Effects of diabetes and insulin on alpha-amylase messenger RNA levels in rat parotid glands

Association of salivary levels of immunoglobulin-a and amylase with oral-dental manifestations in patients with controlled and non-controlled type 2 diabetes

Background

Oral health is related to general health and one of the most prevalent chronic diseases is diabetes mellitus. Diabetes can have adverse effects on oral health and vice versa. Saliva analysis can be used as a non-invasive method to obtain information about diseases status like diabetes. The aim of present study was to evaluate the salivary immunoglobulin-A (s-IgA) and salivary amylase levels and their associations with oral-dental manifestations in patients with controlled and non-controlled type 2 diabetes.

Methods

This case-control study was carried out on 90 subjects who referred to the Diabetes Center of Shahid Bahonar Hospital, Kerman University of Medical Sciences, Kerman, Iran. Participants were divided into three groups: 1) uncontrolled diabetic patients (n = 30); 2) controlled diabetic patients (n = 30); and 3) healthy individuals (n = 30). Unstimulated salivary levels of I-A and amylase were measured. All participants underwent a dental and periodontal examination to explore the oral and dental manifestations. T-test, chi-square and ANOVA tests were used for data analysis in SPSS 18.

Results

Significant higher level of s-IgA was found in uncontrolled diabetic patients compared to controlled diabetic (P ≤ 0.0001) and the control group (P = 0.004). Moreover, the mean levels of s-amylase in uncontrolled patients was significantly higher compared to controlled diabetic (P = 0.01) and the control group (P ≤ 0.0001). Uncontrolled diabetic patients with oral candidiasis, erythematous candidiasis, abscesses, or xerostomia had higher s-IgA levels compared to the controlled diabetic participants. Moreover, uncontrolled diabetic patients with oral candidiasis or erythematous candidiasis showed a significant higher levels of s-amylase compared to controlled diabetic patients. Also, significant positive correlations were found between s-IgA and DMFT and s-IgA and PDI (r = 0.444, P = 0.014 and r = 0.386, P = 0.035, respectively).

Conclusion

In conclusion, higher s-amylase and s-IgA concentrations may reflect oral-dental manifestations in T2DM. Moreover, the current findings suggest that s-amylase and s-IgA may serve as a complementary and alternative fluid in screening for diabetes mellitus.

Ixeris dentata Extract Increases Salivary Secretion through the Regulation of Endoplasmic Reticulum Stress in a Diabetes-Induced Xerostomia Rat Model

This study aimed to investigate the molecular mechanism of diabetes mellitus (DM)-induced dry mouth and an application of natural products from Ixeris dentata (IXD), a recently suggested regulator of amylase secretion in salivary cells. Vehicle-treated or diabetic rats were orally treated with either water or an IXD extract for 10 days to observe the effect on salivary flow. We found that the IXD extract increased aquaporin 5 (AQP5) and alpha-amylase protein expression in the submandibular gland along with salivary flow rate. Similarly, the IXD extract and its purified compound increased amylase secretion in high glucose-exposed human salivary gland cells. Furthermore, increased endoplasmic reticulum stress response in the submandibular gland of diabetic rats was inhibited by treatment with the IXD extract, suggesting that IXD extract treatment improves the ER environment by increasing the protein folding capacity. Thus, pharmacological treatment with the IXD extract is suggested to relieve DM-induced dry mouth symptoms.

Red ginseng powder fermented with probiotics exerts antidiabetic effects in the streptozotocin-induced mouse diabetes model

CONTEXT

Red ginseng (heat-processed Panax ginseng) is a well-known alternative medicine with pharmacological antidiabetic activity. It exerts pharmacological effects through the transformation of saponin into metabolites by the intestinal microbiota. Given that intestinal conditions and intestinal microflora vary among individuals, the pharmacological effects of orally administered red ginseng likely may vary among individuals.

OBJECTIVE

To overcome this variation and produce homogeneously effective red ginseng, we evaluated the antidiabetic effects of probiotic-fermented red ginseng in a mouse model.

MATERIALS AND METHODS

The antidiabetic efficacy of orally administered probiotic-fermented red ginseng was assessed in ICR mice after induction of diabetes using streptozotocin (170 mg/kg body weight). Samples were given orally for 8 weeks, and indicators involved in diabetic disorders such as body weight change, water intake, blood glucose, glucose tolerance and various biochemical parameters were determined.

RESULTS

Oral administration of probiotic-fermented red ginseng significantly decreased the level of blood glucose of about 62.5% in the fasting state and induced a significant increase in glucose tolerance of about 10.2% compared to the control diabetic mice. Additionally, various indicators of diabetes and biochemical data (e.g., blood glycosylated haemoglobin level, serum concentrations of insulin, and α-amylase activity) showed a significant improvement in the diabetic conditions of the mice treated with probiotic-fermented red ginseng in comparison with those of control diabetic mice.

DISCUSSION AND CONCLUSION

Our results demonstrate the antidiabetic effects of probiotic-fermented red ginseng in the streptozotocin-induced mouse diabetes model and suggest that probiotic-fermented red ginseng may be a uniformly effective red ginseng product.

Changes in the salivary protein profile of morbidly obese women either previously subjected to bariatric surgery or not

Saliva is a non-invasive source of biomarkers useful in the study of physiological mechanisms. Moreover, this fluid has diverse functions, among which food perception and ingestion, making it particularly suitable for the study of obesity. The aims of this study were to assess changes in salivary proteome among morbidly obese women, with a view to provide information about mechanisms potentially related to the development of obesity, and to evaluate whether these changes persist after weight loss. Mixed saliva samples from morbidly obese women (N = 18) who had been either subjected (group O-BS) or not (group O) to bariatric surgery and women with normal weight (N = 14; group C) were compared for protein profiles, alpha-amylase abundance and enzymatic activity, and carbonic anhydrase (CA) VI abundance. Differences in salivary obese profiles were observed for 23 different spots. Zinc-alpha-2 glycoprotein-containing spots showed higher abundance in group O only, whereas cystatin S-containing spots presented higher abundance in the two groups of obese subjects. Most of the spots identified as salivary amylase were present at lower levels in group O-BS. With regard to the amylase enzymatic activity, increases were observed for group O and decreases for group O-BS. One interesting finding was the high correlation between levels of CA VI and body mass index in group O, which was not observed for groups O-BS or C. The differences between groups, mainly regarding salivary proteins involved in taste sensitivity and metabolism, point to the potential of using saliva in the study of obesity development.

Evaluation of Salivary Profile among Adult Type 2 Diabetes Mellitus Patients in South India

BACKGROUND

A lack of consensus on the possible association between diabetes and salivary dysfunction motivated us to conduct this investigation on the salivary parameters in diabetic and non diabetic subjects. This could also make the use of saliva as an alternative to that of blood in the diagnosis/monitoring of diabetes mellitus.

OBJECTIVES

To compare the salivary flow rates and the salivary physical and biochemical parameters of diabetic (D) and non diabetic (ND) subjects.

MATERIAL AND METHODS

The participants in this study included 30 non diabetic subjects and 30 diabetic volunteers who had Type 2 Diabetes mellitus for a minimum of 2 years. Unstimulated whole saliva was collected in the fasting state. Salivary pH, flow rate and organic and inorganic constituents were evaluated. Data which was collected was statistically analysed and interpreted.

RESULTS

Salivary pH (ND=7.09±0.29, D=6.69±0.35), flow rate (ND=0.67±0.07, D=0.46±0.02) and salivary amylase (ND=92.51±13.74, D=19.20±1.8) were significantly lower in diabetics. They had significantly higher levels of salivary glucose (ND=4.33 ± 0.29, D=17.31±2.05), total proteins (ND=424.46±237.34, D=877.29±603.84), sodium (ND=4.31±0.65, D=14.42±1.83) and potassium (ND=20.84±0.71, D=25.95±1.56) and lower levels of calcium (ND=6.39±0.5, D=4.22±0.12) in comparison to those in the non-diabetic group.

CONCLUSION

Significant variations were observed in salivary physical and biochemical parameters between diabetics and non diabetics. Evaluation of salivary parameters can be a cost effective and a non invasive alternative for screening, diagnosis and monitoring of diabetes, to blood.

Protein expression in salivary glands of rats with streptozotocin diabetes

Diabetes mellitus (DM) is a widespread disease with high morbidity and health care costs. An experimental animal model was employed, using morphological and biochemical methods, to investigate the effects of DM on the expression and compartmentation of salivary gland proteins. The distribution of proline-rich proteins (PRP), submandibular mucin (Muc10) and the regulatory (RI and RII) subunits of cyclic AMP-dependent protein kinase type I and type II was determined in the parotid and submandibular (SMG) glands of rats treated with streptozotocin. Quantitative immunocytochemistry of secretory granules in diabetic glands revealed decreases of 30% for PRP in both the parotid and SMG, and a 40% decrease in Muc10 in the SMG. Immunogold labelling showed that RII decreased in nuclei and the cytoplasm in diabetic acinar cells while labelling of secretory granules was similar in control and diabetic parotid. Electrophoresis and Western blotting of tissue extracts of two secretory proteins showed that the response to DM and insulin treatment was gland specific: PRP showed little change in the SMG, but decreased in the parotid in DM and was partially restored after insulin treatment. Photoaffinity labelling showed only RI present in the SMG and mainly RII in the parotid. The results of this and previous studies demonstrating highly specific changes in salivary protein expression indicate that the oral environment is significantly altered by DM, and that oral tissues and their function can be compromised. These findings may provide a basis for future studies to develop tests using saliva for diabetic status or progression in humans.

A comparison of ghrelin, glucose, alpha-amylase and protein levels in saliva from diabetics

During the past decade, many salivary parameters have been used to characterize disease states. Ghrelin (GAH) is recently-discovered peptide hormone secreted mainly from the stomach but also produced in a number of other tissues including salivary glands. The aim of this work was to examine the relationship between active (aGAH) and inactive (dGAH) ghrelin in the saliva and other salivary parameters in type II diabetic patients and healthy controls. Salivary parameters were assessed in a single measurement of unstimulated whole saliva from 20 obese and 20 non-obese type II diabetes patients, and in 22 healthy controls. Total protein and alpha-amylase were determined by colorimetric methods, and glucose by the glucose-oxidase method. Saliva aGAH and dGAH levels were measured using a commercial radioimmunoassay (RIA) kit. Salivary concentrations of aGAH and dGAH ghrelin were more markedly decreased in obese diabetic subjects than in the two other groups. Glucose and alpha-amylase levels were higher in diabetic subjects than in controls. Furthermore, there were correlations between GAH levels and BMI, and between GAH and blood pressure. However, there was no marked variability in saliva flow rates among the groups. These results indicate that measurement of salivary GAH and its relationship to other salivary parameters might help to provide insight into the role of ghrelin in diabetes.

Streptozotocin-induced type 1 diabetes mellitus alters the morphology, secretory function and acyl lipid contents in the isolated rat parotid salivary gland

Diabetes mellitus (DM) is associated with numerous conditions including hypo-secretion of digestive enzymes. This study investigated the morphology, secretory function (alpha-amylase release) and acyl lipid contents in the isolated parotid gland of STZ-induced diabetic and age-matched control rats in order to provide insights into diabetes-induced salivary insufficiency. The techniques employed included light microscopy, colourimetric and gas chromatography (GC) analysis, respectively. Diabetes mellitus was induced in adult male Wistar rats by a single intraperitoneal (IP) injection of streptozotocin (STZ) (60 mg per kg body weight). Control animals were injected with a similar volume of citrate buffer. The animals were tested for DM 4 days after STZ injection and 2 months later when they were humanely killed for the experiment. The morphological results showed diabetic parotid glands to be extensively infiltrated with lipid droplets of various magnitudes, whereas glands from control animals display normal structure with the absence of lipid droplets. The analysis of parotid secretory function revealed a significant (p < 0.05) dose-dependent decrease in alpha-amylase release in response to noradrenaline (NA) in STZ-treated glands when compared to age-match control parotid glands. Furthermore, the levels of acyl lipids (16:0, 16:1, 18:0 and 18:1) in diabetic parotid glands was significantly (p < 0.01) reduced compared to control glands, along with a reduced ratio of 16:1/16:0. The results indicate DM can elicit changes in the morphology, secretory function and acyl fatty acid quantity in the isolated rat parotid gland.

Possible role of gangliosides in salivary gland complications of diabetes

Gangliosides have previously been considered to be possible antigenic sites in Type 1 diabetes. Lymphocytic infiltration of Langerhans islands is the pathologic hallmark of autoimmune diabetes and may also be observed in salivary glands in experimental diabetes. Diabetic complications of parotid and submaxillary glands may therefore be related with an autoimmune process against sialoglycoconjugates of salivary gland tissue.

Salivary EGF levels reduced in diabetic patients

Oral problems such as periodontitis are recognized major complications associated with diabetes. Salivary derived growth factors, including epidermal growth factor (EGF), are thought to play a role in helping maintain levels of oral health, promoting wound healing, and maintaining mucosal integrity. In the present study, salivary levels of EGF in diabetic vs. healthy control patients was evaluated. Twenty-one diabetic patients participated in this study. Age, race, sex and smoking histories were matched with 21 systematically healthy nondiabetic patients. Three milliliters of unstimulated resting whole saliva was collected from each patient at 6 h intervals up to 42 h and whole saliva protein concentrations were determined for each sample. EGF concentrations for each sample were quantitated spectrophometrically utilizing an immunoassay. Diabetic patients had greater salivary protein concentrations over 42 h of collection with a mean of 1.502+/-0.09 vs. 1.242+/-0.05 mg/ml for healthy control patients. The EGF concentration was significantly lower (p<0.05) for the diabetic patients compared to control patients, whether expressed relative to 1 ml volume of saliva (873.43+/-106.5 vs. 1101.09+/-116.8 pg/ml) or 1 mg whole saliva protein (629.18+/-92.6 vs. 931.20+/-124.6 pg/mg saliva protein). This study suggests that reduced levels of salivary EGF in diabetic patients may contribute to the development of oral and systemic complications of diabetes, which may have future clinical applications.

Effects of glycemic control on saliva flow rates and protein composition in non-insulin-dependent diabetes mellitus

OBJECTIVE

The objective of this study was to determine whether improvements in the level of diabetic control in a group of subjects with poorly controlled non-insulin-dependent diabetes mellitus influence salivary output and composition.

STUDY DESIGN

Repeated whole unstimulated and stimulated parotid saliva samples were collected from diabetic patients attending an outpatient diabetes education program and a matched nondiabetic control group. Saliva was analyzed for flow rates, parotid protein concentration and composition, and amylase activity. Subjective responses to questions about salivary hypofunction were tested.

RESULTS

There were no significant differences in whole unstimulated and stimulated parotid flow rates or stimulated parotid protein concentration and composition between diabetics and the control group. Amylase activity was higher in diabetics and decreased with improved glycemic control. Subjects reporting taste alterations had higher mean blood glucose levels than subjects with normal taste sensation.

CONCLUSIONS

Poorly controlled non-insulin-dependent diabetes mellitus has no influence on saliva output, although amylase activity may be elevated, and there may be taste alterations.

Saliva and growth factors: the fountain of youth resides in us all

The predominant focus of research dealing with saliva revolves around the role in the maintenance of oral health through a number of physiological and biological properties of constituent proteins. An ever-expanding literature exists indicating that the salivary glands additionally synthesize, and secrete into saliva, a wide range of growth factors. Animal studies with epidermal growth factor have provided evidence for a role in both oral and systemic health, through the promotion of wound healing rates. Thus, the ability to manipulate their rates of synthesis and absorption from saliva holds the potential to enhance tissue regeneration and homeostasis.

Detection of insulin and insulin-like growth factors I and II in saliva and potential synthesis in the salivary glands of mice. Effects of type 1 diabetes mellitus

The salivary glands of mammals synthesize and secrete a number of peptide growth factors that play important roles in cell/tissue homeostasis and embryonic development. Using a radioimmunoassay, insulin, insulin-like growth factor-I (IGF-I) and insulin-like growth factor-II (IGF-II) were detected in saliva from mice. Unlike epidermal growth factor (EGF), there was no sexual dimorphism in the concentrations of the insulin growth factor family. Immunohistochemical localization of IGF-I and IGF-II was confined to the duct cells of both the parotid and the submandibular glands. Reverse transcriptase-polymerase chain reaction amplification of total RNA from parotid and submandibular glands confirmed the presence of all three hormone/growth factor mRNAs in both glands. The levels of insulin and IGF-I were higher in saliva from an animal model for autoimmune type 1 diabetes, the non-obese diabetic (NOD) mouse, than in a second inbred strain, BALB/c. In contrast, the IGF-II levels were decreased relative to the BALB/c strain. With the onset of diabetes in NOD mice, insulin levels declined, while IGF-I and IGF-II levels showed trends toward lower levels of these growth factors when compared with non-diabetic animals. These changes were reflected in the concentrations from parotid and submandibular gland cell lysates.

Structural and functional changes in salivary glands during aging

Various salivary glands in senescent humans and other animals have been examined extensively to characterize the structural and functional changes that occur during aging. Although a wide range of different structural changes, involving both the parenchymal and stromal tissues, have been described, it is unclear how any of these changes affects the function of the salivary glands. One major change in structure is the reduction in the volume of acini with a concomitant increase in the ductal volume. Despite this loss of functional acini, the salivary output and the contents seem to be unaltered, or minimally altered, due to aging. One consistent change observed in many salivary glands of aged animals is the decline in the rate of synthesis of proteins and their messenger RNA (mRNA). However, the salivary acinar cells from aged animals can synthesize secretory proteins at an elevated rate just as effectively as those from their younger counterparts in response to external stimuli, which are known to enhance the rate of protein synthesis. Thus, it appears that the salivary acinar cells, which remain structurally intact during aging, seem to retain their functional efficiency. Furthermore, these acinar cells, although reduced in number, are sufficient in quantity to carry out most of the salivary gland functions.

The effects of streptozotocin diabetes on salivary-mediated bacterial aggregation and adherence

Diabetic rats are known to have an increased susceptibility to dental caries and major alterations in parotid salivary composition. Salivary proteins play an important part in oral health maintenance; thus specific changes in salivary protein composition in diabetic animals might alter the ecological balance in favour of cariogenic bacteria, and toward the initiation and progression of the disease process. The ability of whole, parotid and submandibular salivas from control and streptozotocin-diabetic rats to mediate the aggregation and adherence to hydroxyapatite of mutans streptococci was examined. Salivary-mediated bacterial aggregating activity was significantly reduced in whole and parotid salivas from diabetic rats, but bacterial adherence to hydroxyapatite was unaffected. The aggregating and adherence activities of rat whole saliva were derived mainly from parotid saliva, which contains predominantly low molecular-weight proteins and glycoproteins (< 200 kDa), but rat parotid saliva was capable of interacting with the bacterial receptor for the high molecular-weight aggregating factor in human saliva. SDS-PAGE of parotid saliva revealed that a number of proteins, including the basic and acid proline-rich proteins, were altered in the salivas of diabetic animals. After incubation with either Streptococcus mutans or hydroxyapatite several protein bands were depleted, and thus a variety of proteins and glycoproteins may be responsible for the adherence and aggregating activity of rat parotid saliva.

Effects of surgical ovariectomy on rat salivary gland function

Studies sought to determine whether there are specific changes in salivary gland protein synthesis and secretion in response to hormone deficiency caused by ovariectomy of female rats. After 50 days, the wet weights of the parotid and submandibular glands did not change with hormone loss while that of the sublingual gland increased by 26% when compared to sham-operated controls. Amylase activity in the parotid declined, as did the level of enzyme activity present in saliva. The amount of the acidic proline-rich protein in the parotid was not altered after ovariectomy when compared to control sham-operated animals, using constant quantities of lysate protein. The total of secreted protein per unit volume did not change with ovariectomy. However, sodium dodecylsulphate-polyacrylamide gel electrophoresis of whole saliva showed the loss of a substantial number of proteins, including amylase and the acidic proline-rich proteins, from the experimental group. Epidermal growth factor concentrations were not significantly altered in the submandibular gland, while again showing a decrease in the concentration from saliva in ovariectomized rats.

Functional changes in salivary glands of autoimmune disease-prone NOD mice

Lymphocytic infiltration of the salivary glands in autoimmune diseases results in the human condition known as xerostomia. To date, an animal model for the autoimmune development of salivary gland dysfunction has yet to be described. With the autoimmune diabetes-prone nonobese diabetic (NOD) mouse strain, salivary flow rates and total saliva protein concentration in both male and female mice showed a progressive decline in the nondiabetic and diabetic states. Submandibular gland weight decreased from control mice with the progression to onset of diabetes in both sexes, whereas the weight of the parotid gland remained unchanged. The level of saliva amylase activity, when measured relative to unit volume, decreased in nondiabetic males but increased upon onset of diabetes to control values. When expressed relative to protein concentration in saliva, amylase activity was depressed for both sets of NOD mice but was higher upon diabetes onset than in the nondiabetic animals. In females a similar pattern was observed except that amylase activity expressed relative to unit volume was not significantly depressed in either set of NOD mice. The same observations were made for glandular amylase activity. The level of epidermal growth factor (a product of the ductal cells of the submandibular gland) was reduced over 500- and 18-fold for male and female diabetic mice, respectively. Sodium dodecyl sulfate polyacrylamide gels of total saliva showed changes in mobility as well as concentration of several proteins in the NOD mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of streptozotocin diabetes on amylase release and cAMP accumulation in rat parotid acinar cells

Rat parotid responses to sympathetic nerve stimulation in vivo are impaired 2-4 weeks after the induction of streptozotocin diabetes. In this study, the effects of experimental diabetes of similar duration and severity on noradrenaline-stimulated amylase release and cAMP accumulation were examined in vitro. Amylase levels were significantly lower in acinar cells isolated from diabetic animals than in controls, and cellular amylase increased after treatment of the diabetic animals with either thyroxine (T4) or insulin. Diabetes and T4 had no apparent affect on amylase release measured as a percentage of the total. In contrast, giving insulin resulted in a significant reduction in maximal secretion (20.4 +/- 2.4% compared with 43.6 +/- 7.6%). Similar results were observed when amylase release was stimulated with forskolin. Basal cAMP levels were unaffected by diabetes or T4 (7.8 +/- 2.3 pmol/mg protein), but stimulated cAMP levels were significantly greater in diabetic acinar cells than in controls. Insulin reversed the effects of diabetes on cAMP accumulation, whereas T4 had no effect. Thus, diabetes (2-4 weeks) and insulin in vivo appear to have paradoxical effects on parotid amylase release and cAMP accumulation in vitro. Further, the effects of diabetes appear to be unrelated to thyroid status.

Amylase mRNA synthesis and ageing in rat parotid glands following isoproterenol-stimulated secretion

In the parotid, as well as in other exocrine glands, secretory protein synthesis declines with age. However, whether this decline in the steady-state rate of protein synthesis reflects the reduced digestive activity of the animal or actual cellular alterations that affect synthesis is unknown. Here the ability to synthesize amylase and its mRNA during the period of enhanced protein synthesis following secretion induced by isoproterenol was compared in acinar cells of 2-and 24-month-old rats. In unstimulated glands, rates of synthesis of total protein and amylase, as well as amounts of amylase mRNA, were significantly less in the older rats than in their younger counterparts. After stimulation with isoproterenol, which induced the secretion of about 50% of stored proteins, rates of synthesis of total protein, as well as amylase, were increased by about 2.5 x the unstimulated rates in both age groups. However, the amount of amylase mRNA did not increase in parallel with the increase in the rate of amylase protein synthesis in both young and old rats. The molecular size of the mRNA was the same in stimulated and unstimulated glands of both age groups. Thus, it appears that parotid acinar cells from old rats can be stimulated to synthesize secretory proteins at an increased rate. It remains to be determined what causes the reduced rate of protein synthesis in unstimulated glands in old rats.

Effects of age on diabetes- and insulin-induced changes in pancreatic levels of alpha-amylase and its mRNA

During aging, protein synthesis undergoes decremental changes in many organs and tissues. In the pancreas, as well as in other exocrine glands, the rate of protein synthesis declines with age. However, it is unknown whether this decline is related to intrinsic aging changes which affect the secretory cell function. In this study, we compared the ability of pancreatic acinar cells to synthesize amylase and its messenger RNA (mRNA) in response to insulin treatment of young and old rats rendered diabetic with streptozotocin (STZ). In STZ-induced diabetic rats, amylase protein and its mRNA levels were reduced drastically in the pancreas of young and old groups. Injections of these diabetic rats with insulin increased pancreatic amylase mRNA contents significantly in both young and old rats. Insulin also increased proportions of amylase protein synthesis in the pancreas of both age groups. These results indicate that the pancreatic cells remain effective during aging in their transcriptional activity for functional amylase mRNA in response to an exogenous stimulus of insulin.