Differential Effects of Low and High Radiation Dose Rates on Mouse Spermatogenesis

Abstract

The adverse effects of radiation are proportional to the total dose and dose rate. We aimed to investigate the effects of radiation dose rate on different organs in mice. The mice were subjected to low dose rate (LDR, ~3.4 mGy/h) and high dose rate (HDR, ~51 Gy/h) radiation. LDR radiation caused severe tissue toxicity, as observed in the histological analysis of testis. It adversely influenced sperm production, including sperm count and motility, and induced greater sperm abnormalities. The expression of markers of early stage spermatogonial stem cells, such as Plzf, c-Kit, and Oct4, decreased significantly after LDR irradiation, compared to that following exposure of HDR radiation, in qPCR analysis. The compositional ratios of all stages of spermatogonia and meiotic cells, except round spermatid, were considerably reduced by LDR in FACS analysis. Therefore, LDR radiation caused more adverse testicular damage than that by HDR radiation, contrary to the response observed in other organs. Therefore, the dose rate of radiation may have differential effects, depending on the organ; it is necessary to evaluate the effect of radiation in terms of radiation dose, dose rate, organ type, and other conditions.

A Brief Overview of Radiation-Induced Effects on Spermatogenesis and Oncofertility

“…Furthermore, based on data revealed in recent studies, these thresholds appear to be significantly affected by the radiation dose rate. One previous study has demonstrated that LDR radiation leads to more adverse testicular damage than that following high-dose-rate (HDR) radiation, in contrast to the observed responses of other organs [21]. Research suggests that the DNA damage to spermatogonia cells and other cells during meiosis that is induced by chronic LDR irradiation may not be repaired efficiently, and the accumulating mutations may result in enhanced cell death when compared to damage induced by HDR radiation.…”

“…Research suggests that the DNA damage to spermatogonia cells and other cells during meiosis that is induced by chronic LDR irradiation may not be repaired efficiently, and the accumulating mutations may result in enhanced cell death when compared to damage induced by HDR radiation. Nevertheless, the underlying mechanisms of this process remain to be determined [21]. This characteristic, known as the 'inverse dose-rate effect', is another important radiation-induced impact on spermatogenesis.…”

Ultrastructural Analysis of Large Japanese Field Mouse (Apodemus speciosus) Testes Exposed to Low-Dose-Rate (LDR) Radiation after the Fukushima Nuclear Power Plant Accident

“…This small mammal is common in Japan, it shows seasonal changes in seminiferous tubule morphology due to its breeding season and serves as a reference animal for the surrounding ecosystem [12,13]. Its reproductive function can be affected by physical and chemical changes as the testis is one of the most known radiosensitive organs, consisting of germ cells at different developmental stages of the spermatogenic cycle [14][15][16][17][18]. The susceptibility to radiation exposure differs between spermatogonia and spermatocytes, according to spermatogenic stages [19,20].…”

Treatment progress of cryptozoospermia with Western Medicine and traditional Chinese medicine: A literature review

“…At present, all factors causing decreased spermatogenesis may be the mechanism of cryptozoospermia, such as chromosomal abnormalities, 5 genetics, 6 urogenital system congenital anomalies, 7 infection, 8 immune damage, 9 testicular microlithiasis, 10 hydrocele, 11 varicocele, 12 abnormal sex hormones, 13 toxins, 14 radiation, 15 and tumors. 16 …”

“…At present, all factors causing decreased spermatogenesis may be the mechanism of cryptozoospermia, such as chromosomal abnormalities, 5 genetics, 6 urogenital system congenital anomalies, 7 infection, 8 immune damage, 9 testicular microlithiasis, 10 hydrocele, 11 varicocele, 12 abnormal sex hormones, 13 toxins, 14 radiation, 15 and tumors. 16 With the development of cryotherapy, biological treatment, drugs, surgery, assisted reproductive technology (ART), and traditional Chinese medicine (TCM), an increasing number of studies or case reports of new methods have obtained good results; however, there is no consensus, and more uncertainties need to be discussed.…”