Department of Preventive Medicine, Fujian Provincial Key Laboratory of Environment Factors and Cancer, Key Laboratory of Environment and Health, School of Public Health, Fujian Medical University, Fuzhou, Fujian, China.
Department of Health Law and Policy, School of Public Health, Fujian Medical University, Fuzhou, Fujian, China.
Environ Toxicol. 2024 Nov;39(11):5187-5198. doi: 10.1002/tox.24375. Epub 2024 Aug 9.
The aim of this study was to investigate whether the damage to male offspring induced by cadmium (Cd) exposure during embryonic period leads to the apoptosis of ovarian granulosa cells (OGCs) in the next generation of female offspring, and whether this apoptosis in the offspring was due to paternal genetic effects. Pregnant Sprague-Dawley (SD) rats were exposed to CdCl (0, 0.5, 2.0, or 8.0 mg/kg) by gavage daily for 20 days to produce the filial 1 (F1) generation. F1 males were mated with newly purchased females to produce the F2 generation, and the F3 generation was generated in the same way. No apoptotic bodies were observed in the OGCs of either the F2 or F3 generation as shown by electron microscopy, and a reduced OGC apoptosis rate (detected by flow cytometry) was observed in F2 OGCs from the Cd-exposed group. Moreover, the mRNA (qRT-PCR) levels of Bax and Bcl-2 and the protein (western blotting) level of pro-caspase-8 increased in the F2 generation (p < 0.05). The expression of apoptosis-related miRNAs (qRT-PCR) and methylation of apoptosis-related genes (determined via bisulfite-sequencing PCR) in OGCs were further determined. Compared with those of the controls, the expression patterns of microRNAs (miRNAs) in the F2 offspring were different in the Cd-exposed group. The miR-92a-2-5p expression levels were decreased in both the F2 and F3 generations (p < 0.05), while the average methylation level of apoptosis-related genes did not change significantly (except for individual loci). In summary, this study showed that the paternal genetic intergenerational effect of male Cd exposure during embryonic period induced apoptosis of OGCs in the offspring was weakened, and the transgenerational effect disappeared; nevertheless, intergenerational and transgenerational changes in apoptosis-related genes, epigenetic modifications, DNA methylation, and miRNAs were observed, and may be important for understanding the homeostatic mechanisms of the body to alleviate the intergenerational transmission of Cd-induced damage.
本研究旨在探讨胚胎期镉（Cd）暴露对雄性后代的损伤是否会导致雌性后代下一代的卵巢颗粒细胞（OGC）凋亡，以及这种后代的凋亡是否归因于父系遗传效应。通过灌胃，每天给怀孕的 Sprague-Dawley（SD）大鼠染毒 CdCl2（0、0.5、2.0 或 8.0mg/kg），共 20 天，以产生第一代（F1）后代。F1 雄性与新购买的雌性交配，以产生第二代（F2），并以同样的方式产生第三代（F3）。电镜观察未见 F2 或 F3 代 OGC 中有凋亡小体，流式细胞术检测发现 Cd 暴露组 F2 OGC 的凋亡率降低。此外，F2 代中 Bax 和 Bcl-2 的 mRNA（qRT-PCR）水平和前胱天蛋白酶-8 的蛋白（western blotting）水平升高（p<0.05）。进一步检测了 OGC 中凋亡相关 miRNA（qRT-PCR）的表达和凋亡相关基因的甲基化（通过亚硫酸氢盐测序 PCR 确定）。与对照组相比，Cd 暴露组 F2 后代中 miRNA 的表达模式不同。F2 和 F3 代 miR-92a-2-5p 的表达水平均降低（p<0.05），而凋亡相关基因的平均甲基化水平没有显著变化（除个别位点外）。综上所述，本研究表明，胚胎期雄性 Cd 暴露的父系遗传跨代效应对后代 OGC 凋亡的作用减弱，跨代效应消失；然而，观察到凋亡相关基因、表观遗传修饰、DNA 甲基化和 miRNA 的跨代和代际变化，这可能对于理解机体的动态平衡机制以减轻 Cd 诱导损伤的代际传递具有重要意义。
