Abstract:

Objective：To investigate whether chemokine like factor (CKLF)-like myelin and lymphocyte and related proteins for vesicle trafficking and membrane link (MARVEL) transmembrane domain-containing protein 2 (CMTM2) is involved in spermatogenesis in varicocele induced sub-fertility rats and  to  discuss the possible mechanisms. Methods: Forty male SD rats (body weight: 220-330 g, age: 6-7 weeks) were randomly divided into 4 groups: varicocele for 4 weeks, varicocele for 12 weeks, sham operation for 4 weeks and sham operation for 12 weeks, with 10 rats in each group. These rats were introduced by partially ligating left kidney veins for the experimental groups, and the sham surgery groups as controls were executed with exactly the same surgery as in the experimental groups except for the ligation. The rats in control and experimental groups for 4 and 12 weeks were killed after laparotomy at the end of 4 and 12 weeks, respectively, the left testes and epididymis were taken out for counting the sperm, observing the seminiferous tubule change and immunochemistry for CMTM2. The changes included sperm density and motility, the outer diameter and inner diameter change and the changes of epithelium and the CMTM2 expression in immunochemistry. Results: Compared with the control groups, the sperm density［（63.9±7.1）×106/mL vs.（74.3±5.0）×106/mL］ and motility［（58.7%±7.9%） vs.（66.1%±4.3%）］ were reduced slightly in group of varicoele for 4 weeks, respectively (t=1.432, 1.563; P=0.076, 0.059, respectively). Varicocele significantly caused a decrease in sperm concentration ［（40.5±7.2）×106/mL vs.（71.1±4.5）×106/mL］ and motility ［（35.2%±8.5%）vs. (63.4%±4.1%)］ at 12 weeks, compared with the related sham groups (t=3.754, 3.933; P=0.004, 0.002, respectively). Additionally, testis CMTM2 exhibited the same disparity, that is, the CMTM2 protein expression in varicocele group was significantly reduced, with the ratio of sham group to varicocele group at the end of 12 weeks 2.3±0.4 (t=1.978; P=0.039). In the evaluation of seminiferous tubules diameter, the external ［(198.2±10.2) μm vs. (255.8±12.7) μm, t=2.125, P=0.003］ and epithelium diameter ［(54.1±1.5) μm vs. (75.5±4.1) μm, t=2.246, P=0.021］ were decreased compared with the sham-related groups and previous varicocele groups. In all the varicocele groups, all types of sperm motility decreased compared with the related sham-operated group (P<0.05). Conclusion: This study suggests varicocele has a detrimental effect on CMTM2 levels and decreases spermatogonia cell number, seminiferous tubules diameter, and sperm indices. CMTM2 is associated with sperm changes in rats with varicocele, and further studies are needed to study the mechanism.

Key words: Chemokine like factor, Spermatogenesis, Varicocele