[Peroxiredoxin 4 protects the testis from heat stress]

To explore the protective effect of Peroxiredoxin 4 (PRDX4) on the testes undergoing heat stress in PRDX4 knockout mice.

Twenty-four C57BL/6 mice underwent CRISPR/Cas9-mediated total knockout of the PRDX4 gene and another 24 wild-type mice were used as controls. At 9 weeks of age, the rats were subjected to 15-minute testicular heat stress in 43℃ water once a day for 3 days, or in 25℃ water as the control. Before and at 1 day and 5 weeks after treatment, 4 from each group were sacrificed respectively and their testes harvested for observation of histological changes by HE staining, detection of the apoptosis of spermatogenic cells by TUNEL and determination of the expression of PRDX4 by Western blot and those of the oxidative stress factors hydroxynonenal (HNE) and 8-OHdG by immunohistochemistry.

No statistically significant differences were observed in testicular histology, the apoptosis rate of spermatogenic cells, and the expressions of HNE and 8-OHdG between the PRDX4 knockout mice and wild-type controls (P > 0.05). After 1-day 43℃ heat stress, the PRDX4 knockout mice showed a significantly increased apoptosis rate of spermatogenic cells as compared with the baseline (［38.65 ± 2.57］% vs ［0.46 ± 0.06］%, P < 0.01), and so did the wild-type controls (［13.21 ± 1.43］% vs ［0.33 ± 0.01］%, P < 0.01), higher in the PRDX4 knockout than in the wild-type control group even at 5 weeks after heat stress (［3.09 ± 0.16］% vs ［1.45 ± 0.11］%, P < 0.01). The PRDX4 knockout mice also exhibited a markedly upregulated expression of 8-OHdG (38.25 ± 1.19 vs 19.54 ± 1.13, P < 0.01), and so did the wild-type controls (24.30 ± 1.65 vs 18.22 ± 1.18, P < 0.01), higher in the PRDX4 knockout than in the wild-type control group even at 5 weeks after heat stress (25.40 ± 1.57 vs 23.25 ± 1.48, P < 0.01). The expression of HNE, however, showed no statistically significant difference before and at 1 day after 43℃ heat stress either in the PRDX4 knockout mice or in the wild-type controls (P > 0.05), though remarkably higher in the former than in the latter group at 5 weeks after treatment (28.57 ± 0.56 vs 19.00 ± 1.35, P < 0.01). The expression of 8-OHdG was also higher in the PRDX4 knockout than in the wild-type control group at 5 weeks, but with no statistically significant difference (P > 0.05).

PRDX4 can effectively protect the testis from heat stress and promote the restoration of its spermatogenic function.