Comparation Of Different Drug-induced Rat Models Of Cryptorchidism And T3 Regulate NCAM Expression In Flutamid-induced Experimental Cryptorchidism Treated By T3

Objectives:To establish rat models of cryptorchidism in-utero exposing to dibutyl phthalate (DBP),diethylstilbestrol (DES),Flutamide (Flu), and compare pathological difference. Explore the effect of T3 regulate the development of Gonocyte (Go) and the expression of NCAM in the Flu-induced cryptorchidism SD rats.Methods:①Pregnant SD rats were treated DES,Flu by subcutaneous injections and DBP by intragastric administration from gestational day (GD) 12 to 21 to establish cryptorchidism.50 testis biopsies of clinical cryptorchidism were collected.②The expression of NCAM in the testes were detected by Immunohistochemistry and real RT-PCR.③Postnatal day (PD) 1 and PD20 cryptorchidism SD rat induced by Flu were treated T3 15μg·kg-1·d-1 by subcutaneous injections. Incidence of the cryptorchidism,histology and the expression of NCAM were included in the research.Results:①The testes of Flu-induced located in the groin, and the incidence of cryptorchidism and hypospadias were 42.2% and 93.3% respectively. The volume and organ coefficient of the testes were significant lower than that of the normal (P<0.01). Lumen of seminiferous tubules in the Flu-induced cryptorchidism were delayed to be present. Gonocyte remained in the center of cryptorchidism seminiferous tubules on PD20 and PD80, and no spermatozoas could be seen on PD80. There was significant difference in mean seminiferous tubular diameters (MSTD) and area (MSTA) compared to the normal (P<0.01).②The incidence of cryptorchidism in DBP-induced rat and hypospadias were 42.5% and 25.0% respectively. Testes of the cryptorchidism were located in the abdominal cavity, and no spermatozoas could be seen in the seminiferous tubules. The volume and organ coefficient were significant lower than that of the normal (P<0.01). There were few spermatogenic cells and no spermatozoas could be seen in the seminiferous tubules, and only a few Sertoli cells found in some tubules.③High dose of DES would lead the pregnant rat to abortion or death, while DES 1.5μg·kg-1·d-1 could not induce cryptorchidism. There was no significant difference between DES induced testis and the normal in the volume,organ coefficient,MSTD and MSTA of the testes (P>0.05). Abundant of spermatozoas could be seen in the tubules.④There were 4 types of the NCAM expression in the 50 biopsies testis from human cryptochidism. (1) 42% of them NCAM negative expression in seminiferous tubules but positive in interstitial cells, which were physiological expression during maturation; (2) 26% of them NCAM positive expression in seminiferous tubules and in interstitial cells; (3) 28% of them NCAM positive expression in seminiferous tubules and negative in interstitial cells; (4) 4% of them NCAM negative expression in seminiferous tubules and in interstitial cells.⑤The expression of NCAM in the DES, DBP and normal group were similar. It could be seen positive expression on the Gonocyte membrane in the PD1 seminiferous tubules. Gonocyte already migrated to the basement membrane on PD10, and the expression of NCAM became weak or even disappear. NCAM negatively expressed in PD20 and PD80 cryptorchidism seminiferous tubules. NCAM positively expressed in Flu-induced cryptorchidism seminiferous tubules on PD10, PD20 and PD80. After Flu-induced offsprings treated by T3 15μg·kg-1·d-1, NCAM negatively expressed in seminiferous tubules of cryptorchidism.⑥The incidence of cryptorchidism in the group of Flu-induced offsprings treated by T3 15μg·kg-1·d-1 from PD1 was 25% (4/16), which was lower than that of Flu group. And T3 maybe contribute to the presence of lumen and down-regulate NCAM expression in Flu-induced cryptorchidism.⑦NCAM mRNA expression in Flu-induced testes on PD13 was up-regulate than that of the control (P<0.05). NCAM mRNA expression in Flu-induced testes treated by T3 15μg·kg-1·d-1 was significant down-regulate than that without T3 (P<0.05), and there was no significant difference compare with the normal testes (P>0.05).Conclusions:①Among the experimental cryptorchidism models induced by DES, DBP and Flu in-utero exposure, only in Flu-induced testes can be found the NCAM positive expression and remained Gonocyte in the center of seminiferous tubules, which adapte to research the maldevelopment of the Gonocyte in clinical cryptorchidism.②The incidence of Flu-induced cryptorchidism can be decreased by T3 after birth. T3 may contribute to the presence of lumen and down regulate the expression of NCAM, and reduce or eliminate the remainded Gonocytes in crytorcidism seminiferous tubules.