Protective Effect of Increased Zinc Supply against Oxidative Damage of Sublingual Gland in Chronic Exposure to Cadmium: Experimental Study on Rats

Abstract

Cadmium is one of the main chemical pollutants found in the daily environment of developed countries. Cigarettes are a significant source of that metal, which makes it important in terms of oral cavity health. The aim of this study was to determine if increased supply of zinc in chronic exposure to cadmium might protect the sublingual gland structure against oxidative damage. The experiment took 12 months and was conducted on 72 adult male rats. They were randomized into 9 groups. Eight groups received cadmium in drinking water (as CdCl2) at 5 or 50 mg Cd/dm3 and/or zinc (as ZnCl2) at 30 or 60 mg Zn/dm3. The control group received regular water. In the sublingual gland of all animal groups, levels of oxidative parameters were measured. The oxidative stress index was calculated as a TOS/TAS ratio. Cadmium exposure at 5 mg and 50 mg Cd/dm3 induced oxidative stress in the sublingual glands of the rats. Cadmium reduced the TAS and GSH levels and increased LPO, H2O2, TOS, and OSI. In cadmium exposure conditions, increasing the supply of zinc by 79% or 151%, as compared to the standard dietary intake of this microelement, completely prevented the reduction of TAS and GSH levels and accumulation of LPO, H2O2, and TOS in the examined gland at both exposure levels to that metal. The outcome data confirm the protective effect of increased zinc intake on the sublingual gland tissue in chronic cadmium exposure.

Beneficial Impact of an Extract from the Berries of Aronia melanocarpa L. on the Oxidative-Reductive Status of the Submandibular Gland of Rats Exposed to Cadmium

“…Recent epidemiological studies provide more and more evidence that environmental exposure to this xenobiotic, nowadays occurring in economically developed countries, creates a threat to the health of the general population, mainly including a risk of damage to the kidney, liver, cardiovascular system, and skeleton, as well as the development of cancer and the deterioration of cognitive functions such as hearing and vision [3,9,13,[15][16][17][18]. It has been revealed that numerous effects of toxic action of cadmium, including the damaging impact on the organs of the oral cavity, result from its pro-oxidative properties [5,14,[19][20][21][22][23]. This xenobiotic indirectly mediates the generation of free radicals (FR) and reactive oxygen species (ROS) by weakening the antioxidative barrier (enzymatic and non-enzymatic), induction of the activity of oxidases, and damage to the mitochondria [3,14,21,22].…”

“…Because current environmental exposure to cadmium creates a threat to the health of the general population [3,8,10,11,13,[15][16][17][18] and the lifetime human exposure to this xenobiotic will increase [9][10][11], the attention of researchers in recent years has been focused on finding effective ways to prevent the unfavourable health effects of exposure to this heavy metal. Taking into account the strong pro-oxidative properties of cadmium and the involvement of oxidative stress in the mechanisms of its damaging impact on various organs and systems [3,5,14,[19][20][21][22][23], the greatest interest among the possible protective agents has been paid to natural products characterized by strong antioxidative properties, including polyphenol-rich ones [14,[24][25][26].…”

“…Taking into account the strong antioxidative properties of chokeberries [24,27,28] and pro-oxidative action of cadmium [3,14,19,20], our research team has undertaken a comprehensive study, in the experimental model of low-level and moderate environmental human exposure to this xenobiotic (1 and 5 mg Cd/kg diet, respectively), to investigate whether the administration of an extract from the berries of A. melanocarpa (AME) may protect against this heavy metal toxicity. We have previously reported that the co-administration of 0.1% AME during the treatment with cadmium decreased the accumulation of this element in the body [30] and protected from its damaging impact on the skeleton [21,31] and liver [22,23], as well as improving the body status of zinc and copper [32].…”

“…In the case of the general population's exposure to cadmium, via both diet and tobacco smoke, the oral cavity is the first place of the possible unfavourable action of this element. That is why, taking into account the findings that cadmium, due to the induction of oxidative stress, may have injurious action on the organs of the oral cavity, including the salivary glands [19,20,33], we have recognized it as necessary to estimate whether the administration of AME may also protect from this impact.…”

Zinc Adequacy Is Essential for the Maintenance of Optimal Oral Health

“…Increased zinc has been shown to affect salivary glands. A twelve-month rat study that examined the effect of administering increased levels of zinc on chronic exposure to cadmium, one of the main chemical pollutants in the developed world, found that increased zinc intake had a protective effect on the sublingual gland against oxidative damage with chronic cadmium exposure [53]. However, increased zinc intake should be monitored closely as zinc toxicity has been proven to have a negative effect on the quantity and quality of saliva, probably through changes in neurologic pathways to the salivary glands or effect on the acini cells [54].…”