Proteomics analysis of intensive exercise-induced disorders of gametogenesis in the testis using isobaric tags for relative and absolute quantification (iTRAQ) analysis

Abstract

In the present study we screened a panel of regulatory proteins associated with gametogenesis disorders in the testis that are induced by intensive exercise. Four-week-old Sprague-Dawley male rats were randomly divided into three groups: a control group, a no-load exercise group and an intensive exercise group. Rats in the control group were free to move in their cage. Rats in the no-load exercise and intensive exercise groups swam for 60 min day−1, six times each week, for a total 9-week exercise regimen; rats in the intensive exercise group swam with a load of 6% body mass. After the last exercise session (or at the end of the 9-week period), a sperm count, reproductive hormone assays, histological analysis of the testis and proteomics analysis were performed for each rat. Mean (± s.d.) sperm concentration was significantly lower in the intensive exercise group than in the control and no-load exercise groups (1.36 ± 0.63 vs 2.12 ± 0.53 and 2.57 ± 0.48 × 106 spermatozoa mL−1 respectively; P < 0.05). Serum testosterone concentrations were also significantly lower in the intensive exercise group (P < 0.01), whereas gonadotrophin-releasing hormone, LH and FSH concentrations were slightly decreased in the intensive exercise group, but not significantly (P > 0.05). Histological analysis showed that the number of spermatogenic cells in the seminiferous tubules was lower in the intensive exercise group than in the control and no-load exercise groups. Proteomics analysis identified 54 proteins that were differentially expressed between the control and intensive exercise groups (31 downregulated, 23 upregulated). Pathway enrichment analysis showed that ribosome and extracellular matrix–receptor interaction pathways play an important role in the signal transduction of testicular gametogenic disorders. Four differentially expressed proteins that were involved in the regulation of reproduction were identified by bioinformatics analysis and validated by targeted mass spectrometry analysis, namely vimentin, collagen α-1(I) chain, fatty acid-binding protein 9 and 40S ribosomal protein S3a. The data suggest that changes in the abundance of differentially expressed proteins after long-term intensive exercise affect the cycle and progression of spermatogenesis, resulting in spermatogenic disorders.