Oxidative Modification in the Salivary Glands of High Fat-Diet Induced Insulin Resistant Rats

Expression of glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide in the rat submandibular gland is influenced by pre- and post-natal high-fat diet exposure

Background: Incretins, i.e., glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) promote insulin secretion to reduce postprandial blood sugar. Previous studies found incretins in the salivary glands. However, the role of GLP-1 and GIP in the submandibular gland (SMG) is unclear. This study investigates the effects of a high-fat diet (HFD) on the expression of GLP-1 and GIP throughout the development of rat SMG. Methods: Pregnant 11-week-old Wistar rats were divided into two groups: those fed on a standard diet (n = 5) and those fed on a HFD (n = 5). From day 7 of pregnancy and throughout the lactation period, all the rats were fed on either a chow diet or HFD. The newborns were divided into four subgroups (n = 6): standard diet males (SM), HFD males (HM), standard diet females (SF), and HFD females (HF). The SMGs of 3- and 10-week-old rats from each subgroup were collected under general anesthesia. Moreover, body weight, food intake, and fasting blood sugar were measured. The mRNA expression of GLP-1 and GIP was quantified, and the localization was observed using immunohistochemistry (p < 0.05). Results: GLP-1 mRNA expression was statistically significantly more upregulated in HM than in HF at 3 weeks. Moreover, GLP-1 mRNA expression was significantly higher in HM than in both SM and HF at 10 weeks. Although a decreasing trend was observed in GIP mRNA expression in both 3- and 10-week-old rats fed on a HFD, a significant difference between HM and SM only occurred at 3 weeks. Furthermore, the GIP mRNA expression of HM was lower than that of HF at 10 weeks. Immunohistochemical staining revealed GLP-1 and GIP expression mainly in the SMG duct system. Moreover, vacuolated cytoplasm in the duct was observed in rats fed on a HFD. Conclusion: Exposure to HFD during pre- and post-natal periods increased GLP-1 mRNA expression in the SMGs of male rats. However, GIP expression decreased following the HFD in male newborns. Furthermore, a decreasing trend of GIP mRNA expression was observed in male newborns after HFD feeding. Sex influenced incretin hormones secretion and obesity-related conditions. HFD during pre- and post-natal periods reprograms the epigenome, contributing to subsequent disease development.

Protein adducts with lipid peroxidation products in patients with psoriasis

Psoriasis, one of the most frequent immune-mediated skin diseases, is manifested by numerous psoriatic lessons on the skin caused by excessive proliferation and keratinization of epidermal cells. These disorders of keratinocyte metabolism are caused by a pathological interaction with the cells of the immune system, including lymphocytes, which in psoriasis are also responsible for systemic inflammation. This is accompanied by oxidative stress, which promotes the formation of lipid peroxidation products, including reactive aldehydes and isoprostanes, which are additional pro-inflammatory signaling molecules. Therefore, the presented review is focused on highlighting changes that occur during psoriasis development at the level of lipid peroxidation products, including 4-hydroxynonenal, 4-oxononenal, malondialdehyde, and acrolein, and their influence on protein structures. Furthermore, we will examine inducing agents of cellular functioning, as well as intercellular signaling. These lipid peroxidation products can form adducts with a variety of proteins with different functions in the body, including proteins within skin cells and cells of the immune system. This is especially true in autoimmune diseases such as psoriasis. For example, these changes concern proteins involved in maintaining redox homeostasis or pro-inflammatory signaling. Therefore, the formation of such adducts should attract attention, especially during the design of preventive cosmetics or anti-psoriasis therapies.

Applications of Antioxidants in Dental Procedures

As people are paying more and more attention to dental health, various dental treatment procedures have emerged, such as tooth bleaching, dental implants, and dental restorations. However, a large number of free radicals are typically produced during the dental procedures. When the imbalance in distribution of reactive oxygen species (ROS) is induced, oxidative stress coupled with oxidative damage occurs. Oral inflammations such as those in periodontitis and pulpitis are also unavoidable. Therefore, the applications of exogenous antioxidants in oral environment have been proposed. In this article, the origin of ROS during dental procedures, the types of antioxidants, and their working mechanisms are reviewed. Additionally, antioxidants delivery in the complicated dental procedures and their feasibility for clinical applications are also covered. Finally, the importance of safety assessment of these materials and future work to take the challenge in antioxidants development are proposed for perspective.

Role of Reactive Oxygen Species in Aging and Age-Related Diseases: A Review

Research on the role of reactive oxygen species (ROS) in the aging process has advanced significantly over the last two decades. In light of recent findings, ROS takes part in the aging process of cells along with contributing to various physiological signaling pathways. Antioxidants being cells' natural defense mechanism against ROS-mediated alteration, play an imperative role to maintain intracellular ROS homeostasis. Although the complete understanding of the ROS regulated aging process is yet to be fully comprehended, current insights into various sources of cellular ROS and their correlation with the aging process and age-related diseases are portrayed in this review. In addition, results on the effect of antioxidants on ROS homeostasis and the aging process as well as their advances in clinical trials are also discussed in detail. The future perspective in ROS-antioxidant dynamics on antiaging research is also marshaled to provide future directions for ROS-mediated antiaging research fields.

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.

N-acetylcysteine supplementation did not reverse mitochondrial oxidative stress, apoptosis, and inflammation in the salivary glands of hyperglycemic rats

Background/objectives

Previous studies have shown that N-acetylcysteine (NAC) supplementation with the simultaneous inclusion of HFD prevents salivary glands from oxidative stress and mitochondrial dysfunction. In this experiment, we examined if NAC supplementation could reverse the harmful effect of HFD on mitochondrial function, reduce the severity of apoptosis, and the activity of pro-oxidative enzymes in the salivary glands of rats with confirmed hyperglycemia.

Subjects/methods

Wistar rats were fed the standard or high-fat (HFD) diet for 10 weeks. After 6 weeks of the experiment, HFD rats were diagnosed with hyperglycemia and for the next 4 weeks, the animals were given NAC intragastrically. In the mitochondrial fraction of the parotid (PG) and submandibular salivary glands (SMG), we assessed redox status, inflammation, and apoptosis.

Results

The inclusion of NAC increased the activity of mitochondrial complexes I and II + III as well as decreased the concentration of interleukin-1β, tumor necrosis factor α, and caspase-3, but only in the parotid glands of rats with hyperglycemia compared to the HFD group. However, N-acetylcysteine supplementation did not reduce the activity of caspase-9 or the Bax/Bcl-2 ratio in PG and SMG mitochondria. In both salivary glands we observed reduced activity of cytochrome c oxidase, NADPH oxidase, and xanthine oxidase, as well as hindered production of ROS and lower ADP/ATP radio, but the levels of these parameters were not comparable to the control group.

Conclusions

We demonstrated that NAC supplementation restores the glutathione ratio only in the mitochondria of the submandibular salivary glands. The supply of NAC did not significantly affect the other measured parameters. Our results indicate that NAC supplementation provides little protection against free radicals, apoptosis, and inflammation in the salivary gland mitochondria of HFD rats. Stimulated salivary secretion in hyperglycaemic rats supplemented with NAC seems to be closely related to mitochondrial respiratory capacity and appropriate ATP level.

Electromagnetic Fields Modify Redox Balance in the Rat Gastrointestinal Tract

Objective: The aim of the study was to assess the influence of electromagnetic fields with divergent physical properties on the prooxidative and antioxidative balances in homogenates of the tongue, salivary glands, esophagus, stomach, and small and large intestines of rats.

Material and Methods: Forty rats were randomly divided into four equal groups, namely, a control group, a group exposed to low-frequency electromagnetic fields (LF-EMFs; frequency: 50 Hz; intensity: 10 kV/m; magnetic induction: 4.3 pT), a group exposed to radiofrequency electromagnetic fields (RF-EMFs) emitted by mobile phones (frequency: 900 MHz), and a group exposed simultaneously to LF-EMFs and RF-EMFs emitted by mobile phones. After 28 consecutive days of the experiment, the following pro- and antioxidative markers were assessed in the gastrointestinal tract homogenates: superoxide dismutase (SOD) and its two isoenzymes (Mn-SOD, Cu,Zn-SOD) catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST), total antioxidative capacity (TAC), total oxidative status (TOS), and malondialdehyde (MDA).

Results: In rats exposed to LF-EMFs, higher concentrations of the markers of prooxidant processes, MDA or TOS, were observed in the salivary glands, esophagus, and small intestine homogenates in comparison with the control group. Additionally, in the group of rats opposite to the control, antioxidant activity was observed. The main differences included a higher activity of Cu,Zn-SOD in homogenates of the tongue, salivary glands, and esophagus as well as decreased activity of CAT in homogenates of the tongue, esophagus, and small intestine. In animals exposed to RF-EMFs, the concentration of TOS was higher in the large intestine than in control rats. The main difference of antioxidant activity was presented by decreased Cu,Zn-SOD in homogenates of the salivary glands, stomach, small and large intestine as well as CAT in homogenates of the tongue, esophagus, stomach, and small and large intestine. Moreover, in rats exposed simultaneously to LF-EMFs and RF-EMFs, a lower concentration of TOS was observed. Antioxidant activity was presented by a decreased activity of CAT in homogenates of the tongue, esophagus, stomach, and small and large intestine in comparison to the control group.

Conclusion: Among those applied in the study, electromagnetic fields of a low-frequency caused the most significant disturbances of oxidative stress in the rat gastrointestinal tract.

Salivary Redox Biomarkers in Insulin Resistance: Preclinical Studies in an Animal Model

Insulin resistance (IR) is a condition of impaired tissue response to insulin. Although there are many methods to diagnose IR, new biomarkers are still being sought for early and noninvasive diagnosis of the disease. Of particular interest in laboratory diagnostics is saliva collected in a stress-free, noninvasive, and straightforward manner. The purpose of the study was to evaluate the diagnostic utility of salivary redox biomarkers in preclinical studies in an animal model. The study was conducted on 20 male Wistar rats divided into two equal groups: a standard diet and a high-fat diet (HFD). In all rats fed the HFD, IR was confirmed by an elevated homeostasis model assessment (HOMA-IR) index. We have shown that IR is responsible for the depletion of the enzymatic (↓superoxide dismutase) and nonenzymatic (↓ascorbic acid, ↓reduced glutathione (GSH)) antioxidant barrier at both the central (serum/plasma) and salivary gland (saliva) levels. In IR rats, we also demonstrated significantly higher concentrations of protein/lipid oxidation (↑protein carbonyls, ↑4-hydroxynoneal (4-HNE)), glycation (↑advanced glycation end products), and nitration (↑3-nitrotyrosine) products in both saliva and blood plasma. Salivary nonenzymatic antioxidants and oxidative stress products generally correlate with their blood levels, while GSH and 4-HNE have the highest correlation coefficient. Salivary GSH and 4-HNE correlate with body weight and BMI and indices of carbohydrate metabolism (glucose, insulin, HOMA-IR) and proinflammatory adipokines (leptin, resistin, TNF-α). These biomarkers differentiate IR from healthy controls with very high sensitivity (100%) and specificity (100%). The high diagnostic utility of salivary GSH and 4-HNE is also confirmed by multivariate regression analysis. Summarizing, saliva can be used to assess the systemic antioxidant status and the intensity of systemic oxidative stress. Salivary GSH and 4-HNE may be potential biomarkers of IR progression. There is a need for human clinical trials to evaluate the diagnostic utility of salivary redox biomarkers in IR conditions.

Association of Tumour Microenvironment with Protein Glycooxidation, DNA Damage, and Nitrosative Stress in Colorectal Cancer

Purpose

In this study, we evaluated the total antioxidant capacity, nitrosative stress, and protein/DNA oxidation and glycoxidation products in patients with colorectal cancer regarding histopathological parameters associated with the tumour microenvironment, such as inflammatory infiltration and tumour budding and compare all determined parameters between tumours located in the right and left side of the colon and normal mucosa.

Patients and Methods

Ferric reducing antioxidant power (FRAP), nitrosative stress (myeloperoxidase (MPO), nitrogen oxide (NO), peroxynitrite, and nitrotyrosine), protein oxidation products (protein carbonyls (PC), total thiols, and ischemia modified albumin (IMA)), protein glycooxidation products (tryptophan, kynurenine, N-formylkynurenine, dityrosine, Amadori product, advanced glycation end products (AGE)) and 8-hydroxydeoxyguanosine (8-OHdG) were measured in homogenates from normal and cancerous tissue of 30 patients with colorectal cancer.

Results

Levels of FRAP (p=0.0009), IMA (p=0.0002), kynurenine (p<0.0001), N-formylkynurenine (p<0.0001), dityrosine (p<0.0001), Amadori products (p=0.0024), AGE (p<0.0001), MPO (p<0.0001), NO (p<0.0001) and nitrotyrosine (p=0.0011) were increased, whereas PC (p=0.0004), tryptophan (p<0.0001), 8-OHdG (p<0.0001) and peroxynitrite (p=0.0003) were decreased in the left-side tumour compared to the right-side tumour and normal mucosa.

Conclusion

Our results showed that colorectal cancer is related with disturbances in antioxidant defense and increased oxidative and nitrosative damages to proteins and DNA. These parameters may be useful for evaluation the progression and differentiation of the tumour location. We also demonstrated that redox indicators may depend on the histological type of the tumour and may influence tumour invasion depth, presence of lymph node and distant metastasis, vascular and neural invasion, inflammatory infiltration, and tumour budding, which are part of the tumour microenvironment.

Salivary gland proteins alterations in the diabetic milieu

Salivary glands are considered the chief exocrine glands of the mouth and physiologically contribute to the maintenance of the homeostasis of the oral cavity. They consist of the parotid, submandibular and sublingual glands, which come in pairs and are collectively called the major glands, and the minor glands, which are much smaller and are dispersed throughout the buccal cavity. Salivary glands are distinguished by their size, amount of saliva secretion and their location in the oral cavity. Salivary glands pathophysiology has been a subject of interest in various worldwide metabolic disorders, including diabetes mellitus. Diabetes mellitus (DM), a global health concern, with a pathological imprint involved in vasculature, promotes microvascular and macrovascular complications among which periodontitis ranks sixth. Indeed, DM has also been directly associated with oral health lesions. Specifically, salivary glands in the context of diabetes have been a focal point of study and emphasis in the research field. There is evidence that relates salivary secretion content and diabetes progression. In this review, we present all the reported evidence of the deregulation of specific salivary proteins associated with the progression of diabetes in parallel with changes in salivary gland morphology, cellular architecture, and salivary secretion and composition more generally.

Aging-Related Metabolic Dysfunction in the Salivary Gland: A Review of the Literature

Aging-related salivary dysfunction commonly induces the poor oral health, including decreased saliva flow and dental caries. Although the clinical significance of the salivary glands is well-known, the complex metabolic pathways contributing to the aging-dysfunction process are only beginning to be uncovered. Here, we provide a comprehensive overview of the metabolic changes in aging-mediated salivary gland dysfunction as a key aspect of oral physiology. Several metabolic neuropeptides or hormones are involved in causing or contributing to salivary gland dysfunction, including hyposalivation and age-related diseases. Thus, aging-related metabolism holds promise for early diagnosis, increased choice of therapy and the identification of new metabolic pathways that could potentially be targeted in salivary gland dysfunction.

Naringenin alleviates myocardial ischemia reperfusion injury by enhancing the myocardial miR-126-PI3K/AKT axis in streptozotocin-induced diabetic rats

Ischemic heart disease (IHD) is a leading cause of death in patients with type 1 diabetes. The key to treating IHD is to restore blood supply to the ischemic myocardium, which inevitably causes myocardial ischemia reperfusion (MI/R) injury. Although naringenin (Nar) prevents MI/R injury, the role of Nar in diabetic MI/R (D-MI/R) injury remains to be elucidated. The PI3K/AKT signaling pathway and microRNA (miR)-126 have previously been shown to serve anti-MI/R injury roles. The present study aimed to investigate the protection of Nar against D-MI/R injury and the role of the miR-126-PI3K/AKT axis. Diabetic rats were treated distilled water or Nar (25 or 50 mg/kg, orally) for 30 days and then exposed to MI/R. The present results revealed that Nar alleviated MI/R injury in streptozotocin (STZ)-induced diabetic rats, as shown below: the reduction myocardial enzymes levels was measured using spectrophotometry, the increase of cardiac viability was detected by MTT assay, the inhibition of myocardial oxidative stress was measured using spectrophotometry and the enhancement of cardiac function were recorded using a hemodynamic monitoring system. Furthermore, Nar upregulated the myocardial miR-126-PI3K/AKT axis in D-MI/R rats. These results indicated that Nar alleviated MI/R injury through upregulating the myocardial miR-126-PI3K/AKT axis in STZ-induced diabetic rats. The current findings revealed that Nar, as an effective agent against D-MI/R injury, may provide an effective approach in the management of diabetic IHD.

Paradoxical sleep deprivation induces oxidative stress in the submandibular glands of Wistar rats

OBJECTIVES

Paradoxical sleep deprivation has been associated with impaired salivary secretion in rats. However, the mechanism that underlies this is not known. Therefore, this study assessed salivary and serum oxidative stress levels following paradoxical sleep deprivation in rats.

METHODS

Twenty-one male Wistar rats randomly divided into three groups of seven rats each as; Control (C); partial sleep-deprived (PSD); and total sleep-deprived (TSD) were used. Malondialdehyde (MDA) concentration, Superoxide dismutase (SOD), and catalase activities were evaluated in saliva, serum, and submandibular glands after seven days of sleep deprivation. Data were expressed as mean ± standard error of the mean and analyzed using one-way ANOVA, Tukey HSD post hoc, and Pearson's correlation tests.

RESULTS

Serum MDA levels were significantly higher in both the TSD and PSD groups compared to the control group whereas only the TSD group showed higher submandibular MDA levels compared to the PSD group and the control group. Submandibular SOD activity was significantly lower in both the TSD and PSD groups compared to the control group. Serum catalase activity was significantly lower in the TSD group only compared to the control group.

CONCLUSIONS

These results have demonstrated for the first time that paradoxical sleep deprivation was associated with changes in the oxidant/antioxidant defense system in the submandibular salivary glands of male Wistar rats which may contribute to impairment in salivary secretion.

Salivary Biomarkers of Oxidative Stress and Inflammation in Stroke Patients: From Basic Research to Clinical Practice

Cerebral stroke is a serious worldwide health problem, as can be seen by the global epidemic of the disease. In this disorder, when the blood flow is compromised by ruptures or blocked arteries, sudden death of neurons is observed as a result of a lack of oxygen and nutrients. Numerous severe problems and frequent complications also exist in stroke patients; therefore, there is an urgent need to develop new therapeutic, diagnostic, and prognostic methods for the disease. At present, the diagnosis of stroke is based on a neurological examination, medical history, and neuroimaging, due to the fact that rapid and noninvasive diagnostic tests are unavailable. Nevertheless, oxidative stress and inflammation are considered key factors in stroke pathogenesis. Oxygen free radicals are responsible for oxidation of lipids, proteins, and DNA/RNA, which in turn contributes to oxidative damage of the brain. Toxic products of the oxidation reactions act cytostatically on the cell by damaging cell membranes and leading to neuronal death by apoptosis or necrosis. Thus, it seems that redox/inflammatory biomarkers might be used in the diagnosis of the disease. Nowadays, saliva is of increasing interest in clinical laboratory medicine. Redox biomarkers could be obtained easily, noninvasively, cheaply, and stress-free from saliva. This minireview is aimed at presenting the current knowledge concerning the use of salivary biomarkers of oxidative stress and inflammation in the diagnosis and prognosis of stroke.

Protective effect of nano vitamin D against fatty degeneration in submandibular and sublingual salivary glands: A histological and ultrastructural study

BACKGROUND

Poor nutritional habits and a low level of physical activity are associated with obesity, leading to increased caloric and fat intakes. A high-fat diet can significantly impact oral health through the accumulation of lipids in the salivary glands, which ultimately affect salivary gland function. Recently, an increasing number of supplement nano-formulations, such as nano vitamin D, have become available. However, only few studies have explored the effects of nano vitamin D on the maintenance of oral health.

OBJECTIVE

This study aimed to compare the histological effects of nano vitamin D to those of regular vitamin D on fatty degeneration in submandibular and sublingual salivary glands using a rat model.

METHODS

Twenty-four adult male albino Sprague-Dawley rats were divided into the following groups: untreated group, high-fat diet group, high-fat diet and regular vitamin D group, and high-fat diet and nano vitamin group.Thereafter, samples of the submandibular and sublingual salivary glands were dissected for histological and electron microscopic studies. Morphometric digital image analysis was used to quantitatively measure the changes in the size and number of acini and secretory granules.

RESULTS

Regular vitamin D had a partial protective effect. However, vitamin D could fully restore cellular structures to their normal state, thereby protecting against fatty degeneration of the salivary tissue and immune cell infiltration, particularly in the submandibular serous tissue. Nano vitamin D was more efficacious than regular vitamin D at restoring the number and size of submandibular serous secretory granules.

CONCLUSION

Employing nano vitamin D as a supplement to high-fat diets could protect against high-fat diet-induced salivary gland damage in rats.

Sestrin2 is involved in the Nrf2-regulated antioxidative signaling pathway in luteolin-induced prevention of the diabetic rat heart from ischemia/reperfusion injury

Luteolin attenuates myocardial ischemia/reperfusion (I/R) injury in diabetes through activating the nuclear factor erythroid 2-related factor 2 (Nrf2)-related antioxidative response. Though sestrin2, a highly conserved stress-inducible protein, is regarded as a modulator of Nrf2 and reduces I/R injury, the effect of sestrin2 on luteolin-induced prevention of the diabetic heart from I/R injury remains unclear. We hypothesized that luteolin could relieve myocardial I/R injury in diabetes by activating the sestrin2-modulated Nrf2 antioxidative response. Diabetes was induced in rats using a single dose of streptozotocin (65 mg kg^-1, i.p.) for 6 weeks, and then luteolin (100 mg kg^-1 d^-1, i.g.), Nrf2 inhibitor brusatol, or sestrin2 blocker leucine was administered for 2 consecutive weeks. After that, the hearts were isolated and exposed to global I/R (30 min/120 min). Luteolin markedly improved cardiac function, myocardial viability and expressions of Nrf2-regulated antioxidative genes, and reduced lactate dehydrogenase release, malondialdehyde, and 8-hydroxydeoxyguanosine in the diabetic I/R hearts. Ca²⁺-induced mitochondrial permeability transition and membrane potential disruption were markedly inhibited in luteolin-treated diabetic ventricular myocytes. All these effects of luteolin were significantly reversed by Nrf2 inhibitor brusatol or sestrin2 inhibitor leucine. Luteolin-induced diminished Keap1 and augmented nuclear translocation and ARE binding activity of Nrf2 were hampered by leucine in the diabetic I/R heart. In addition, luteolin-induced augmented transcription of sestrin2 was markedly blocked by brusatol in the diabetic I/R heart. These data suggest that sestrin2 and Nrf2 positively interact to promote antioxidative actions and attenuate mitochondrial damage, by which luteolin relieves diabetic myocardial I/R injury.

Mental Disorders, Cognitive Impairment and the Risk of Suicide in Older Adults

More than 600 million people are aged 60 years and over are living in the world. The World Health Organization estimates that this number will double by 2025 to 2 billion older people. Suicide among people over the age of 60 is one of the most acute problems. The factors strongly associated with suicide are mentioned: physical illnesses, such as cancer, neurologic disorder, pain, liver disease, genital disorders, or rheumatoid disorders. Moreover, neurologic conditions, especially stroke, may affect decision-making processes, cognitive capacity, and language deficit. In addition to dementia, the most common mental disorders are mood and anxiety disorders. A common symptom of these disorders in the elderly is cognitive impairment. This study aimed to present the relationship between cognitive impairment due to dementia, mood disorders and anxiety, and an increased risk of suicide among older people. Dementia is a disease where the risk of suicide is significant. Many studies demonstrated that older adults with dementia had an increased risk of suicide death than those without dementia. Similar conclusions apply to prodromal dementia Depression is also a disease with a high risk of suicide. Many researchers found that a higher level of depression was associated with suicide attempts and suicide ideation. Bipolar disorder is the second entity in mood disorders with an increased risk of suicide among the elderly. Apart from suicidal thoughts, bipolar disorder is characterized by high mortality. In the group of anxiety disorders, the most significant risk of suicide occurs when depression is present. In turn, suicide thoughts are more common in social phobia than in other anxiety disorders. Suicide among the elderly is a serious public health problem. There is a positive correlation between mental disorders such as dementia, depression, bipolar disorder, or anxiety and the prevalence of suicide in the elderly. Therefore, the elderly should be comprehensively provided with psychiatric and psychological support.

NAC Supplementation of Hyperglycemic Rats Prevents the Development of Insulin Resistance and Improves Antioxidant Status but Only Alleviates General and Salivary Gland Oxidative Stress

Previous studies based on animal models demonstrated that N-acetylcysteine (NAC) prevents oxidative stress and improves salivary gland function when the NAC supplementation starts simultaneously with insulin resistance (IR) induction. This study is the first to evaluate the effect of a 4-week NAC supply on the antioxidant barrier and oxidative stress in Wistar rats after six weeks of high-fat diet (HFD) intake. Redox biomarkers were evaluated in the parotid (PG) and submandibular (SMG) salivary glands and stimulated whole saliva (SWS), as well as in the plasma and serum. We demonstrated that the activity of salivary peroxidase and superoxide dismutase and total antioxidant capacity were significantly higher in PG, SMG, and SWS of IR rats treated with NAC. It appears that in PG and SMG of rats fed an HFD, N-acetylcysteine supplementation abolishes oxidative modifications to proteins (evidenced by decreased content of advanced oxidation protein products (AOPP) and advanced glycation end products (AGE)). Simultaneously, it does not reverse oxidative modifications of lipids (as seen in increased concentration of 8-isoprostanes and 4-hydroxynonenal vs. the control), although it reduces the peroxidation of salivary lipids in relation to the group fed a high-fat diet alone. NAC administration increased protein levels in PG and SMG but did not affect saliva secretion, which was significantly lower compared to the controls. To sum up, the inclusion of NAC supplementation after six weeks of HFD feeding was effective in improving the general and salivary gland antioxidant status. Nevertheless, NAC did not eliminate salivary oxidative stress and only partially prevented salivary gland dysfunction.

High-Sugar Diet Disrupts Hypothalamic but Not Cerebral Cortex Redox Homeostasis

Despite several reports on the relationship between metabolic and neurodegenerative diseases, the effect of a high-sugar diet (HSD) on brain function is still unknown. Given the crucial role of oxidative stress in the pathogenesis of these disorders, this study was the first to compare the effect of an HSD on the activity of prooxidative enzymes, enzymatic and non-enzymatic antioxidants, and protein oxidative damage in the brain structures regulating energy metabolism (hypothalamus) and cognitive functions (cerebral cortex). Male Wistar rats were randomly divided into two groups (n = 10)-control diet (CD) and high-sugar diet (HSD)-for 8 weeks. We showed a decrease in glutathione peroxidase and superoxide dismutase activity and an increase in catalase activity in the hypothalamus of HSD rats compared to controls. The activity of xanthine oxidase and NADPH oxidase and the contents of oxidation (protein carbonyls), glycoxidation (dityrosine, kynurenine and N-formylkynurenine) and protein glycation products (advanced glycation end products and Amadori products) were significantly higher only in the hypothalamus of the study group. The HSD was also responsible for the disruption of antioxidant systems and oxidative damage to blood proteins, but we did not show any correlation between systemic redox homeostasis and the brain levels. In summary, HSD is responsible for disorders of enzymatic antioxidant defenses only at the central (plasma/serum) and hypothalamic levels but does not affect the cerebral cortex. The hypothalamus is much more sensitive to oxidative damage caused by an HSD than the cerebral cortex.

Pro-Oxidant Enzymes, Redox Balance and Oxidative Damage to Proteins, Lipids and DNA in Colorectal Cancer Tissue. Is Oxidative Stress Dependent on Tumour Budding and Inflammatory Infiltration?

This study is the first to assess redox homeostasis in patients with colorectal cancer (CRC) in respect to histopathological parameters associated with the tumour microenvironment such as tumour budding and inflammatory infiltration. Pro-oxidant enzymes (NADPH oxidase (NOX), xanthine oxidase (XO)), antioxidant barrier (Cu,Zn-superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), reduced glutathione (GSH)), redox status (total antioxidant (TAC)/oxidant status (TOS)) and oxidative damage products (advanced glycation end products (AGE), advanced oxidation protein products (AOPP), malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG)) were determined in both the normal and cancerous tissue of 29 CRC patients. The activity of NOX (p < 0.01) and XO (p = 0.01), as well as SOD (p < 0.0001), CAT (p < 0.0001) and TAC level (p < 0.01) were significantly higher in tumour tissue than in normal colon mucosa. Oxidative damage products (AGE-p < 0.01, AOPP-p < 0.001, MDA-p < 0.001, 8-OHdG-p < 0.0001) were also higher in cancerous colon tissue. Furthermore, we observed that CAT (p < 0.05) and XO (p < 0.05) activity depends on the intensity of inflammatory infiltration. Oxidative stress index (OSI) (p < 0.05) and MDA (p < 0.01) values were significantly higher in patients with tumour budding (TB) > 5 versus cases with TB < 5. However, OSI level did not differ significantly between cancer and normal tissue. Our results confirm that CRC is associated with enzymatic/non-enzymatic redox imbalance and increased oxidative damage to proteins, lipids and DNA. The determination of these biomarkers could be useful for the evaluation of the tumour progression.

Disruption of tight junctions contributes to hyposalivation of salivary glands in a mouse model of type 2 diabetes

Tight junction (TJ) plays an important role in regulating paracellular fluid transport in salivary glands; however, little is known about the involvement of TJs in diabetes salivary glands. This study aimed to investigate the alterations of TJs and their possible contribution in diabetes-induced hyposalivation. Here, we observed that the morphologies of submandibular glands (SMGs) were impaired, characterized by enlarged acini accumulation with giant secretory granules, which were significantly reduced in atrophic ducts in SMGs of db/db mice, a spontaneous model of type-2 diabetes. However, the secretory granules were increased and scattered in the acini of diabetes parotid glands (PGs). Other ultrastructural damages including swollen mitochondria, expansive endoplasmic reticulum, and autophagosomes were observed in the diabetes group. The levels of TJ proteins including claudin-1 (Cldn1) and claudin-3 (Cldn3) were increased, whereas those of claudin-4 (Cldn4), occludin (Ocln), and zonula occludens-1 (ZO-1) were decreased in SMGs of db/db mice. Higher Cldn1 and Cldn3 and lower claudin-10 (Cldn10) and Ocln levels were observed in PGs of diabetes mice. Taken together, the structures of SMGs and PGs were impaired in diabetes mice, and the disruption of TJ integrity in both SMGs and PGs may contribute to diabetes-induced hyposalivation.

Decreased basal and stimulated salivary parameters by histopathological lesions and secretory dysfunction of parotid and submandibular glands in rats with type 2 diabetes

Patients with type 2 diabetes mellitus (T2DM) present with dry mouth, polydipsia and taste impairment due to salivary secretion disorder. However, the underlying functional mechanism of T2DM remains unknown. The present study found that T2DM rats had significantly lower salivary flow rate and salivary alpha amylase activity, and attenuated salivary secretion responses to acid stimulation compared with control rats. Histopathological observation found that T2DM rats had inflammatory cell infiltration with increased expressions of IL-6 and TNF-α, oxidative stress, including decreased total superoxide dismutase activity and increased malondialdehyde content, and decreased expressions of β1 adrenergic receptor, cholinergic receptor, aquaporin-5 and protein kinase A in salivary glands, in particular the parotid gland. These results indicated that parotid gland impairment was more severe compared with submandibular gland impairment. Reduced salivary secretion may be associated with histopathological lesions and decreased regulation in secretory pathways in salivary glands.

Salivary Oxidative Stress Increases With the Progression of Chronic Heart Failure

The aim of the study was to evaluate the rate of reactive oxygen species (ROS) production, antioxidant barrier, and oxidative damage in non-stimulated (NWS) and stimulated (SWS) saliva as well as plasma/erythrocytes of 50 patients with chronic heart failure (HF) divided into the two subgroups: NYHA II (33 patients) and NYHA III (17 patients). The activity of superoxide dismutase and catalase was statistically increased in NWS of HF patients as compared to healthy controls. The free radical formation, total oxidant status, level of uric acid, advanced glycation end products (AGE), advanced oxidation protein products and malondialdehyde was significantly elevated in NWS, SWS, and plasma of NYHA III patients as compared to NYHA II and controls. We were the first to demonstrate that with the progression of HF, disturbances of enzymatic and non-enzymatic antioxidant defense, and oxidative damage to proteins and lipids occur at both central (plasma/erythrocytes) and local (saliva) levels. In the study group, we also observed a decrease in saliva secretion, total salivary protein and salivary amylase activity compared to age- and gender-matched control group, which indicates secretory dysfunction of salivary glands in patients with HF. Salivary AGE may be a potential biomarker in differential diagnosis of HF.

The Effect of N-Acetylcysteine on Respiratory Enzymes, ADP/ATP Ratio, Glutathione Metabolism, and Nitrosative Stress in the Salivary Gland Mitochondria of Insulin Resistant Rats

This is the first study to assess the effect of N-acetylcysteine (NAC) on the mitochondrial respiratory system, as well as free radical production, glutathione metabolism, nitrosative stress, and apoptosis in the salivary gland mitochondria of rats with high-fat diet (HFD)-induced insulin resistance (IR). The study was conducted on male Wistar rats divided into four groups of 10 animals each: C (control, rats fed a standard diet containing 10.3% fat), C + NAC (rats fed a standard diet, receiving NAC intragastrically), HFD (rats fed a high-fat diet containing 59.8% fat), and HFD + NAC (rats fed HFD diet, receiving NAC intragastrically). We confirmed that 8 weeks of HFD induces systemic IR as well as disturbances in mitochondrial complexes of the parotid and submandibular glands of rats. NAC supplementation leads to a significant increase in the activity of complex I, II + III and cytochrome c oxidase (COX), and also reduces the ADP/ATP ratio compared to HFD rats. Furthermore, NAC reduces the hydrogen peroxide production/activity of pro-oxidant enzymes, increases the pool of mitochondrial glutathione, and prevents cytokine formation, apoptosis, and nitrosative damage to the mitochondria in both aforementioned salivary glands of HFD rats. To sum up, NAC supplementation enhances energy metabolism in the salivary glands of IR rats, and prevents inflammation, apoptosis, and nitrosative stress.

Salivary Redox Biomarkers in Selected Neurodegenerative Diseases

Neurodegenerative diseases (NDDs), such as Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease, are disorders, which cause irreversible and progressive deterioration of the central nervous system. The pathophysiology of NDDs is still not fully explained; nevertheless, oxidative stress is considered as a critical mediator of cerebral degeneration, brain inflammation, as well as neuronal apoptosis. Therefore, it is not surprising that redox biomarkers are increasingly used in the diagnosis of neurodegenerative diseases. As saliva is a very easy to obtain bioliquid, it seems promising to use this biomaterial in the diagnosis of NDDs. Saliva collection is easy, cheap, stress-free, and non-infectious, and it does not require the help of a specialised medical personnel. Additionally, the concentrations of many salivary redox biomarkers correlate with their content in blood serum as well as the degree of disease progression, which makes them non-invasive indicators of NDDs. This paper reviews the latest knowledge concerning the use of salivary redox biomarkers in the diagnosis and prognosis of selected neurodegenerative diseases.

Salivary Antioxidants and Oxidative Stress in Psoriatic Patients: Can Salivary Total Oxidant Status and Oxidative Status Index Be a Plaque Psoriasis Biomarker?

The aim of our research was to evaluate redox balance parameters and biomarkers of oxidative stress (OS) in nonstimulated and stimulated saliva as well as the blood of patients with plaque psoriasis compared to healthy controls. The study involved 40 patients with plaque psoriasis and 40 generally healthy subjects matched by age and gender to the study group patients. We assayed the concentration/activity of antioxidant enzymes: salivary peroxidase (Px), catalase (CAT), and superoxide dismutase (SOD) measured in unstimulated saliva (NWS), stimulated saliva (SWS), and erythrocytes. In plasma as well as NWS and SWS, we measured the concentration/activity of reduced glutathione (GSH), total antioxidant potential (TAC), total oxidative status (TOS), oxidative stress index (OSI), and markers of oxidative modification of proteins: advanced glycation end products (AGE), advanced oxidation protein products (AOPP), and lipid oxidation products: malondialdehyde (MDA) and total lipid hydroperoxide (LOOH). In NWS and SWS, we also evaluated the rate of reactive oxygen species (ROS) production. The concentration of Px, CAT, and SOD was significantly higher in NWS of patients with plaque psoriasis vs. healthy subjects. In SWS of psoriatic patients, we observed considerably higher concentration of Px and CAT, and in erythrocytes of patients with plaque psoriasis, the concentration of GPx and CAT was significantly higher compared to that in the controls. The levels of AOPP, AGE, MDA, and LOOH were considerably higher in NWS, SWS, and plasma of the study group compared to the controls. The concentration of total protein and salivary amylase was significantly lower in NWS and SWS of psoriatic patients compared to the healthy control. In the course of plaque psoriasis, we observed redox imbalances with prevalence of oxidation reactions. Mechanisms involved in the synthesis/secretion of proteins and activity of amylase were depressed in both glands of psoriatic patients; however, they were more inhibited in the parotid gland compared to the submandibular gland. TOS concentration and OSI value in NWS and SWS may serve as diagnostic biomarkers of plaque psoriasis.

High-Fat Diet Affects Ceramide Content, Disturbs Mitochondrial Redox Balance, and Induces Apoptosis in the Submandibular Glands of Mice

This is the first study to investigate the relationship between ceramides, the mitochondrial respiratory system, oxidative stress, inflammation, and apoptosis in the submandibular gland mitochondria of mice with insulin resistance (IR). The experiment was conducted on 20 male C57BL/6 mice divided into two equal groups: animals fed a high-fat diet (HFD; 60 kcal% fat) and animals fed a standard diet (10 kcal% fat). We have shown that feeding mice HFD induces systemic IR. We noticed that HFD feeding was accompanied by a significant increase in ceramide production (C18 1Cer, C18 Cer, C22 Cer, C24 1Cer, C24 Cer), higher activity of pro-oxidant enzymes (NADPH oxidase and xanthine oxidase), and weakened functioning of mitochondrial complexes in the submandibular glands of IR mice. In this group, we also observed a decrease in catalase and peroxidase activities, glutathione concentration, redox status, increased concentration of protein (advanced glycation end products, advanced oxidation protein products) and lipid (malondialdehyde, lipid hydroperoxide) peroxidation products, and enhanced production of tumor necrosis factor alpha (TNFα) and interleukin 2 (IL-2) as well as pro-apoptotic Bax in the submandibular gland mitochondria. In summary, HFD impairs salivary redox homeostasis and is responsible for enhanced oxidative damage and apoptosis in the submandibular gland mitochondria. The accumulation of some ceramides could boost free radical formation by affecting pro-oxidant enzymes and the mitochondrial respiratory chain.

Antioxidant Barrier, Redox Status, and Oxidative Damage to Biomolecules in Patients with Colorectal Cancer. Can Malondialdehyde and Catalase Be Markers of Colorectal Cancer Advancement?

This study is the first to assess the diagnostic utility of redox biomarkers in patients with colorectal cancer (CRC). Antioxidant barrier (Cu,Zn-superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), uric acid (UA), reduced glutathione (GSH)), redox status (total antioxidant (TAC)/oxidant status (TOS), ferric reducing ability (FRAP)), and oxidative damage products (advanced glycation end products (AGE), advanced oxidation protein products (AOPP), malondialdehyde (MDA)) were measured in serum/plasma samples of 50 CRC patients. The activity of SOD was significantly higher whereas the activity of CAT, GPx and GR was considerably lower in CRC patients compared to the control group (p < 0.0001). Levels of UA, TOS, and OSI and concentrations of AGE, AOPP, and MDA were significantly higher, and the levels of GSH, TAC, and FRAP were considerably lower in CRC patients compared to the healthy controls (p < 0.0001). AUC for CAT with respect to presence of lymph node metastasis was 0.7450 (p = 0.0036), whereas AUC for MDA according to the depth of tumour invasion was 0.7457 (p = 0.0118). CRC is associated with enzymatic/non-enzymatic redox imbalance as well as increased oxidative damage to proteins and lipids. Redox biomarkers can be potential diagnostic indicators of CRC advancement.

Salivary Gland Function, Antioxidant Defence and Oxidative Damage in the Saliva of Patients with Breast Cancer: Does the BRCA1 Mutation Disturb the Salivary Redox Profile?

Oxidative stress plays a key role in breast cancer progression. However, little is still known about the relationship between the BRCA1 mutation, the incidence of breast cancer and oral homeostasis. This is the first study to evaluate the secretory function of salivary glands, biomarkers of redox balance, and oxidative damage to proteins and lipids in the saliva of subjects with the BRCA1 mutation. Ninety eight women were enrolled in the study and allocated to four groups based on molecular DNA testing: generally healthy patients without the BRCA1 mutation, patients with breast cancer but without the BRCA1 mutation, generally healthy patients with the BRCA1 mutation, and patients with both breast cancer and the BRCA1 mutation. We demonstrated that saliva from breast cancer patients with the BRCA1 mutation is characterized by enhanced antioxidant capacity and a higher degree of oxidative damage to proteins and lipids. The BRCA1 mutation can cause a predisposition to early salivary gland dysfunction, both in patients with breast cancer and in healthy individuals, leading to a decrease in salivary proteins. Using cluster analysis, we showed that salivary peroxidase, advanced glycation end-products (AGE), total antioxidant status (TAS) and malondialdehyde (MDA) may have particular clinical significance in non-invasive diagnostics of breast cancer.

The Impact of High-Fat Diet on Mitochondrial Function, Free Radical Production, and Nitrosative Stress in the Salivary Glands of Wistar Rats

Oxidative stress plays a crucial role in the salivary gland dysfunction in insulin resistance; however, the cause of increased free radical formation in these conditions is still unknown. Therefore, the aim of the study was to investigate the effect of high-fat diet (HFD) on the mitochondrial respiratory system, prooxidant enzymes, ROS production, and nitrosative/oxidative stress in the submandibular and parotid glands of rats. The experiment was performed on male Wistar rats divided into two groups (n = 10): control and HFD. The 8-week feeding of HFD affects glucose metabolism observed as significant increase in plasma glucose and insulin as well as HOMA-IR as compared to the control rats. The activity of mitochondrial Complex I and Complex II+III was significantly decreased in the parotid and submandibular glands of HFD rats. Mitochondrial cytochrome c oxidase (COX) activity and the hydrogen peroxide level were significantly increased in the parotid and submandibular glands of the HFD group as compared to those of the controls. HFD rats also showed significantly lower reduced glutathione (GSH) and reduced : oxidized glutathione (GSH : GSSG) ratio, as well as a higher GSSG level in the parotid glands of HFD rats. The activity of NADPH oxidase, xanthine oxidase, and levels of oxidative/nitrosative stress (malonaldehyde, nitric oxide, nitrotyrosine, and peroxynitrite) and inflammation/apoptosis (interleukin-1β and caspase-3) biomarkers were statistically elevated in the HFD group in comparison to the controls. HFD impairs mitochondrial function in both types of salivary glands by enhancing ROS production, as well as stimulating inflammation and apoptosis. However, free radical production, protein nitration, and lipid peroxidation were more pronounced in the parotid glands of HFD rats.

Diagnostic Value of Salivary Markers in Neuropsychiatric Disorders

A growing interest in the usability of saliva has been observed recently. Using saliva as a diagnostic material is possible because it contains a varied range of composites, organic and inorganic like proteins, carbohydrates, and lipids, which are secreted into saliva. Moreover, this applies to drugs and their metabolites. Saliva collection is noninvasive, and self-collection is possible. There is a lack of risk of injuries related to injection with needle, and it is generally safe. Human saliva has been successfully used, for example, in the diagnosis of many systemic diseases like cancers, autoimmunological diseases, infectious diseases (HIV, hepatitis, and malaria), and endocrinological diseases, as well as diseases of the gastrointestinal tract. Also, it is used in toxicological diagnostics, drug monitoring, and forensic medicine. The usefulness of saliva as a biological marker has also been extended to psychiatry. The specificity of mental illness and patients limits or prevents cooperation and diagnosis. In many cases, the use of saliva as a marker seems to be the most sensible choice.

Luteolin Attenuates Cardiac Ischemia/Reperfusion Injury in Diabetic Rats by Modulating Nrf2 Antioxidative Function

Luteolin has been reported to attenuate ischemia/reperfusion (I/R) injury in the diabetic heart through endothelial nitric oxide synthase- (eNOS-) related antioxidative response. Though the nuclear factor erythroid 2-related factor 2 (Nrf2) is regarded as a key endogenous factor to reduce diabetic oxidative stress, whether luteolin reduces cardiac I/R injury in the diabetic heart via enhancing Nrf2 function needs to be clarified. We hypothesized that pretreatment with luteolin could alleviate cardiac I/R injury in the diabetic heart by affecting the eNOS/Nrf2 signaling pathway. The diabetic rat was produced by a single injection of streptozotocin (65 mg/kg, i.p.) for 6 weeks, and then, luteolin (100 mg/kg/day, i.g.), eNOS inhibitor L-NAME, or Nrf2 inhibitor brusatol was administered for the succedent 2 weeks. After that, the isolated rat heart was exposed to 30 min of global ischemia and 120 min of reperfusion to establish I/R injury. Luteolin markedly ameliorated cardiac function and myocardial viability; upregulated expressions of heme oxygenase-1, superoxide dismutase, glutathione peroxidase, and catalase; and reduced myocardial lactate dehydrogenase release, malondialdehyde, and 8-hydroxydeoxyguanosine in the diabetic I/R heart. All these ameliorating effects of luteolin were significantly reversed by L-NAME or brusatol. Luteolin also markedly reduced S-nitrosylation of Kelch-like ECH-associated protein 1 (Keap1) and upregulated Nrf2 and its transcriptional activity. This effect of luteolin on Keap1/Nrf2 signaling was attenuated by L-NAME. These data reveal that luteolin protects the diabetic heart against I/R injury by enhancing eNOS-mediated S-nitrosylation of Keap1, with subsequent upregulation of Nrf2 and the Nrf2-related antioxidative signaling pathway.

Antioxidant Defense, Oxidative Modification, and Salivary Gland Function in an Early Phase of Cerulein Pancreatitis

Acute pancreatitis (AP) is a multifactorial disease characterized by necroinflammatory changes of the pancreas. Our study is the first study which evaluated the relationship between the free radical production, enzymatic and nonenzymatic antioxidants, oxidative damage, and secretory function of the salivary glands of AP rats. Male Wistar rats were divided equally into 2 groups: control (n = 9) and AP (n = 9). AP was induced by intraperitoneal injection with cerulein and confirmed by higher serum amylase and lipase. We have demonstrated that the superoxide dismutase and glutathione reductase activities, as well as reduced glutathione concentration, were significantly decreased in both the parotid and submandibular glands of AP rats as compared to the control rats. The production of free radicals evidenced as dichlorodihydrofluorescein assay and the activity of NADPH oxidase and xanthine oxidase and IL-1β concentration were significantly higher in the parotid and submandibular glands of AP rats compared to the controls. In AP rats, we also showed a statistical increase in oxidation modification products (advanced glycation end products and advanced oxidation protein products), salivary amylase activity, and significant decrease in the total protein content. However, we did not show apoptosis and any morphological changes in the histological examination of the salivary glands of AP rats. To sum up, cerulein-induced AP intensifies production of oxygen free radicals, impairs the redox balance of the salivary glands, and is responsible for higher oxidative damage to these glands. Interestingly, oxidative modification of proteins and dysfunction of the antioxidant barrier are more pronounced in the submandibular glands of AP rats.

Insulin Resistance and Oxidative Stress in the Brain: What's New?

The latest studies have indicated a strong relationship between systemic insulin resistance (IR) and higher incidence of neurodegeneration, dementia, and mild cognitive impairment. Although some of these abnormalities could be explained by chronic hyperglycaemia, hyperinsulinemia, dyslipidaemia, and/or prolonged whole-body inflammation, the key role is attributed to the neuronal redox imbalance and oxidative damage. In this mini review, we provide a schematic overview of intracellular oxidative stress and mitochondrial abnormalities in the IR brain. We highlight important correlations found so far between brain oxidative stress, ceramide generation, β-amyloid accumulation, as well as neuronal apoptosis in the IR conditions.

Eight-Week Consumption of High-Sucrose Diet Has a Pro-Oxidant Effect and Alters the Function of the Salivary Glands of Rats

A high-sucrose diet (HSD) is widely known for its cariogenic effects and promotion of obesity, insulin resistance, type 2 diabetes, and cancer. However, the impact of the HSD diet on the salivary gland function as well as the level of salivary oxidative stress is still unknown and requires evaluation. Our study is the first to determine both redox balance and oxidative injury in the parotid and submandibular glands of rats fed the HSD diet compared to the control group. We have demonstrated that uric acid concentration and the activity of superoxide dismutase and peroxidase varied significantly in both the submandibular and parotid glands of HSD rats vs. the control group. However, enhanced oxidative damage to proteins, lipids, and DNA (increase in advanced glycation end products, advanced oxidation protein products, 4-hydroxynonenal, and 8-hydroxy-2'-deoxyguanosine) was observed only in the parotid glands of HSD rats. Moreover, the HSD diet also reduced the total protein content and amylase activity in both types of salivary glands and decreased the stimulated salivary flow rate. To sum up, an HSD diet reduces salivary gland function and disturbs the redox balance of the parotid as well as submandibular salivary glands. However, the parotid glands are more vulnerable to both antioxidant disturbances and oxidative damage.

Redox Balance, Antioxidant Defense, and Oxidative Damage in the Hypothalamus and Cerebral Cortex of Rats with High Fat Diet-Induced Insulin Resistance

Oxidative stress is a key pathogenic factor in both neurogenerative and metabolic diseases. However, its contribution in the brain complications of insulin resistance is still not well understood. Therefore, the aim of this study was the evaluation of redox homeostasis and oxidative damage in the hypothalamus and cerebral cortex of insulin-resistant and control rats. 16 male Wistar rats were divided into two equal groups (n = 8): the control and high fat diet group (HFD). Prooxidant enzymes (xanthine oxidase and NADPH oxidase); enzymatic and nonenzymatic antioxidants [glutathione peroxidase (GPx), glutathione reductase (GR), catalase (CAT), superoxide dismutase-1 (SOD-1), and uric acid (UA)]; and oxidative damage products [advanced glycation end products (AGE), 4-hydroxynonenal (4-HNE), malondialdehyde (MDA), and 8-hydroxy-2′-deoxyguanosine (8-OHdG)] as well as the total antioxidant capacity (TAC), total oxidant status (TOS), oxidative stress index (OSI), and total ferric reducing ability of sample (FRAP) were evaluated in the hypothalamus and cerebral cortex as well as serum/plasma of HFD-fed and control rats. The activity of prooxidant enzymes was significantly increased in the cerebral cortex and hypothalamus of HFD-fed rats vs. control rats. Additionally, we have showed enhanced antioxidant efficiency in the hypothalamus (↑CAT, ↑UA, ↑TAC, and ↑FRAP) and cerebral cortex (↑GPx, ↑CAT, ↑SOD-1, ↑UA, ↑TAC, and ↑FRAP) of HFD-fed rats. All of the oxidative damage markers (AGE, 4-HNE, MDA, 8-OHdG, and OSI) were significantly increased in the cerebral cortex of insulin-resistant rats, while only 4-HNE and MDA were markedly higher in the hypothalamus of the HFD group. Summarizing, the results of our study indicate an adaptive brain response to the increased production of free radicals under insulin resistance conditions. Despite the increase in antioxidative defense systems, this mechanism does not protect both brain structures from oxidative damages. However, the cerebral cortex is more susceptible to oxidative stress caused by HFD.

Whey Protein Concentrate WPC-80 Intensifies Glycoconjugate Catabolism and Induces Oxidative Stress in the Liver of Rats

The aim of this study was to evaluate the effect of whey protein concentrate (WPC-80) on glycoconjugate catabolism, selected markers of oxidative stress and liver inflammation. The experiment was conducted on male Wistar rats (n = 63). The animals from the study group were administered WPC-80 at a dose of 0.3 or 0.5 g/kg body weight for 7, 14 or 21 days, while rats from the control group received only 0.9% NaCl. In liver homogenates, we assayed the activity of N-acetyl-β-D-hexosaminidase (HEX), β-glucuronidase (GLU), β-galactosidase (GAL), α-mannosidase (MAN), α-fucosidase (FUC), as well as the level of reduced glutathione (GSH), malondialdehyde (MDA), interleukin-1β (IL-1β) and transforming growth factor-β1 (TGF-β1). A significantly higher activity of HEX, GLU, MAN and FUC were found in the livers of rats receiving WPC-80 compared to controls. Serum ALT and AST were significantly higher in the animals supplemented with WPC-80 at a dose of 0.5 g/kg body weight for 21 days. In the same group of animals, enhanced level of GSH, MDA, IL-1β and TGF-β1 were also observed. WPC-80 is responsible for intensive remodelling of liver tissue and induction of oxidative stress especially at a dose of 0.5 g/kg body weight.

Salivary Biomarkers of Oxidative Stress in Children with Chronic Kidney Disease

There are still missing non-invasive biomarkers of chronic kidney disease (CKD) in children. Therefore, the aim of the study was to evaluate oxidative stress indicators in the non-stimulated (NWS) and stimulated saliva (SWS) of CKD children (n = 25) and healthy controls (n = 25). Salivary antioxidants (catalase (CAT), peroxidase (Px), superoxide dismutase (SOD), uric acid (UA), reduced glutathione (GSH), albumin), redox status (total antioxidant capacity (TAC), total oxidant status (TOS), oxidative stress index (OSI)), and oxidative damage products (advanced glycation end products (AGE), advanced oxidation protein products (AOPP), malondialdehyde (MDA)) were evaluated. We have demonstrated the significantly higher activity of SWS GPx and SOD, as well as elevated concentrations of UA and albumin in NWS and SWS of CKD children vs. the control group. TAC, TOS and OSI were significantly higher only in SWS, while oxidative damage products (AGE, AOPP and MDA) were significantly higher in both NWS and SWS of CKD children. ROC analysis showed a considerably high diagnostic value of AOPP in both NWS and SWS of CKD children compared to controls (AUC = 0.92; 0.98). CKD is responsible for disturbances in salivary antioxidant systems and oxidative damage to proteins and lipids. Salivary AOPP can be a potential biomarker of CKD in children.

Whey Protein Concentrate WPC-80 Improves Antioxidant Defense Systems in the Salivary Glands of 14-Month Wistar Rats

Whey protein concentrate (WPC) is characterized by powerful antioxidant properties, but its effect on redox homeostasis of salivary glands of aging organisms is still unknown. In this study, we are the first to evaluate the antioxidant barrier of salivary glands of 14-month Wistar rats fed WPC-80. Total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI), activities of glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT) as well as concentrations of reduced glutathione (GSH) are estimated in the submandibular and parotid glands of rats administered WPC-80 intragastrically for a period of 7 and 14 days. We demonstrate a significant increase in GSH, GPx and SOD in the salivary glands of rats fed WPC-80 for 14 days and a significant increase in TAS, GPx and SOD in the parotid glands of rats fed WPC-80 for 7 days compared to control rats. The beneficial effects of WPC-80 on salivary glands are also demonstrated by lower TOS and OSI in the parotid glands of rats fed WPC-80 compared to the submandibular glands. In summary, we demonstrate that WPC-80 improves redox homeostasis in salivary glands, particularly in the parotid glands of old rats.

Exposure to Ti4Al4V Titanium Alloy Leads to Redox Abnormalities, Oxidative Stress, and Oxidative Damage in Patients Treated for Mandible Fractures

Due to the high biotolerance, favourable mechanical properties, and osseointegration ability, titanium is the basic biomaterial used in maxillofacial surgery. The passive layer of titanium dioxide on the surface of the implant effectively provides anticorrosive properties, but it can be damaged, resulting in the release of titanium ions to the surrounding tissues. The aim of our work was to evaluate the influence of Ti6Al4V titanium alloy on redox balance and oxidative damage in the periosteum surrounding the titanium miniplates and screws as well as in plasma and erythrocytes of patients with mandibular fractures. The study included 31 previously implanted patients (aged 21-29) treated for mandibular fractures and 31 healthy controls. We have demonstrated increased activity/concentration of antioxidants both in the mandibular periosteum and plasma/erythrocytes of patients with titanium mandibular fixations. However, increased concentrations of the products of oxidative protein and lipid modifications were only observed in the periosteum of the study group patients. The correlation between the products of oxidative modification of the mandible and antioxidants in plasma/erythrocytes suggests a relationship between the increase of oxidative damage at the implantation site and central redox disorders in patients with titanium miniplates and screws.

Sources of free radicals and oxidative stress in the oral cavity

OBJECTIVE

An oral cavity is a place especially susceptible to oxidative damage. It is subjected to many environmental pro-oxidative factors or factors that have the ability to generate reactive oxygen species (ROS). The aim of this article is to present the main sources of ROS and oxidative stress in the oral environment.

DESIGN

A literature search was performed using the PubMed and Google Scholar databases.

RESULTS

One of the most important ROS sources in the oral cavity is periodontal inflammation. Other sources of ROS include: xenobiotics (ethanol, cigarette smoke, drugs), food (high-fat diet, high-protein diet, acrolein), dental treatment (ozone, ultrasound, non-thermal plasma, laser light, ultraviolet light), and dental materials (fluorides, dental composites, fixed orthodontic appliances, and titanium fixations). It has been shown that excessive production of ROS in the oral cavity may cause oxidative stress and oxidative damage to cellular DNA, lipids, and proteins, thus predisposing to many oral and systemic diseases.

CONCLUSIONS

Recognition of the exogenous sources of ROS and limitation of exposure to the ROS generating factors can be one of the prophylactic measures preventing oral and systemic diseases. It is suggested that antioxidant supplementation may be helpful in people exposed to excessive production of ROS in the oral cavity system.

A Novel EphA2 Inhibitor Exerts Beneficial Effects in PI-IBS in Vivo and in Vitro Models via Nrf2 and NF-κB Signaling Pathways

Though the detailed pathological mechanism of post-infectious irritable bowel syndrome (PI-IBS) remains unclear, accumulating evidence indicates that oxidative stress and inflammation are implicated in the process of PI-IBS. Oxidative stress and inflammation are regulated by Nrf2 and NF-κB signaling pathways, respectively. EphA2, a member of Eph receptor family, promotes oxidative stress and inflammatory responses via regulation of Nrf2 and NF-κB signaling pathways in various types of human diseases. Understanding the mechanisms by which EphA2 regulate oxidative stress and inflammation in PI-IBS is important for the development of new strategies to treat PI-IBS. However, the effects of ALW-II-41-27, a novel EphA2 inhibitor on PI-IBS and the underlying molecular mechanisms have never been studied. In the present study, we showed that ALW-II-41-27 decreased gastrointestinal motility and abdominal withdrawal reflex (AWR) scores, markedly reduced the levels of oxidative stress markers [4-hydroxy-2-nonenal (4-HNE), protein carbonyl, and 8-hydroxy-2-de-axyguanine (8-OHdG)] and proinflammatory cytokines (TNF-α, IL-6, IL-17, and ICAM-1), and remarkably increased the level of anti-inflammatory cytokine (IL-10) in serum and colon of Trichinella spiralis-infected mice. Moreover, ALW-II-41-27 was effective in suppressing oxidative stress and inflammation in LPS-treated NCM460 colonic cells. Treatment of ALW-II-41-27 reversed the activation of NF-κB and inactivation of Nrf2 in LPS-treated NCM460 cells. Importantly, these protective effects of ALW-II-41-27 were partially inhibited by EphA2 KO and abolished by EphA2 overexpression. In conclusion, EphA2 may represent a promising therapeutic target for patients with PI-IBS and ALW-II-41-27 might function as a novel therapeutic agent for PI-IBS.

Effect of N-Acetylcysteine on Antioxidant Defense, Oxidative Modification, and Salivary Gland Function in a Rat Model of Insulin Resistance

Oxidative stress plays a crucial role in the salivary gland dysfunction in insulin resistance (IR). It is not surprising that new substances are constantly being sought that will protect against the harmful effects of IR in the oral cavity environment. The purpose of this study was to evaluate the effect of N-acetylcysteine (NAC) on oxidative stress and secretory function of salivary glands in a rat model of insulin resistance. Rats were divided into 4 groups: C-normal diet, C + NAC-normal diet + NAC, HFD-high-fat diet, and HFD + NAC. We have demonstrated that NAC elevated enzymatic (superoxide dismutase, catalase, and peroxidase) and nonenzymatic antioxidants (reduced glutathione (GSH) and total antioxidant capacity (TAS)) in the parotid glands of HFD + NAC rats, while in the submandibular glands increased only GSH and TAS levels. NAC protects against oxidative damage only in the parotid glands and increased stimulated salivary secretion; however, it does not increase the protein secretion in the both salivary glands. Summarizing, NAC supplementation prevents the decrease of stimulated saliva secretion, seen in the HFD rats affected. NAC improves the antioxidative capacity of the both glands and protects against oxidative damage to the parotid glands of IR rats.

Oxidative Modification of Biomolecules in the Nonstimulated and Stimulated Saliva of Patients with Morbid Obesity Treated with Bariatric Surgery

Morbid obesity leads to progressive failure of many human organs and systems; however, the role of oxidative damage to salivary composition is still unknown in the obese patients. In this study, we assessed the effect of bariatric surgery on oxidative damage in nonstimulated (NS) and stimulated (S) whole saliva. The study included 47 subjects with morbid obesity as well as 47 age- and gender-matched healthy volunteers. Oxidative modifications to lipids (4-hydroxynonenal (4-HNE) and 8-isoprostanes (8-isoP)), proteins (advanced oxidation protein products (AOPP) and protein carbonyl groups (PC)), and DNA (8-hydroxy-D-guanosine (8-OHdG)) were analyzed in morbidly obese patients before and after bariatric surgery as well as in the healthy controls. The concentrations of 8-isoP, AOPP, PC, and 8-OHdG were significantly higher in both NS and S of patients with morbid obesity than in the control patients and compared to the results obtained 6 months after bariatric surgery. The levels of oxidative damage markers were also higher in S versus NS of morbidly obese patients. In summary, morbid obesity is associated with oxidative damage to salivary proteins, lipids, and DNA, while bariatric treatment generally lowers the levels of salivary oxidative damage.

Antioxidant Defence, Oxidative Stress and Oxidative Damage in Saliva, Plasma and Erythrocytes of Dementia Patients. Can Salivary AGE be a Marker of Dementia?

Oxidative stress plays a crucial role in dementia pathogenesis; however, its impact on salivary secretion and salivary qualities is still unknown. This study included 80 patients with moderate dementia and 80 healthy age- and sex-matched individuals. Salivary flow, antioxidants (salivary peroxidase, catalase, superoxide dismutase, uric acid and total antioxidant capacity), and oxidative damage products (advanced oxidation protein products, advanced glycation end products (AGE), 8-isoprostanes, 8-hydroxy-2’-deoxyguanosine and total oxidant status) were estimated in non-stimulated and stimulated saliva, as well as in plasma and erythrocytes. We show that in dementia patients the concentration/activity of major salivary antioxidants changes, and the level of oxidative damage to DNA, proteins and lipids is increased compared to healthy controls. Non-stimulated and stimulated salivary secretions were significantly reduced in dementia patients. The deterioration in mini mental state examination (MMSE) score correlated with salivary AGE levels, which when considered with receiver operating characteristic (ROC) analysis, suggests their potential role in the non-invasive diagnosis of dementia. In conclusion, dementia is associated with disturbed salivary redox homeostasis and impaired secretory function of the salivary glands. Salivary AGE may be useful in the diagnosis of dementia.

Chronic high-protein diet induces oxidative stress and alters the salivary gland function in rats

OBJECTIVE

Chronic high protein intake leads to an increase in reactive oxygen species (ROS) generation. However, there is no data on the impact of high-protein diet on the antioxidant barrier, oxidative stress and secretory function in the salivary glands of healthy individuals.

DESIGN

16 male Wistar rats were randomly divided into 2 groups (n=8): normal protein (C) and high-protein diet (HP) for 8 weeks. Salivary antioxidants: peroxidase (Px), catalase (CAT), superoxide dismutase 1 (SOD 1), uric acid (UA), total antioxidant status (TAS), total oxidant status (TOS) and the oxidative stress index (OSI), as well as protein carbonyls (PC), 4-hydroxynonenal protein adduct (4-HNE protein adduct), 8-isoprostanes (8-isoP), 8-hydroxy-2'-deoxyguanosine (8-OHdG) and protein content were determined in the salivary glands and plasma. Salivary unstimulated and stimulated flow rates were examined.

RESULTS

Parotid Px, TAS, UA, TOS, OSI, PC were significantly higher, the total protein content was statistically lower in the HP group as compared to the control. Submandibular UA, TOS, OSI, 8-isoP, 4-HNE-protein adduct, 8-OHdG were statistically elevated, SOD 1 and Px were significantly lower in the HP group as compared to the control rats. The unstimulated salivary flow rate was significantly depressed in the HP group as compared to the controls.

CONCLUSIONS

Higher antioxidant capacity in the parotid glands of HP rats vs. control rats seems to be a response to a higher ROS formation. In the submandibular glands severe oxidative modification of almost all cellular components was observed. Administration of HP resulted in the weakening of the salivary gland function.

The Redox Balance in Erythrocytes, Plasma, and Periosteum of Patients with Titanium Fixation of the Jaw

Titanium miniplates and screws are commonly used for fixation of jaw fractured or osteotomies. Despite the opinion of their biocompatibility, in clinical practice symptoms of chronic inflammation around the fixation develop in some patients, even many years after the application of miniplates and screws. The cause of these complications is still an unanswered question. Taking into account that oxidative stress is one of the toxic action of titanium, we have evaluated the antioxidant barrier as well as oxidative stress in the erythrocytes, plasma and periosteum covering the titanium fixation of the jaw. The study group was composed of 32 patients aged 20–30 with inserted miniplates and screws. The antioxidant defense: catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase-1 (SOD1), uric acid (UA), total antioxidant capacity (TAC), as well as oxidative damage products: advanced oxidation protein products (AOPP), advanced glycation end products (AGE), dityrosine, kynurenine, N-formylkynurenine, tryptophan, malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), total oxidant status (TOS), and oxidative status index (OSI) were evaluated. SOD1 activity (↓37%), and tryptophan levels (↓34%) showed a significant decrease while AOPP (↑25%), TOS (↑80%) and OSI (↑101%) were significantly elevated in maxillary periosteum of patients who underwent bimaxillary osteotomies as compared to the control group. SOD-1 (↓55%), TAC (↓58.6%), AGE (↓60%) and N-formylkynurenine (↓34%) was statistically reduced while AOPP (↑38%), MDA (↑29%), 4-HNE (↑114%), TOS (↑99%), and OSI (↑381%) were significantly higher in the mandibular periosteum covering miniplates/screw compared with the control tissues. There were no correlations between antioxidants and oxidative stress markers in the periosteum of all patients and the blood. As exposure to the Ti6Al4V titanium alloy leads to disturbances of redox balance in the periosteum surrounding titanium implants of the maxilla and the mandible so antioxidant supplementation should be recommended to the patients undergoing treatment of dentofacial deformities with the use of titanium implants. The results we obtained may also indicate a need to improve the quality of titanium jaw fixations through increase of TiO₂ passivation layer thickness or to develop new, the most highly biodegradable materials for their production.

Lysosomal Exoglycosidase Profile and Secretory Function in the Salivary Glands of Rats with Streptozotocin-Induced Diabetes

Before this study, there had been no research evaluating the relationship between a lysosomal exoglycosidase profile and secretory function in the salivary glands of rats with streptozotocin- (STZ-) induced type 1 diabetes. In our work, rats were divided into 4 groups of 8 animals each: control groups (C2, C4) and diabetic groups (STZ2, STZ4). The secretory function of salivary glands-nonstimulated and stimulated salivary flow, α-amylase, total protein-and salivary exoglycosidase activities-N-acetyl-β-hexosaminidase (HEX, HEX A, and HEX B), β-glucuronidase, α-fucosidase, β-galactosidase, and α-mannosidase-was estimated both in the parotid and submandibular glands of STZ-diabetic and control rats. The study has demonstrated that the activity of most salivary exoglycosidases is significantly higher in the parotid and submandibular glands of STZ-diabetic rats as compared to the healthy controls and that it increases as the disease progresses. Reduced secretory function of diabetic salivary glands was also observed. A significant inverse correlation between HEX B, α-amylase activity, and stimulated salivary flow in diabetic parotid gland has also been shown. Summarizing, STZ-induced diabetes leads to a change in the lysosomal exoglycosidase profile and reduced function of the salivary glands.