Recovery of INS-R and ER-alpha expression in the salivary glands of diabetic mice submitted to hormone replacement therapy

Ixeris dentata and Lactobacillus gasseri Extracts Improve Salivary Secretion Capability in Diabetes-Associated Dry Mouth Rat Model

Dry mouth, hyposalivation, or xerostomia is a significant problem in diabetic patients; however, there has been no way to relieve these symptoms. This study’s aim was to evaluate the effects of Ixeris dentata (IXD) in combination with lactobacillus extract on the salivation rate in diabetes-induced dry mouth, and its mechanism was also investigated. In the streptozotocin (STZ)-induced diabetes model, the dry mouth condition was established as a model. Here, rats were treated with water or IXD through the sublingual spray, and subsequently treated with or without a spray of lactobacillus extract. In diabetes condition, the salivary flow rate, amylase activity, and aquaporin-5 and Na⁺/H⁺ exchanger (NHE-1) expressions were markedly decreased, whereas they were more significantly recovered in the sequential treatment of IXD-lactobacillus extract than in each single treatment. Furthermore, oxidative stress and its related ER stress response were especially regulated in the IXD/lactobacillus extract condition, where the following anti-oxidative enzymes, glutathione assay (GSH: GSSG) ratio, superoxide dismutase (SOD), and glutathione peroxidase (GPx), were involved. This study suggests that the combination of IXD and lactobacillus would be a potential alternative medicine against diabetes-induced hyposalivation and xerostomia.

Larrea divaricata Cav. aqueous extract and nordihydroguariaretic acid modulate oxidative stress in submandibular glands of diabetic rats: a buccal protective in diabetes

Background

Oxidative stress is an imbalance between the levels of reactive oxygen species (ROS), reactive nitrogen species (RNS) and endogenous antioxidants. The aetiology and pathogenesis of several oral diseases are attributed to this process. The antioxidant enzymes secreted in the saliva by submandibular glands maintain oral health through the scavenging of ROS. The objective of this work was to study the capacity of an aqueous extract of L. divaricata (AE), and its majority compound, nordihydroguariaretic acid (NDGA), to modulate the pro-oxidant/antioxidant status in submandibular glands in a model of oxidative stress induced by streptozotocin (STZ) in rats.

Methods

To induce oxidative stress with STZ, a group of animals was treated i.p. with 1 X PBS (control group) and other group was injected i.p. once with STZ (60 mg/kg). Ten days after the treatment, blood samples were taken from the tail vain to determine the glucose levels. Animals with glucose values ≥300 mg/ml were selected.

The submandibular glands of control and STZ treated animals were incubated with either the AE (500 μg/ml) or with NDGA (1.5 μg/ml), and the content of malondialdehyde (MDA), protein carbonyl groups, ROS and RNS, and the activity and expression of peroxidase (Px), superoxide dismutase (SOD) and inducible nitric oxide synthase (iNOS) were assayed.

Results

AE decreased the levels of MDA (^##P < 0.01) and protein carbonyl groups (^#P < 0.05), and modulated the levels of ROS such as hydrogen peroxide (H₂O₂)(^##P < 0.01), superoxide anion (O₂^.-) (^#P < 0.05) and nitric oxide (NO) (^#P < 0.05) in relation to the modulation of Px and iNOS expression. NDGA was found to be involved in these effects.

Conclusions

The antioxidant activity of the AE in the submandibular glands would allow the maintenance of the antioxidant pool to prevent oral oxidative diseases.

Effects of Diabetes on Post-Menopausal Rat Submandibular Glands: A Histopathological and Stereological Examination

OBJECTIVE

The menopause in elderly women is a physiological process where ovarian and uterine cycles end. Diabetes means higher blood glucose level that is a metabolic disease and has an increased incidence. The aim of the study was to examine the single or combined effects of menopause and diabetes that causes pathophysiological processes on submandibular gland on ovariectomy and diabetes induced rat models.

MATERIALS AND METHODS

Sprague Dawley twelve weeks old female (n=24) rats were divided randomly into four groups; Healthy control group (n=6), diabetic group (DM, n=6), ovariectomized group (OVX, n=6), post ovariectomy diabetes induced group (DM+OVX, n=6) individually. Histopathological, histochemical and stereological analyses were done in these groups.

RESULTS

Significant neutrophil cell infiltrations and myoepithelial cell proliferations, granular duct and seromucous acini damages and changes in the content of especially seromucous acini secretion in DM and/or OVX groups and distinctive interstitial and striated duct damages in post ovariectomy diabetes induced group were detected. Alterations ingranular ducts hypertrophic and in seromucous acini atrophic were determined in DM and/or OVX groups.

CONCLUSION

The results revealed the pathophysiological processes that lead to morphological and functional alterations on the cellular level in submandibular glands. The molecular mechanisms related with pathogenesis of diabetes and menopause need further investigation.

Ixeris dentata-induced regulation of amylase synthesis and secretion in glucose-treated human salivary gland cells

The endoplasmic reticulum (ER) is an organelle which controls synthesis of secretory and membrane proteins. Alterations in protein folding capacity, leading to ER stress, can be observed in patients with diabetes and related diseases such as xerostomia. The objectives of this study were to investigate the effects of Ixeris dentata (IXD) extract, which has been used for diabetes treatment, and compounds purified from IXD, 8-epidesacylcynaropicrin-3-O-beta-glucopyranoside (ID-57D), on amylase synthesis and secretion in human salivary gland (HSG) cells exposed to a high concentration of glucose. A high concentration of glucose in the experimental medium of cultured cells can model diabetes in vitro. IXD extracts and ID-57D increased oxidative folding-associated protein expression, including p-IRE-1α, PDI and ERO-1α, with the enhanced oxidative folding pattern seen in HSG cells transiently exposed to a high concentration of glucose. Moreover, the treatments reduced the ER stress response, such as the expression of GRP78, maintaining amylase synthesis and secretion in chronically glucose-exposed HSG cells. This study suggests the potential therapeutic value of IXD extract for the treatment of diabetes or its complications such as xerostomia.

Dipeptidyl peptidase IV inhibitor improves the salivary gland histology of spontaneously diabetic mice

OBJECTIVES

The incretin-based therapy might be effective in patients possessing certain levels of preserved pancreatic beta-cells. However, doubts still exist regarding the efficacy of this atment in the recovery of tissues damaged by type 1 diabetes. Thus, the objective of this study was to evaluate the treatment with MK0431 in salivary glands of spontaneously diabetic mice, focusing mainly on the possible therapeutic and hypoglycaemic effects of this dipeptidyl peptidase IV inhibitor in the recovery of these salivary tissues.

METHODS AND RESULTS

Twenty mice were divided into two groups of 10 animals each: group I (NOD diabetic/untreated) and group II (NOD diabetic MK0431/treated). The group II was treated during 4 weeks with MK0431 mixed in the food. The group I was maintained in the same way without receiving, however, any treatment. Glucose levels were monitored during treatment and salivary glands samples were collected at the end of treatment for the histological examination under both transmitted and polarized light microscopy. High glucose levels were observed in untreated animals, while in animals with treatment, reduction of these levels was observed. Tissue restructuring was also observed in animals submitted to therapy with MK0431, mainly in relation to the attempt to extracellular matrix reorganization.

CONCLUSIONS

According to results, the treatment with this dipeptidyl peptidase IV inhibitor contributed to the general homeostasis of the organism and to the reestablishment of both epithelial and stromal compartments which were damaged by the hyperglycaemic condition, demonstrating that the incretin-based therapy may be an important complementary treatment for the type 1 diabetic condition.

Effects of anti-CD3 monoclonal antibody in salivary glands of spontaneously diabetic mice

BACKGROUND

Diabetes mellitus results in many complications, also compromising the salivary glands. The current treatment for this condition should be a substituting method to exogenous insulin. In this aspect, the immunotherapy has been tested, but, it can be inefficient as an agent for the control of damage caused by diabetes. Thus, the aim of this study was to evaluate the anti-CD3 monoclonal antibody as alternative immunotherapy in the recovery of salivary glands of spontaneously diabetic NOD (nonobese diabetic) mice.

METHODS

NOD mice were divided into two groups of 10 animals: group I (untreated diabetic mice) and group II (anti-CD3-treated diabetic mice). After treatment, the samples of salivary glands were collected for histological examination under both transmitted and polarized light microscopy.

RESULTS

Alterations in tissue architecture; increase in extracellular matrix and presence of inflammatory process were observed in untreated animals. Recovery of the salivary acinar cells occurred in treated animals. The parotid glands demonstrated a smaller amount of collagen fibers and were not observed severe inflammatory processes.

CONCLUSION

These results indicate that immunotherapy contributed to reestablishment of tissue damaged by the hyperglycemic condition, demonstrating that the immunomodulation plays an important role in the recovery of salivary glands.