Department of Medicine and Surgery, University of Perugia, Perugia, Italy.
Division of Medical Andrology and Endocrinology of Reproduction, Saint Mary Hospital, Terni, Italy.
Front Endocrinol (Lausanne). 2023 Feb 10;14:962519. doi: 10.3389/fendo.2023.962519. eCollection 2023.
Among substances released into the environment by anthropogenic activities, the heavy metal cadmium (Cd) is known to induce severe testicular injury causing male subfertility/infertility. Zinc (Zn) is another heavy metal that, unlike Cd, is physiologically present in the testis, being essential for spermatogenesis. We aimed to examine the possibility that 50 µM ZnCl could counteract the toxic effects induced by Cd in an model of porcine prepubertal Sertoli cells (SCs) exposed to both subtoxic (5 μM) and toxic (10 μM) concentrations of CdCl for 48 h.
Apoptosis, cell cycle, and cell functionality were assessed. The gene expression of Nrf2 and its downstream antioxidant enzymes, ERK1/2, and AKT kinase signaling pathways were evaluated.
We found that Zn, in co-treatment with subtoxic and toxic Cd concentration, increased the number of metabolically active SCs compared to Cd exposure alone but restored SC functionality only in co-treatment with subtoxic Cd concentration with respect to subtoxic Cd alone. Exposure of Cd disrupted cell cycle in SCs, and Zn co-treatment was not able to counteract this effect. Cd alone induced SC death through apoptosis and necrosis in a dose-dependent manner, and co-treatment with Zn increased the pro-apoptotic effect of Cd. Subtoxic and toxic Cd exposures activated the Nrf2 signaling pathway by increasing gene expression of Nrf2 and its downstream genes (SOD, HO-1, and GSHPx). Zn co-treatment with subtoxic Cd attenuated upregulation on the Nrf2 system, while with toxic Cd, the effect was more erratic. Studying ERK1/2 and AKT pathways as a target, we found that the phosphorylation ratio of p-ERK1/2 and p-AKT was upregulated by both subtoxic and toxic Cd exposure alone and in co-treatment with Zn.
Our results suggest that Zn could counteract Cd effects by increasing the number of metabolically active SCs, fully or partially restoring their functionality by modulating Nrf2, ERK1/2, and AKT pathways. Our SC model could be useful to study the effects of early Cd exposure on immature testis, evaluating the possible protective effects of Zn.
在人为活动释放到环境中的物质中，重金属镉（Cd）已知会导致严重的睾丸损伤，从而导致男性不育/不孕。锌（Zn）是另一种重金属，与 Cd 不同，它在睾丸中生理存在，对精子发生至关重要。我们旨在研究 50μM ZnCl 是否有可能抵抗在暴露于亚毒性（5μM）和毒性（10μM）浓度 CdCl 48 小时的猪青春期前支持细胞（SCs）模型中由 Cd 诱导的毒性作用。
评估细胞凋亡、细胞周期和细胞功能。评估 Nrf2 及其下游抗氧化酶、ERK1/2 和 AKT 激酶信号通路的基因表达。
我们发现，与单独暴露于 Cd 相比，Zn 在与亚毒性和毒性 Cd 浓度共同处理时增加了代谢活跃的 SC 数量，但仅在与亚毒性 Cd 共同处理时才恢复了 SC 功能，而单独暴露于亚毒性 Cd 时则恢复了 SC 功能。Cd 暴露破坏了 SC 细胞周期，Zn 共同处理不能抵消这种作用。Cd 单独诱导 SC 通过凋亡和坏死死亡，呈剂量依赖性，Zn 共同处理增加了 Cd 的促凋亡作用。亚毒性和毒性 Cd 暴露通过增加 Nrf2 和其下游基因（SOD、HO-1 和 GSHPx）的基因表达激活 Nrf2 信号通路。Zn 与亚毒性 Cd 共同处理减弱了 Nrf2 系统的上调，而与毒性 Cd 共同处理时，效果则更为不稳定。作为一个靶点研究 ERK1/2 和 AKT 途径，我们发现单独和与 Zn 共同处理时，亚毒性和毒性 Cd 暴露均上调了 p-ERK1/2 和 p-AKT 的磷酸化比率。
我们的结果表明，Zn 通过增加代谢活跃的 SC 数量来抵消 Cd 的作用，通过调节 Nrf2、ERK1/2 和 AKT 通路，完全或部分恢复其功能。我们的 SC 模型可用于研究早期 Cd 暴露对未成熟睾丸的影响，评估 Zn 的可能保护作用。
