Antioxidant enzymatic defense in salivary glands of streptozotocin-induced diabetic rats: a temporal study

Antox targeting AGE/RAGE cascades to restore submandibular gland viability in rat model of type 1 diabetes

Diabetes mellitus (DM) is a chronic disorder of glucose metabolism that threatens several organs, including the submandibular (SMG) salivary glands. Antox (ANX) is a strong multivitamin with significant antioxidant benefits. The goal of this study was to demonstrate the beneficial roles of ANX supplementation in combination with insulin in alleviating diabetic SMG changes. For four weeks, 30 rats were divided into equal five groups (n = 6): (1) control group; (2) diabetic group (DM), with DM induced by streptozotocin (STZ) injection (50 mg/kg i.p.); (3) DM + ANX group: ANX was administrated (10 mg/kg/day/once daily/orally); (4) DM + insulin group: insulin was administrated 1U once/day/s.c.; and (5) DM + insulin + ANX group: co-administrated insulin. The addition of ANX to insulin in diabetic rats alleviated hyposalivation and histopathological alterations associated with diabetic rats. Remarkably, combined ANX and insulin exerted significant antioxidant effects, suppressing inflammatory and apoptotic pathways associated with increased salivary advanced glycation end-product (AGE) production and receptor for advanced glycation end-product expression (RAGE) activation in diabetic SMG tissues. Combined ANX and insulin administration in diabetic rats was more effective in alleviating SMG changes (functions and structures) than administration of insulin alone, exerting suppressive effects on AGE production and frustrating RAGE downstream pathways.

Assessment of redox state and biochemical parameters of salivary glands in streptozotocin-induced diabetic male rats treated with mate tea (Ilex paraguariensis)

OBJECTIVE

The study aimed to assess the effects of mate tea [Ilex paraguariensis] on the redox state and biochemical parameters of salivary glands in diabetic male rats.

DESIGN

Twenty-four male Wistar rats (3 months old) were randomly divided into groups (n = 8 per group): control rats that received water (C); diabetic rats that received water (D); diabetic rats treated with mate tea (DMT). The treated streptozotocin-induced diabetic rats were given mate tea powder by intragastric gavage at a dose of 20 mg/kg daily for 28 days. Content of total protein, amylase, oxidative lipid damage, measured as thiobarbituric acid reactive substances (TBARs), oxidative protein damage, measured as protein carbonyl, total antioxidant capacity, uric acid, reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were examined by the spectrophotometric method in the parotid and submandibular glands.

RESULTS

The D group showed lower total protein, amylase, TBARs, protein carbonyl, total antioxidant capacity, GSH, uric acid, and GPx than the C group in both salivary glands, as well as higher SOD and CAT activities. The DMT group showed higher total protein, amylase, total antioxidant capacity, GSH, uric acid, and GPx than the D group in both salivary glands. Moreover, mate tea increased SOD in the parotid gland and CAT in the submandibular gland of diabetic rats but did not influence TBARs and protein carbonyl in either salivary gland compared to D group.

CONCLUSION

Mate tea increased tissue protein synthesis and improved antioxidant defenses in the salivary glands of streptozotocin-induced diabetic male rats.

Assessment of redox state and biochemical parameters of salivary glands in rats treated with anti-obesity drug sibutramine hydrochloride

OBJECTIVES

To investigate the effects of anti-obesity drug sibutramine hydrochloride (SB) on redox state and biochemical parameters in the salivary glands.

MATERIALS AND METHODS

Adult male Wistar rats were randomly divided into the following groups (n = 8 per group): control rats treated with vehicle (C) and rats treated with SB (10 mg/kg/day) by intragastric gavage for 28 days. The parotid (PG) and submandibular (SMG) glands were processed using histomorphometric analysis, and total protein, amylase, mucin, and oxidative damage to lipids were determined by measuring the formation of thiobarbituric acid reactive substances (TBARS), total antioxidant capacity (TAC), uric acid (UA), total glutathione (tGSH), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), and AKT phosphorylation.

RESULTS

SB decreased the acinar area, and increased the stromal area in PG, while no effect on the morphometric parameters was observed in SMG. SB also increased oxidative damage to lipids (TBARs). The SB group showed lower total protein, amylase, TAC, UA, tGSH, SOD, CAT, and GPx than the C group in PG, while in SMG, SB decreased total protein, mucin, tGSH, SOD, CAT, and GPx. However, increased AKT phosphorylation observed in both salivary glands suggests that SB exerts low-intensity oxidative stress.

CONCLUSIONS

SB impaired enzymatic and non-enzymatic antioxidant defenses in the salivary glands of rats.

CLINICAL RELEVANCE

Chronic treatment with SB could mitigate salivary gland dysfunction due to disturbance of redox state.

Antioxidant effect of chamomile tea on the salivary glands of streptozotocin-induced diabetic rats

This study aimed to analyze oxidative stress and the activity of antioxidant enzymes in the salivary glands of streptozotocin (STZ)-induced diabetic rats with ad libitum consumption of chamomile tea in substitution of water for 21 days. Rats were divided in two control groups (untreated control and treated control) and two diabetic groups (untreated diabetic and treated diabetic). Superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) activities, total antioxidant status (TAS), and malondialdehyde (MDA) concentrations were determined. The chemical composition of the chamomile essential oil revealed 39 compounds, accounting for 93.5% of the total oils. The polyphenolic profile of the tea showed the presence of apigenin, luteolin, umbelliferone, and esculetin. SOD, GPx, CAT, and TAS levels were lower in the parotid (PA) diabetic glands, but treatment increased their concentration in both the submandibular (SM) and PA diabetic salivary glands. Increased MDA levels were observed in the PA diabetic glands, which were decreased by the consumption of chamomile tea with a reduction in hyperglycemia compared to that in untreated diabetic rats. However, the SM diabetic glands showed no difference in the MDA content. The consumption of chamomile tea prevented oxidative stress in the PA glands of diabetic rats, exhibiting hypoglycemic and antioxidant effects. Thus, chamomile tea could be a potential candidate for preventing oral complications in diabetes mellitus.

Effect of Tungstate Administration on the Lipid Peroxidation and Antioxidant Parameters in Salivary Glands of STZ-Induced Diabetic Rats

Sodium tungstate is an alternative to reduce hyperglycemia for the treatment of diabetes. In previous work, we showed that the administration of sodium tungstate increased the specific activity of salivary amylase in the parotid gland. Here, we investigated the effect of the administration of sodium tungstate on the lipid peroxidation and some antioxidant parameters in the submandibular (SM) and parotid (PA) salivary glands of streptozotocin (STZ)-induced diabetic rats. Thirty-two male Wistar rats were divided into four groups (n = 8, each): control (C), control treated with sodium tungstate (CT), diabetic (D), and diabetic treated with sodium tungstate (CT). Sodium tungstate (2 mg/ml) was administered to the STZ-induced diabetic rats for 15 days. Malondialdehyde (MDA), reduced (GSH) and oxidized (GSSG) glutathione, and blood glucose concentrations were quantified. In addition, superoxide dismutase (SOD) and catalase (CAT) activities were assessed. Results revealed that diabetes caused an increase in MDA concentration in both glands, a reduction in the SOD activity in SM, and an increase in catalase activity in PA glands. Administration of sodium tungstate reduced the blood glucose levels and normalized the SOD activity in the SM and MDA levels in both glands of the STZ-induced diabetic rats. Catalase activity was increased in PA glands of diabetic and tungstate-treated animals (p < 0.05). The GSH/GSSG ratio was increased in SM glands of tungstate-treated animals (p < 0.05). Overall, the reduction of hyperglycemia by sodium tungstate reduced lipid peroxidation and caused alterations in the antioxidant system in the salivary glands of STZ-induced diabetic rats.

Salivary Redox Biomarkers in the Course of Caries and Periodontal Disease

Caries are a pathological process of extracorporeal nature, characterized by demineralization of inorganic substances as well as proteolysis triggered by acids produced by bacteria present in dental plaque, as a result of metabolism of sugars of both external and internal origin. Periodontal disease, on the other hand, is a multifactorial degenerative disease associated with inflammation, involving a group of tissues that surround the dental cervix and root of the tooth. It is believed that one of the mechanisms in the etiopathogenesis of caries and periodontitis are disorders of local and/or general oxidative stress (OS) parameters. Numerous clinical studies have confirmed the relationship between oxidative stress markers and oral diseases. In most analyzed studies, technical and biological variability was so high that none of the markers so far has proven suitable for routine clinical use. The aim of systematic reviews of the literature is to present the existing studies on OS parameters, mainly concerning the activity of antioxidant enzymes in saliva of patients with caries and periodontitis.

Impact of Acute Pancreatic Injury on Sphingolipid Metabolism in the Salivary Glands

Acute pancreatic injury can be related to both parenchymal (responsible for exocrine functions) and islet (mainly β-cells, responsible for endocrine functions) damage. During embryonic development, both the salivary glands and the pancreas originate from the foregut, which explains many of the observed histological and functional similarities between these two organs. The relationship between several diseases of the pancreas and salivary glands, resulting from morphological and functional similarities, is well established. Sphingolipids constitute a class of biologically active molecules involved in numerous physiological and pathological processes, including acute pancreatitis (AP) and diabetes mellitus. However, the effect of AP on sphingolipid metabolism in the salivary glands remains uncertain. In the presented study, we examined the effect of AP and type 1 diabetes mellitus on sphingolipid metabolism in the salivary glands of rats. We demonstrated that acute pancreatic injury, related to both exocrine and endocrine functions, affects the metabolism of sphingolipids in the parotid, but not submandibular, salivary glands.

Effect of vitamin C and E on oxidative stress and antioxidant system in the salivary glands of STZ-induced diabetic rats

OBJECTIVE

We examined the effects of vitamin C and E supplementation in the prevention of oxidative stress in the salivary glands of STZ-induced diabetic rats.

DESIGN

Forty-eight male Wistar rats were divided into six groups (n = 8 in each): control (C), control supplemented with vitamin C (Cvc) and E (Cve), diabetic (D), and diabetic supplemented with vitamin C (Dvc) and E (Dve). Vitamin C (150 mg/kg) and E (300 mg/kg) were daily administered for 21 days. Serum ascorbic acid and α-tocopherol levels were quantified. Glandular levels of hydrogen peroxide (H₂O₂), superoxide anion (O₂^-), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), catalase (CAT), malondialdehyde (MDA) and the total antioxidant status (TAS) were estimated.

RESULTS

Vitamin C and E levels were reduced in D group. Vitamin C decreased the levels of O₂^- in the salivary gland of diabetic rats. Vitamin E increased the concentration of O₂^- in PA gland of diabetic animals. In the SM gland of the diabetic group, MDA, SOD, GPx and TAS increased. Dve presented reduced SOD activity and increased GR, GPx, and MDA. Dve increased GPx, Gr and TAS levels. In the PA gland, MDA, SOD, CAT, GPx, GR, and TAS were similar in C and D. TAS, SOD, CAT, GPx, and GR increased in Dvc. Vitamin E supplementation resulted in increased MDA and CAT levels and reduced SOD activity.

CONCLUSION

In the SM glands of the diabetic rats, vitamin C supplementation improved the antioxidant system, while vitamin E acted as pro-oxidant.

Oxidative stress and the antioxidant system in salivary glands of rats with experimental chronic kidney disease

OBJECTIVE

This study aims to analyze the presence of oxidative stress and activity of the antioxidant system in the parotid and submandibular salivary glands of rats with Chronic Kidney Disease (CKD).

DESIGN

Sixteen male wistar rats were divided into two groups (n = 8, each): control rats and rats with CKD. CKD was induced by 5/6 nephrectomy. Blood urea nitrogen and serum creatinine clearance were quantified. Malondialdehyde, superoxide dismutase, glutathione peroxidase, glutathione reductase, catalase, total antioxidant status, ascorbic acid, α-tocopherol, superoxide anion, and hydrogen peroxide concentrations were assessed.

RESULTS

In CKD rats, blood urea nitrogen, serum creatinine, and proteinuria concentrations were increased, while creatinine clearance was reduced. In the submandibular gland, superoxide anion concentration was increased significantly (p < 0.05). Hydrogen peroxide and superoxide anion concentrations were reduced in the parotid gland. CKD rats presented increased malondialdehyde concentration, total antioxidant status, superoxide dismutase, and glutathione reductase activities only in the parotid gland (p < 0.05).

CONCLUSION

Oxidative stress and changes in the antioxidant system were found in the parotid and submandibular salivary glands in an experimental model of CKD induced by 5/6 nephrectomy.

Intravenous laser wavelength radiation effect on LCAT, PON1, catalase, and FRAP in diabetic rats

The main purpose of this study is to evaluate the effect of intravenous irradiation of different low-level laser wavelengths on the activity of lecithin-cholesterol acyltransferase (LCAT), paraoxonase (PON1), catalase, and ferric reducing ability of plasma (FRAP) in diabetic rats. First, diabetes was induced in rats using streptozotocin (STZ). Enzymes' activity was measured in the blood samples and compared before and after intravenous laser blood irradiation. We used four continuous-wave lasers-IR (λ = 808 nm), Red (λ = 638 nm), Green (λ = 532 nm), and Blue (λ = 450 nm)-to compare the wavelength's effect on different enzymes' activity. Laser power was fixed at 0.01 mW and laser energy was changed by 2-, 4-, 6-, and 8-min time of radiations.The enzymes' activity of blood samples was measured 2, 6, and 24 h after radiation. The results show an increase in the activity of different enzymes when compare with diabetic non-radiated samples. More importantly, with a constant laser energy, the enzymes' activity increased with decreasing laser wavelength. It is important to note that with a constant laser energy, as the wavelength decreases, the photon energy increases and the number of photons decrease, while the enzyme's activity elevation increases. As a result, we can conclude that in intravenous low-level laser therapy, photon energy is more important than the number of photons even if their product, energy, is kept constant.

Effect of Low-Level Laser Irradiation on the Function of Glycated Catalase

Introduction: The aim of this work is to evaluate the effect of low-level laser irradiation (LLLI), by lasers with different wavelengths, on glycated catalase enzyme in vitro experimentally. Methods: This is done by measuring the activity and structure properties of glycated catalase enzyme. The structure properties were evaluated with circular dichroism (CD) and fluoroscopy methods. Three continuous wave (CW) lasers in the visible spectrum (λ =450, 530, 638 nm) and a 100-ns pulsed laser in the infrared spectrum (λ =905 nm) were chosen for comparison. For the infrared laser, same effects have been investigated for different energy doses. The effect of photon energy (hυ) at different wavelengths was measured on activity, CD, and fluoroscopy properties of catalase, and compared with the control group (samples without irradiation). The energy intensity of laser should not exceed 0.1 J/cm² . Experiments were performed on glycated catalase between 2 to 16 weeks after glycation of catalase. The LLLI effect was also investigated on the samples, by comparing the catalase activity, CD and fluoroscopy for different wavelengths. Results: Our results indicated, the decrease in catalase activity as a function of glycation time (weeks) for all samples, and a slight increase on its activity by different laser wavelengths irradiation for any fixed period of glycation time. Finally, the catalase activity has been increased as the laser's photon energy (hυ) intensified. More specifically, the blue laser (λ =450 nm) had the most and the red laser (λ =638 nm) had the least effect, and the green laser (λ =530 nm) had the medium effect on catalase activity as well. Furthermore, pulsed laser had an additional effect by increasing energy dosage. Conclusion: As we expected in all experiments, an increase in the catalase activity was coincident with a decrease in the catalase fluoroscopy and CD parameters.

Bone marrow-derived mesenchymal stem cells ameliorate parotid injury in ovariectomized rats

BACKGROUND AIMS

Parotid hypofunction causes life-disrupting effects, and there are no effective medications for xerostomia. We hypothesized that mesenchymal stem cells (MSCs) have repairing effects on parotid glands of ovariectomized (OVX) rats.

METHODS

Forty-five adult female rats were divided into three equal groups: group I (Control group), group II (OVX-group) and group III (OVX rats that received MSCs at 4 and 8 weeks post-ovariectomy). At 12 weeks post-ovariectomy, histological (Masson's trichrome and periodic acid-Schiff with alcian blue stains), immunohistochemical (caspase-3 and CD44) and morphometric studies and salivary flow rate and saliva pH determination were carried out.

RESULTS

Histologically, the OVX group displayed numerous irregular vacuolated acini, thickened septa with marked cellular infiltration and vascular congestion. Degenerated organelles and few or irregular secretory granules with a different density were observed. Caspase-3-positive cells were highly expressed. MSC-treated glands exhibited a considerable degree of preservation of glandular architecture with numerous CD44-expressing and few caspase-3-expressing cells. Significant decrease of the salivary flow rate in the OVX group was detected, which reverted to normal levels in group III.

CONCLUSIONS

MSCs ameliorated the damaging effects of ovariectomy on the parotid glands.

Sphingolipids metabolism in the salivary glands of rats with obesity and streptozotocin induced diabetes

Diabetes is considered a major public health problem affecting millions of individuals worldwide. Remarkably, scientific reports regarding salivary glands sphingolipid metabolism in diabetes are virtually non‐existent. This is odd given the well‐established link between the both in other tissues (e.g., skeletal muscles, liver) and the key role of these glands in oral health preservation. The aim of this paper is to examine sphingolipids metabolism in the salivary glands in (pre)diabetes (evoked by high fat diet feeding or streptozotocin). Wistar rats were allocated into three groups: control, HFD‐, or STZ‐diabetes. The content of major sphingolipid classes in the parotid (PSG) and submandibular (SMSG) glands was assessed via chromatography. Additionally, Western blot analyses were employed for the evaluation of key sphingolipid signaling pathway enzyme levels. No changes in ceramide content in the PSG were found, whereas an increase in ceramide concentration for SMSG of the STZ group was observed. This was accompanied by an elevation in SPT1 level. Probably also sphingomyelin hydrolysis was increased in the SMSG of the STZ‐diabetic rats, since we observed a significant drop in the amount of SM. PSG and SMSG respond differently to (pre)diabetes, with clearer pattern presented by the later gland. An activation of sphingomyelin signaling pathway was observed in the course of STZ‐diabetes, that is, metabolic condition with rapid onset/progression. Whereas, chronic HFD lead to an inhibition of sphingomyelin signaling pathway in the salivary glands (manifested in an inhibition of ceramide de novo synthesis and accumulation of S1P).

Insulin Resistance and Obesity Affect Lipid Profile in the Salivary Glands

In today's world wrong nutritional habits together with a low level of physical activity have given rise to the development of obesity and its comorbidity, insulin resistance. More specifically, many researches indicate that lipids are vitally involved in the onset of a peripheral tissue (e.g., skeletal muscle, heart, and liver) insulin resistance. Moreover, it seems that diabetes can also induce changes in respect of lipid composition of both the salivary glands and saliva. However, judging by the number of research articles, the salivary glands lipid profile still has not been sufficiently explored. In the current study we aim to assess the changes in the main lipid fractions, namely, triacylglycerols, phospholipids, free fatty acids, and diacylglycerols, in the parotid and the submandibular salivary glands of rats exposed to a 5-week high fat diet regimen. We observed that the high caloric fat diet caused a significant change in the salivary glands lipid composition, especially with respect to PH and TG, but not DAG or FFAs, classes. The observed reduction in PH concentration is an interesting phenomenon frequently signifying the atrophy and malfunctions in the saliva secreting organs. On the other hand, the increased accumulation of TG in the glands may be an important clinical manifestation of metabolic syndrome and type 2 diabetes mellitus.

iTRAQ-based quantitative proteomic analysis of submandibular glands from rats with STZ-induced hyperglycemia

The impairment of salivary glands activity is often connected to the complaints of dry-mouth and subsequent degradation of the periodontium of diabetic patients. In this context, submandibular glands (SMGs) play a central role in saliva production and so the understanding of the molecular pathways affected is of paramount importance. Using a streptozotocin-induced hyperglycemia rat model and two different time points (2 and 4 months), we applied mass spectrometry-based proteomic techniques, validated with standard western blot analysis, to identify and quantify the effect of chronic hyperglycemia on the proteome of SMGs. We observed significant variations of proteins such as kallikreins, protein S100A6 or annexins. After 2 months of hyperglycemia, we observed an early phase response characterized by a significant increase of protein S100A6, linked to the inflammatory response, together with the impairment of metabolic and energy production processes. On the other hand, vesicular transport appeared to be favoured in such conditions. Interestingly, in a long-term response to hyperglycemia after 4 months of exposure, we observed a general attenuation of the variations. In conclusion, we present data that support the existence of an adaptation of the gland to long-term stress.

Laser irradiation affects enzymatic antioxidant system of streptozotocin-induced diabetic rats

The aim of the present study was to analyze the effect of low-power laser irradiation in the antioxidant enzymatic system of submandibular (SMG) and parotid (PG) salivary glands of streptozotocin-induced diabetic rats. The animals were randomly divided into six groups: three diabetic groups (D0, D5, and D20) and three non-diabetic groups (C0, C5, and C20), according to laser dose received (0, 5, and 20 J/cm(2), respectively). Areas of approximately 1 cm(2) were demarcated in the salivary glands (each parotid and both submandibular glands) and after irradiated according to Simões et.al. (Lasers Med Sci 24:202-208, 2009). A diode laser (660 nm/100 mW) was used, with laser beam spot of 0.0177 cm(2). The group treated with 5 J/cm(2) laser dose was subjected to irradiation for 1 min and 4 s (total irradiation time) and the group treated with 20 J/cm(2) laser dose was subjected to irradiation for 4 min and 16 s. Twenty-four hours after irradiation the animals were euthanized and the salivary glands were removed for biochemical analysis. The total antioxidant values (TA), the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase enzymes were determined. SOD and CAT activities, as well as TA were higher in SMG of irradiated diabetic rats. However, in SMG of non-diabetic rats, laser irradiation decreased TA values and led to an increase in the CAT activity. In addition, there was a decrease in the activity of CAT in PG of diabetic and non-diabetic animals after laser irradiation. According to the results of the present study, low-power laser irradiation can affect the enzymatic antioxidant system of salivary glands of streptozotocin-induced diabetic rats.

Sialic acid reduction in the saliva of streptozotocin induced diabetic rats

OBJECTIVE

Diabetes causes changes in the salivary glands and in the composition of saliva, as well as symptoms such as dry mouth and hyposalivation. Therefore, this study aimed at investigating changes in salivary secretion and composition, in response to parasympathetic stimuli, in diabetic rats induced with streptozotocin.

DESIGN

Diabetes was induced by a single intraperitoneal injection of streptozotocin. Thirty days after diabetes induction, the animals were anaesthetized and salivation was stimulated by an intraperitoneal injection of Pilocarpine (0.6mg/kg body weight) dissolved in distilled water. Saliva was collected for 40min and immediately stored at -80°C until analysis. The salivary flow rate, amount of total protein, amylase and peroxidase activities, and free and total sialic acid contents were measured.

RESULTS

Salivary flow rate was reduced in the diabetic group (p<0.05). Moreover, increases in total protein amount and in amylase and peroxidase activities were observed in diabetic animals. No difference was observed for free sialic acid content between groups. On the other hand, a significantly decrease in the total sialic acid content was observed in the diabetic group (p<0.05).

CONCLUSIONS

Our findings suggest that a decrease in sialic acid in the saliva of diabetic animals can be related to xerostomia reported by diabetic patients. However, further clinical trials are needed to verify if the decrease in sialic acid also occurs in human saliva.