Inhibition of p38MAPK signal pathway alleviates radiation-induced testicular damage through improving spermatogenesis.

BACKGROUND AND PURPOSE: How to prevent the damage of ionizing radiation to testis has become an urgent problem to be solved. The present aim is to investigate whether inhibition of p38MAPK signaling can alleviate radiation-induced testicular damage.

EXPERIMENTAL APPROACHES: HE staining was used to measure the morphological changes of epididymis and testis after irradiation. Immunohistochemistry staining was used to assess the expression of PLZF, SOX9, p-p38MAPK in testis. Immunofluorescent staining was used to measure the expression of DDX4 and SCP3 in testis. RNA-Seq was used to profile gene expression in testis after irradiation. The expression of Mapk14, Atf2, Ddit3 and Ap1m1 genes was detected by qPCR. Western blotting was used to detect the protein expression of p38MAPK and p-p38MAPK in testis.

KEY RESULTS: There was a dose-response relationship between testicular injury and ionizing radiation. The sperm quality was significantly decreased at 6 and 8 weeks after 6Gy of x-ray radiation. Radiation led to the decrease of PLZF+ cells and increase of SOX9+ cells in testis. There were 969 differential expressing genes in irradiated testis when compared to non-irradiated ones through RNA-Seq. The expression of genes related to p38MAPK signal pathway enriched by GO analysis was significantly increased in irradiated testis, which were further confirmed by qPCR. The protein expression of p-p38MAPK in testis was significantly increased at 28 days after irradiation. SB203580 treatment increased numbers of spermatozoa, the area and diameter of seminiferous tubules and numbers of SOX9+ cells in irradiated mice, which were consistent with the increased sperm movement rate and density under radiation with SB203580 administration. Furthermore, SB203580 treatment significantly increased numbers of SCP3+ cells in testis after irradiation, accelerating the process of spermatogenesis.

CONCLUSIONS AND IMPLICATIONS: Ionizing radiation significantly changes testicular gene expression, in which p38MAPK signaling pathway was activated. Inhibition of p38MAPK signaling by SB203580 partially alleviated the testicular damage caused by radiation and accelerated the recovery of sperms through promoting spermatogenesis.