| Background:Ischemic injury of testis during prepuberty is a common circumstance, such as Fowler-Stephens procedure for high positioned cryptorchidism, Palomo procedure for varicocele, testis torsion and sac neck ligation for inguinal hernia repair, etc. In adult, sexual hormones investigation, semen analysis and gonadal biopsy can be used to evaluate the testicular function. However, these methods are not suitable for the prepubertal testis. Testosterone levels after human chorionic gonadotropin (HCG) stimulation is partially to reflect the function of Leydig cells, but cannot reflect seminiferous tubule compartment. Thus, an objective marker to evaluate the prepubertal testicular function is needed.Inhibin is a heterodimeric glycoprotein, which is composed of a - and β -subunit. Heterodimerization of α-subunit with either form of the β-subunit ( βA and βB) generats dimeric inhibin A and inhibin B, respectively. Inhibin B is the major circulating inhibin in boys. Inhibin B is an important member of the hypothalamo-pituitary-gonadal axis. Inhibin B production is stimulated by FSH and in turn is part of the negative feedback loop regulating FSH secretion in adult. However, whether this inverse correlation between Inhibin B and FSH is occurred or not in prepuberty is still disputed.Purpose:The aim of this study is to investigate whether the inhibin B can reflect the testicular injury by serum inhibin B level, Serum FSH and LH determination, histopathologic examination, and inhibin B beta B-subunit mRNA expression patterns after ischemic injury of the testes in prepubertal rats.Methods:Seventy-two prepubertal male Wister rats were randomly divided into two groups, control group and the right spermatic vessels ligation group, and each group was divided into six subgroups (6 for each). Surgery was conducted when the rats were 25-day-old. In control group, the right spermatic vessels were only dissected. Inspermatic vessels ligation group, the right spermatic vessels were ligated and cut off separately. After operation, 2~3ml blood samples were taken on day 1,3,5,7,9 and 20, respectively, to determine the value of inhibin B (double antibody enzyme-linked immunosorbent assay), FSH and LH; Meanwhile, histological examination and in situ hybridization with beta B-subunit mRNA probes were performed.Result:After the operation, three rats lost. The FSH levels of control group were higher than that of the spermatic vessels ligation group (10.56±1.17 vs 9.02 ± 0.53 mIU/ml, P<0.05 = , but no difference of LH levels between the two groups ( 0.48 ± 0.27 vs 0.45 ± 0.29 mlU/ml, P>0.05). Comparing to the control group (1166.13 ± 10.76 pg/ml) , the inhibin B levels of the spermatic vessels ligation group were significantly decreased (86.97 ± 23.30 pg/ml, p<0.01). No correlation was found between inhibin B and FSH (r=-0.113, P>0.5).Under light microscopy mild testicular atrophy were seen onday 1, and a few germ cells presented apoptosis and necrosis within the seminiferous tubules; There are about 5% seminiferous tubules revealed spermatocytes left from basal membrane; accompany with persist ischemia at the day 5, more than 5% seminiferous tubules exhibited separation of germ cells from basal membrame, and about 5% seminiferous tubules contain no germ cells, which defined as moderate atrophy; Thesevere atrophy presented no germ cells within seminiferous tubule. Interstitial spaces infiltrated by inflammatory cells.Both Sertoli cells and Leydig cells expressed inhibin B beta- B-subunit mRNA. In control group, the strong signals of hybridization were oberserved in Sertoli cell plasma (+++), but weak signals were seen in Leydig cells (+). After the operation, the level of hybridization singal in Sertoli cells reduced at first day (++),at day 3 (+~±), and to almost negative (±) at day 9 . In SCO tubules, the levels of hybridization singal was very weak (±~-).Conclusion:1. No inverse relationship between serum inhibin B and FSH levels in prepubertal Wistar rats.2. Both Sertoli cells and Leydig cells expressed in...
|
PDF Full Text Request