Effect Of Varicocele On Expression Of HIF-1A,VEGF And Bax In Germ Cells Of Adolescent Rats

Objective:To study the effect of varicocele(VC) on Expression of hypoxia-inducible factor-1[alpha] (HIF-1α),vascular endothelial growth factor (VEGF) and apoptosis associated gene Bax in germ cells of adolescent rats, and investigate the mechanism of the infertility resulting from varicocele.Background:Varicoceles have long been recognized as a cause of male infertility. It is estimated that approximately a third of the men evaluated for infertility have this condition, but not all men with varicocele have abnormal semen parameters. The question of why approximately 15% to 20% of men with varicocele are infertile ,whereas the rest are not infertile remains unanswered. The reason probably lies in the pathophysiology of varicocele, although this is still unclear and requires more in-depth study. Over the years researchers have proposed a number of theories for the mechanisms by which varicocele may impair male infertility. They include hypoxia and most recently apoptosis , but to hypoxia, the proof was not clear on before. HIF-1αis a putative marker of hypoxia and we use an experimental model of varicocele to investigate how varicocele affects HIF-1αexpression ,VEGF expression and Bax expression in the rat testis. Based on these findings we studied whether tissue hypoxia and related pathophysiological events such as angiogenesis and apoptosis occur in varicocele. The aim was to gain new insight into the pathophysiological mechanisms of varicocele related male infertility.Methods:1. Technique of experimental varicocele :The varicocele model was created by partial ligation of the left renal vein in adolescent male Wistar rats, a total of 48 rats (7 weeks,180-220g)were randomly divided into six groups,namely varicocele group(VG), sham operation group(SOG) ,each group of varicocele groups and sham operation groups were 8 rats. varicocele group rats underwent surgery(The left renal vein was tied)in which varicocele was produced,sham surgery group underwent the same operation except ligatures were only placed in position and not tied.2.Immunohistochemistry for HIF-1α, VEGF and Bax:At 30 days and 60 days ,9 0days were completed,the testes were weighed with electronic balance,fixed in Bouin's solution and embedded in paraffin. Histological sections of the left testis of each animal were prepared and stained with hematoxylin and eosin for histopathological examination and performed the expression of HIF-1α,VEGF and Bax were detected by immunohistochemical method. Optical density was detected as index to positive expression.Results:1.Stained with hematoxylin and eosin :Left testis sections from sham operation group showed no significant histological abnormalities. Specimens from varicocele group showed more germ cell desquamation, more congestion and more edema than specimens from sham operation group. These findings were focal in some areas and diffuse in others but focal changes were most prevalent. Some VG specimens also showed less spermatogenesis than specimens from SOG .2.The weight of the left testicular in each VG was lower than that in each SOG (P<0.05). There was significant difference in VG(P<0.05). With the duration of varicocele mode1, The weight of the left testicular in VG was decreased. The left spermatic vein diameter in VG was more phlebectasia than SOG(P<0.01) , There was indistinct difference between SOG (P>0.05), but that was significant difference in VG(P<0.05). With the duration of varicocele mode1,expand degree made more serious.3.Immunohistochemistry for HIF-1α: HIF-1αexpression was detected in germ cell cytoplasm cytoplasm, obviously spermatocyte,and was detected in nucleus of seminiferous tubule theca cell too. There was significant difference in every VG(P<0.01). There was indistinct difference between SOG (P>0.05). Separately the VG and the SOG in 30 days, 60 days, 90 days expression make the parallel comparison, that of 30 days and 60 days group existence obvious difference (P<0.01), 90 days group was indistinct difference (P>0.05).4.Immunohistochemistry for VEGF:VEGF expression was detected in germ cell cytoplasm cytoplasm. There was significant difference in every VG(P<0.01). There was indistinct difference between SOG (P>0.05). Separately the VG and the SOG groups in 30 days, 60 days, 90 days expression make the parallel comparison,that of 30 days and 90 days group existence obvious difference(P<0.05) ,60 days group was indistinct difference (P>0.05).5.Immunohistochemistry for Bax: Bax expression was detected in germ cell cytoplasm cytoplasm and nucleus of seminiferous tubule theca cell, obviously spermatocyte. There was significant difference between VG(P<0.05). There was indistinct difference between SOG (P>0.05) , but Separately the VG and the SOG groups in 30 days, 60 days, 90 days expression make the parallel comparison,there was significant difference(P<0.01).Conclusion: 1. This study reveals that experimental varicocele in the rat is associated with HIF-1αexpression,and support the hypothesis that testicular hypoxia.2. With the duration of varicocele model,HIF-1αand VEGF expression in experiment group was decreased , positive correlation was found between them.It suggest their function was protective in VC mechanism.3. The expression of Bax in left testes of varicocele group is significantly higher than of sham operation group. With the duration of varicocele mode1 , Bax expression in experiment group was increaseed, It suggest VC could promote apoptosis . At the same time , negative correlation was found between HIF-1αand Bax , It suggest HIF-1αcould inhibit apoptosis.