Effects of Cadmium Exposure on Leydig Cells and Blood Vessels in Mouse Testis

Emerging insights into the impacts of heavy metals exposure on health, reproductive and productive performance of livestock

Heavy metals, common environmental pollutants with widespread distribution hazards and several health problems linked to them are distinguished from other toxic compounds by their bioaccumulation in living organisms. They pollute the food chain and threaten the health of animals. Biologically, heavy metals exhibit both beneficial and harmful effects. Certain essential heavy metals such as Co, Mn, Se, Zn, and Mg play crucial roles in vital physiological processes in trace amounts, while others like As, Pb, Hg, Cd, and Cu are widely recognized for their toxic properties. Regardless of their physiological functions, an excess intake of all heavy metals beyond the tolerance limit can lead to toxicity. Animals face exposure to heavy metals through contaminated feed and water, primarily as a result of anthropogenic environmental pollution. After ingestion heavy metals persist in the body for an extended duration and the nature of exposure dictates whether they induce acute or chronic, clinical or subclinical, or subtle toxicities. The toxic effects of metals lead to disruption of cellular homeostasis through the generation of free radicals that develop oxidative stress. In cases of acute heavy metal poisoning, characteristic clinical symptoms may arise, potentially culminating in the death of animals with corresponding necropsy findings. Chronic toxicities manifest as a decline in overall body condition scoring and a decrease in the production potential of animals. Elevated heavy metal levels in consumable animal products raise public health concerns. Timely diagnosis, targeted antidotes, and management strategies can significantly mitigate heavy metal impact on livestock health, productivity, and reproductive performance.

In vivo exposure to electronic waste (e-waste) leachate and hydraulic fracturing fluid adversely impacts the male reproductive system

Human health effects can arise from unregulated manual disassembly of electronic waste (e-waste) and/or hydraulic fracturing fluid spills. There is limited literature on the effects of e-waste and hydraulic fracturing wastewater exposure on the male reproductive system. Thus, this proof-of-concept study begins to address the question of how wastewater from two potentially hazardous environmental processes could affect sperm quality. Therefore, three groups of eight-week-old adult mice were exposed (5 d/wk for 6 wks) via a mealworm (Tenebrio molitor and Zophabas morio) feeding route to either: (1) e-waste leachate (50% dilution) from the Alaba Market (Lagos, Nigeria); (2) West Virginia hydraulic fracturing flowback (HFF) fluid (50% dilution); or, (3) deionized water (control). At 24-hours (hr), 3 weeks (wk), or 9-wk following the 6-wk exposure period, cohorts of mice were necropsied and adverse effects/persistence on the male reproductive system were examined. Ingestion of e-waste leachate or HFF fluid decreased number and concentration of sperm and increased both chromatin damage and numbers of morphological abnormalities in the sperm when compared to control mice. Levels of serum testosterone were reduced post-exposure (3- and 9-wk) in mice exposed to e-waste leachate and HFF when compared to time-matched controls, indicating the long-term persistence of adverse effects, well after the end of exposure. These data suggest that men living around or working in vicinity of either e-waste or hydraulic fracturing could face harmful effects to their reproductive health. From both a human health and economic standpoint, development of prevention and intervention strategies that are culturally relevant and economically sensitive are critically needed to reduce exposure to e-waste and HFF-associated toxic contaminants.

Selenium alleviates cadmium-induced oxidative stress, endoplasmic reticulum stress and programmed necrosis in chicken testes

Cadmium (Cd) is a common heavy metal pollutant, and one of the important target organs of its toxicity is the testis. Selenium (Se) has the ability to antagonize the toxicity of Cd. However, the mechanism of the alleviating effects of Se on Cd in chicken testis injury through oxidative stress, endoplasmic reticulum stress (ERS), and programmed necrosis remained unclear. To explore this, 80 7-day-old chickens were divided into the Control group, the Se group (1.00 mg/kg Se), the Cd group (150.00 mg/kg Cd), and the CdSe group. On the 30th and 60th days, serum and chicken testis tissue samples were collected for testing. The results showed that Cd exposure resulted in swelling and deformation of seminiferous tubules, and thinning of the seminiferous epithelium. The ROS and MDA increased, and the SOD, CAT, GSH, GSH-Px decreased. The expression of GRP78, PERK, IRE1, ATF6, CHOP, and JNK in the Cd group increased. The expression of TNF-α, TNFR1, RIP1, RIP3, MLKL, and PARP1 increased, while the expression of Caspase-8 decreased. Histopathological changes, oxidative stress, ERS, and programmed necrosis were improved after CdSe treatment. In conclusion, Se antagonized the toxicity of Cd, and Se could alleviate Cd-induced oxidative stress, ERS, and programmed necrosis in chicken testis.

Nano-selenium Alleviates Cadmium-Induced Mouse Leydig Cell Injury, via the Inhibition of Reactive Oxygen Species and the Restoration of Autophagic Flux

Cadmium (Cd) is a well-known environmental pollutant that can contribute to male reproductive toxicity through oxidative stress. Nano-selenium (Nano-se) is an active single body of selenium with strong antioxidant properties and low toxicity. Some studies have addressed the potential ameliorative effect of Nano-se against Cd-induced testicular toxicity; however, the underlying mechanisms remain to be investigated. This study aimed to explore the protective effect of Nano-se on Cd-induced mouse testicular TM3 cell toxicity by regulating autophagy process. We showed that cadmium exposure to TM3 cells inhibited cell viability and elevated the level of reactive oxygen species (ROS) generation. Morphology observation by transmission electron microscope and the presence of mRFP-GFP-LC3 fluorescence puncta demonstrated that cadmium increased autophagosome formation and accumulation in TM3 cells, resulting in blocking the autophagic flux of TM3 cells. Meanwhile, cadmium remarkably increased the ratio of LC3-II to LC3-I protein expression (2.07 ± 0.31) and the Beclin-1 protein expression (1.97 ± 0.40) in TM3 cells (P < 0.01). Pretreatment with Nano-se significantly reduced Cd-induced TM3 cell toxicity (P < 0.01). Furthermore, Nano-se treatment reversed Cd-induced ROS production and autophagosome accumulation, and autophagy as evidenced by the ratio of LC3-II to LC3-I and Beclin-1 expression. In addition, ROS scavenger, N-acetyl-L-cysteine (NAC) or autophagy inhibitor, 3-methyladenine (3-MA) reversed cadmium-induced ROS generation, autophagosome accumulation, and autophagy-related protein expression levels, which confirmed that cadmium induced TM3 cell injury via ROS signal pathway and blockage of autophagic flux. Collectively, our results reveal that Nano-se attenuates Cd-induced TM3 cell toxicity through the inhibition of ROS production and the amelioration of autophagy disruption.