The effects of ZEA and ISO on the development of reproductive organs in prepubertal gilts were mediated through interfer the function of reproductive hormones and changing the mRNA transcription of ERs in the reproductive organs. Also, ISO in diet could relieve liver damage and oxidative stress induced by ZEA. ISO could reduce the residue of ZEA in liver and muscle. Additionally, simultaneous addition of ZEA with 0.5-2 mg/kg and ISO with 300-600 mg/kg to prepubertal gilts had no obvious effects on the growth performance during 21-day trial.