| Objective Research has indicated that the sexual reproductive development of the human aswell as the animal kingdom has been affected by the ever-increasing environmental estrogens.Testis is the core organ of male reproductive system and its development is regulated by variousgrowth factors. Generally, those factors bring about their effects through their receptors in testis.The mechanism of how environmental estrogens influence the development of testis still remainsunclear at present. What's more, systemic research about the dose-effect relation is seriouslyneeded. Classic environmental diethylstilbestrol (DES) was applied to pregnant female mice inthis experiment. And then the concentrations of the related growth factors and its receptors intesticular tissue were measured during the prepubertal period. Moreover, the mechanism of howdose-effect of the environmental estrogen on the development of testis were explored.Method 200 pregnant female Kungming mice were randomly divided into eight groups:normal group, control group and experimental group 1-6. Those pregnant female mice ofexperimental group 1-6 were given subcutaneous injection of DES during the 9-17 days of thepregnancy. The DES was respectively given with different dosages as: 0.1, 0.5, 10, 25, 50,100μg.kg-1.d-1. The DES, which was used in each group was dissolved in equal amount ofDMSO and normal saline. The control group was given only DMSO and saline while the normalgroup was given nothing. Six newly-born mice were randomly executed after the follow dayscounted after birth as 0, 5, 15 and 25 days. Pathological sections were made out of testicle tissues.Light microscope was used to observe the structural change of testicular tissue.Immunohistochemistrical method was applied respectively to study EGF, EGFR, TGFβ1, TGFβRⅡof the testicular tissue in each group, and their IOD values were determined by specialanalysis software. ANOVA, correlation analysis and regression analysis were adopted to run thestatistics analysis. The values of IOD were expressed as (?)±s.Results 1. The structural influence of DES on the mice testicle tissue: under light microscope,testicle structure of the normal and control group was integrated, convoluted seminiferoustubules were lined up in order with a distinct framework, the seminiferous epithelium cells ofthe tubal wall showed a clear contour and layer. The experimental groups (DES0.1,0.5,10, 25μg.kg-1.d-1) revealed the similar pattem to the normal and control group. The convolutedseminiferous tubule as well as the tubal wall of the experimental groups (DES 50,100μg.kg-1.d-1)became remarkably thin. The cells of the tubal wall aligned out of order. Cell laminating wasvague and had decreased. Lager crevice appeared between cells. Abnormally deciduousspermatocytes were commonly seen in the lumens of the convoluted seminiferous tubule. 2. EGF,EGFR, TGFβ1 and TGFβRⅡwere all expressed in the cytoplasm and cell membrane of thepositive cells. EGF and EGFR mainly accordingly expressed in the Leydig cells 0 day afterbirth; Leydig cells and peritubular cells on the 5th day after birth, Leydig cells and contortedseminiferous tubules on the 15th and 25th day after birth. TGFβ1 and TGFβRⅡmainlyaccordingly expressed in Leydig cells 0 day after birth, Leydig cells and contorted seminiferoustubules on the 5th, 15th and 25th days after birth. 3. The IOD values of EGF and EGFR in testiculartissues in the middle and high dosage of experimental groups (DES 10,50,100μg.kg-1.d-1) werelower than that of normal and control group. And its values decreased along with the increase ofthe DES dosage. The difference showed statistical difference (P＜0.05); The IOD values ofTGFβ1 and TGFβRⅡin testicular tissues were higher than that of normal and control group.The values increased by the DES dosage increased. The increase extent showed statisticaldifference (P＜0.05). 4. The change of IOD values of EGF, EGFR, TGFβ1 and TGFβRⅡin lowdosage experimental groups (DES0.1,0.5μg.kg-1.d-1) were the same as the middle and highdosage experimental groups in certain prepubertal stages, whereas non significant differenceswere found in other stages that compared to the normal and control group (P＞0.05). 5. EGF andEGFR showed strong positive linear correlation (r=0.750, P＜0.01); TGFβ1 and TGFβRⅡalsopresented strong positive linear correlation (r=0.848, P＜0.01); EGF and TGFβ1 shared strongnegative linear correlation (r=-0.842, P＜0.01).Conclusion 1. DES could lead the paramorphia and tissue structural derangement of micetestis and the effects had close relationship with dosage. 2. The locations of EGF, EGFR, TGFβ1 and TGFβRⅡexpression among testicular cells were rather dispersed and unconstant. Theirexpression locations would alter according to the stages of testicular development. 3. DES coulddecrease the contents of EGF and EGFR in mice testis and the effect depends on the dosage.DES could increase the content of TGFβ1 and TGFβRⅡin mice testis and the effect alsodepends on dosage. These results indicate that DES might regulate the testicle development by influencing the expression of related growth factors and their receptors in the testis. 4. Theinfluence of DES on the related growth factors in testis development had the low dose-effectrelation, and it is related to the development time of the testis and also, the DES dosage. 5. EGFand EGFR showed positive dependability as well as TGFβ1 and TGFβRⅡ. These suggest thatEGF might down-regulate its receptors while TGFβ1 could up-regulate its receptors. 6. EGFand TGFβ1 present negative dependability which suggest that they might be a pair ofantagonistic factors in the testicle development process. |
PDF Full Text Request