Ethanol binge drinking during pregnancy and its effects on salivary glands of offspring rats: oxidative stress, morphometric changes and salivary function impairments

Identification and culture of functional salivary gland ductal epithelial cells

Sialadenitis is a prevalent salivary gland disease resulting in decreased salivary flow rate. To date, little is known about the exact changes and mechanism of ductal cells in sialadenitis. This study aims to establish an efficient method to identify and isolate ductal cells, thereby facilitating further research on this specific cell type. Immunofluorescence for cytokeratin 13 and cytokeratin 19 was conducted in salivary glands to confirm their specificity as ductal cell markers. The dissected ducts were assessed through PCR and Western blot of cytokeratin 19 and digested by dispase and collagenase. The functionality of the isolated ductal cells was determined by measuring intracellular calcium. Cytokeratin 19 and cytokeratin 13 were expressed in all segments of human ducts. Cytokeratin 19 was limited to ducts excluding granular convoluted tubules in rat and mouse. The purities of the obtained ductal cells were approximately 98% in humans and 93% in rats. Furthermore, intracellular free calcium increased with time and concentration of carbachol treatment. Cytokeratin 19 serves as a dependable marker for identifying ductal cells in salivary glands, except for granular convoluted tubules. Moreover, we have successfully developed an efficient method for isolating ductal cells from salivary glands.

Atrophy and Inflammatory Changes in Salivary Glands Induced by Oxidative Stress after Exposure to Drugs and Other Chemical Substances: A Systematic Review

Background and Objectives: Oxidative stress is involved in the alterations at the level of salivary glands, being the cause of oral pathologies like xerostomia, periodontitis, gingivitis, leucoplakia, and cancer. It is known that antioxidants can reverse changes induced by drugs or other chemicals in some organs, but the question is whether these substances can reduce or revert the effects of oxidative stress at the salivary gland level. Our aim was to find histopathological data at the level of salivary glands supporting the hypothesis of the reversal of oxidative stress-induced changes after the treatment with substances with antioxidant effect. Materials and Methods: A systematic search was conducted in PubMed, Science Direct, and Springer databases, including research articles on oxidative stress histological aspects and oxidative stress biomarkers induced by drugs or other chemicals on salivary glands. Results: Out of 1756 articles, 25 articles were selected with data on tissue homogenate used for biochemical analysis of oxidative and antioxidative markers, along with routine hematoxylin eosin (HE) and immunohistochemical analysis used for histopathological and immunohistochemical diagnosis. Drugs (antineoplastic drugs, antibiotics, and analgesics), alcohol, heavy metals, and fluoride can cause oxidative stress, resulting in morphological changes in different tissues, including in salivary glands. There are many antioxidants but only a few were evaluated regarding the effects on salivary glands in animal studies, such as hesperidin and selenium, which can reverse the damage induced by cyclophosphamide; 10-dehydrogingerdione (10-DHGD), a compound extracted from ginger, which has a protective effect against the oxidative stress and apoptosis induced by tramadol; and glycyrrhizic acid, which may repair the injuries incurred after the administration of sodium nitrite. Conclusions: Substances such as hesperidin, selenium, 10-dehydrogingerdione, and glycyrrhizic acid are antioxidants with proven restorative effects on salivary glands for the damage induced by oxidative stress after exposure to drugs and other chemical substances; however, demonstrating their similar effects in human salivary glands is challenging.

Assessment of the toxic effects of levetiracetam on biochemical, functional, and redox parameters of salivary glands in male Wistar rats

Levetiracetam (LEV) is an anticonvulsant for epilepsy. The toxic effects of this medication in tissues have been associated with redox state imbalance, which can lead to salivary gland dysfunction. Therefore, the current work investigated the effects of LEV on the biochemical, functional, and redox parameters of the parotid and submandibular glands in rats. For this, male Wistar rats (Rattus norvegicus albinus) were randomly divided into 3 groups (n = 10/group): Control (0.9% saline solution), LEV100 (100 mg/kg), and LEV300 (300 mg/kg). After 21 consecutive days of intragastric gavage treatments, pilocarpine stimulated saliva secretion was collected for salivary biochemical analysis. The extracted salivary glands were utilized for histomorphometry and redox state analyses. Our results showed that LEV300 increased plasma hepatotoxicity markers and reduced salivary amylase activity and the acinar surface area of the parotid gland. Total oxidant capacity and oxidative damage to lipids and proteins were higher in the parotid gland, while total antioxidant capacity and uric acid levels were reduced in the submandibular gland of the LEV100 group compared to Control. On the other hand, total oxidant capacity, oxidative damage to lipids and proteins, total antioxidant capacity, and uric acid levels were lower in both salivary glands of the LEV300 group compared to Control. Superoxide dismutase and glutathione peroxidase activities were lower in the salivary glands of treated animals compared to Control. In conclusion our data suggest that treatment with LEV represents a potentially toxic agent, that contributes to drug-induced salivary gland dysfunction.

Aerobic Physical Training Attenuates Oxidative Stress in the Spinal Cord of Adult Rats Induced by Binge-like Ethanol Intake

Binge drinking is the most frequent consumption pattern among young adults and remarkably changes the central nervous system; thus, research on strategies to protect it is relevant. This study aimed to investigate the detrimental effects of binge-like EtOH intake on the spinal cord of male rats and the potential neuroprotective effects provided by moderate-intensity aerobic physical training. Male Wistar rats were distributed into the 'control group', 'training group', 'EtOH group', and 'training + EtOH'. The physical training protocol consisted of daily 30-min exercise on a treadmill for 5 consecutive days followed by 2 days off during 4 weeks. After the fifth day of each week, distilled water ('control group' and 'training group') or 3 g/kg of EtOH diluted at 20% w/v ('EtOH group' and 'training + EtOH group') was administered for 3 consecutive days through intragastric gavage to simulate compulsive consumption. Spinal cord samples were collected for oxidative biochemistry and morphometric analyses. The binge-like EtOH intake induced oxidative and tissue damage by decreasing reduced glutathione (GSH) levels, increasing lipid peroxidation (LPO), and reducing motor neurons (MN) density in the cervical segment. Even under EtOH exposure, physical training maintained GSH levels, reduced LPO, and prevented MN reduction at the cervical segment. Physical training is a non-pharmacological strategy to neuroprotect the spinal cord against oxidative damage induced by binge-like EtOH intake.

Physical Exercise Mitigates Salivary Gland and Saliva Damages in Rats Exposed to Binge-like Ethanol Pattern

Heavy episodic ethanol (EtOH) consumption is a typical pattern, especially among younger people. The therapeutic effect of exercise on EtOH damage has not yet been fully elucidated. Therefore, this study aims to investigate whether moderate exercise can reduce the damage generated by ethanol consumption in salivary glands and saliva. Thus, 32 male Wistar rats were divided into four groups: control (sedentary animals treated with water); training (trained animals treated with EtOH); EtOH (sedentary animals treated with EtOH); and EtOH + training (trained animals treated with ethanol). EtOH was administered to the animals at a dose of 3 g/kg/day at a concentration of 20% w/v for three consecutive days per week via intragastric gavage. The training was performed on a treadmill for five successive days. At the end of the 4-week experimental protocol, the animals were euthanized, and salivary glands and saliva were collected for oxidative biochemistry analysis. Our results showed that EtOH consumption generated changes in the oxidative biochemistry of the salivary glands and saliva. Thus, it was possible to conclude that moderate physical exercise can significantly recover antioxidant activity, reducing the damage generated by EtOH.

DNA Damage and Proteomic Profile Changes in Rat Salivary Glands After Chronic Exposure to Inorganic Mercury

Mercury (Hg) is a toxic metal that became a public health problem due to environmental contamination caused by anthropogenic activity. In this sense, oral homeostasis can undergo changes due to the toxic effects of metal on the salivary glands. Therefore, our objective was to investigate the proteomic and genotoxic changes in salivary glands after exposure to inorganic mercury (IHg). Forty Wistar rats that were divided into a control group, which received distilled water, and an exposed group, which received 0.375 mg/kg of mercury chloride for 45 days via orogastric gavage. After that, the animals were euthanized, and the parotid and submandibular glands were collected for analysis of the genotoxic effects, using the comet assay and proteome global profile assessment. The results showed that IHg promoted damage to cellular DNA associated with proteomic changes that showed events such as oxidative stress, mitochondrial dysfunction, changes in the cytoskeleton, and apoptosis. Therefore, these findings show a profile of molecular changes due to the interactions of IHg with several proteins and mechanisms inherent to the cell, which consequently may result in dysfunction of the salivary glands and impaired homeostasis of the oral cavity.

Maternal Fluoride Exposure Exerts Different Toxicity Patterns in Parotid and Submandibular Glands of Offspring Rats

There is currently a controversial and heated debate about the safety and ethical aspects of fluoride (F) used for human consumption. Thus, this study assessed the effects of prenatal and postnatal F exposure of rats on the salivary glands of their offspring. Pregnant rats were exposed to 0, 10, or 50 mg F/L from the drinking water, from the first day of gestation until offspring weaning (42 days). The offspring rats were euthanized for the collection of the parotid (PA) and submandibular (SM) glands, to assess the oxidative biochemistry and to perform morphometric and immunohistochemical analyses. F exposure was associated with a decrease in the antioxidant competence of PA in the 10 mg F/L group, contrasting with the increase observed in the 50 mg F/L group. On the other hand, the antioxidant competence of the SM glands was decreased at both concentrations. Moreover, both 10 and 50 mg F/L groups showed lower anti-α-smooth muscle actin immunostaining area in SM, while exposure to 50 mg F/L was associated with changes in gland morphometry by increasing the duct area in both glands. These findings demonstrate a greater susceptibility of the SM glands of the offspring to F at high concentration in comparison to PA, reinforcing the need to adhere to the optimum F levels recommended by the regulatory agencies. Such findings must be interpreted with caution, especially considering their translational meaning.

The effect of long-term alcohol intoxication on the morphological structures and enzymatic activity of rat salivary glands

BACKGROUND

To study changes in the morphological structures and enzymatic activity of the submandibular salivary gland (SMG) and parotid salivary gland (PG) in rats after prolonged alcohol intoxication.

METHODS

Sexually mature male Wistar rats consumed 20% ethanol (6.9 g/kg/day) for 180 consecutive days. The PG and SMG were collected for morphometric and histochemical analyses (nonparametric Mann-Whitney U test, p < 0.05).

RESULTS

After exposure to ethanol for 180 days, the PG showed a change in the shape of the acini and the secretory cells that formed them, uneven expansion of the interlobular excretory ducts, and moderate fatty infiltration in the stroma. After exposure to ethanol for 180 days, the SMG showed fatty infiltration and stromal edema, and changes in acinar cells, intercalated ducts, and striated ducts. There was a significant decrease in the relative and absolute weight of the SMG. The number of mast cells in the PG and SMG and their degranulation index increased 2-fold after exposure to ethanol. All mast cells were highly active. After ethanol exposure, the activity of alkaline phosphatase increased significantly in the myoepithelial cells of the SMG and PG; the activity of NADPH oxidase increased only in the acini SMG, and the activity of succinate dehydrogenase remained at the control level in the acini of both glands. In the ducts of these glands, the activity of other enzymes did not change.

CONCLUSIONS

Changes in the morphological structures, morphometric parameters, and enzymatic activity of the rat salivary glands after 180 days of ethanol intoxication are shown for the first time. The most pronounced changes were found in the SMG.

Ethanol- and Cigarette Smoke-Related Alternations in Oral Redox Homeostasis

Alcohol abuse as well as smoking cigarettes has been proven to negatively affect the oral environment. The aim of this work was to provide a systematic review of the literature on the influence of ethanol and cigarette smoking on oral redox homeostasis. A search was performed for scientific articles indexed in the PubMed, Medline and Web of Science databases. We identified 32,300 articles, of which 54 were used for the final review, including the results from 2000 to 2021. Among the publications used to write this article, n = 14 were related to the influence of alcohol consumption (clinical studies n = 6, experimental studies n = 8) and n = 40 were related to the influence of smoking (clinical studies n = 33, experimental studies n = 7) on oral redox homeostasis. The reviewed literature indicates that alcohol abusers and smokers are more likely to suffer from salivary gland dysfunction, as well as develop precancerous lesions due to DNA damage. Compared to alcohol abstainers and non-smokers, alcohol drinkers and smokers are also characterized by a deterioration in periodontal health measured by various indicators of periodontal status. In summary, alcohol abuse and smoking are associated with disrupted oral redox homeostasis, which may lead not only to tooth loss, but also contribute to various adverse effects related to mental health, digestive processes and chronic inflammation throughout the human body.