Decreased vascular contraction and changes in oxidative state in middle–aged Wistar rats after exposure to increased levels of dietary zinc

Both copper and zinc are known to be important for maintaining health, but most research has focused on deficiencies of these elements. Recent studies have shown that high levels of Cu can be toxic, especially to the cardiovascular (CV) system. However, little research has been done on the effects o...

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Published in:Toxicology and applied pharmacology 2024-10, Vol.491, p.117049, Article 117049
Main Authors: Borkowska-Sztachańska, Małgorzata, Thoene, Michael, Socha, Katarzyna, Juśkiewicz, Jerzy, Majewski, Michał S.
Format: Article
Language:English
Subjects:
Aged Rats
AH–6809
Dietary Zinc
Heme Oxygenase–1
NS–398
Vascular Studies
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Summary:Both copper and zinc are known to be important for maintaining health, but most research has focused on deficiencies of these elements. Recent studies have shown that high levels of Cu can be toxic, especially to the cardiovascular (CV) system. However, little research has been done on the effects of higher levels of Zn on the CV system. In this study, male Wistar rats aged 12 months were given a diet with twice the recommended daily allowance of zinc (31.8 mg/kg of diet) and compared to a control group (15.9 mg/kg of diet) after 8 weeks. Blood plasma and internal organs of both groups were examined for levels of copper, zinc, selenium and iron, as well as several key enzymes. Aortic rings from both groups were also examined to determine vascular functioning. There were very few changes in the vascular system functioning after chronic exposure to zinc, and only one enzyme, heme oxygenase–1 (HO–1) was elevated, whereas vascular contraction to noradrenaline decreased with no changes in vasodilation to acetylcholine. Of the micronutrients, zinc and selenium were elevated in the blood plasma, while copper decreased. Meanwhile, the total antioxidant status increased. These were not observed in the liver. Therefore, it is proposed that there is a mechanism in place within the vascular system to protect against the overproduction of heme, caused by chronic zinc exposure. •Heme oxygenase–1 increased (1.3–fold) together with increasing dietary Zn in the blood;•Vascular contraction to noradrenaline decreased in Zn supplemented rats;•Vascular relaxation to acetylcholine was not modified;•Zn (1.11–fold), Se (1.13–fold) and TAS (1.77–fold) increased in the blood;•Cu (0.68–fold), and the Cu/Zn (0.63–fold) and Cu/Se (0.61–fold) ratios decreased.
ISSN:0041-008X
1096-0333
1096-0333
DOI:10.1016/j.taap.2024.117049