Salivary gland dysfunction is a common complication of diabetes. Decreased saliva production and changes in saliva composition may cause oral diseases. Reactive oxygen species (ROS) generation in the salivary glands results in the loss of acinar cells and decreased saliva secretion. Glucagon-like peptide 1 (GLP-1) is the incretin hormone that regulates blood glucose level and can suppress ROS production and inflammation through its antioxidant effects. Dipeptidyl peptidase-4 (DPP-4) is an enzyme that breaks down GLP-1. In this study, we evaluated the pathological role of DPP-4 and GLP-1 on salivary gland dysfunction in type 2 diabetic db/db mice. We observed reduced salivary secretion and histopathological alteration of salivary glands in the db/db mice. The increased DPP-4 and decreased GLP-1 levels in the salivary glands were also detected in the db/db mice. Furthermore, the db/db mice had increased apoptosis and oxidative injury in salivary glands. There was an accumulation of advanced glycation end products and mucus in the salivary glands of the db/db mice. In conclusion, these results showed the possible involvement of DPP-4 and GLP-1, leading to increased ROS-induced apoptosis in diabetes-related salivary gland dysfunction. DPP-4 and GLP-1 may be a pharmacological target for patients with diabetes-related salivary gland dysfunction.

Declined salivary gland function is commonly observed in patients with diabetes. Advanced glycation end products (AGEs) are believed to contribute to the pathogenesis of diabetes-induces hypofunction of the salivary glands. Polydatin (resveratrol-3-O-β-mono-D-glucoside) is a polyphenol that can be easily accessed from peanut, grape, and red wines. Although polydatin is known to have anti-glycation, anti-oxidation, and anti-inflammation effects, its effect in the salivary gland is not known. In the present study, we evaluated the AGEs burden in the salivary gland in streptozotocin (STZ)-induced diabetic rats and the protective effect of polydatin on diabetes-related salivary hypofunction. Polydatin (50 and 100 mg/kg/day) was orally administered in the STZ-induced diabetic rats for 4 weeks. The results showed that the salivary flow rate of the STZ-induced diabetic rats was reduced compared with that in the normoglycemic control rats. The circulating AGEs in serum and secreted AGEs in saliva increased in the STZ-induced diabetic rats. The reactive oxygen specises (ROS) were highly generated in the salivary gland in these diabetic rats. The salivary gland from the diabetic rats showed increased acinar cell apoptosis compared to normoglycemic control mice. However, polydatin suppressed all of these diabetes-related salivary changes. Overall, polydatin could provide a beneficial option for diabetes-related salivary hypofunction.

Cytoplasmic male sterility (CMS) and fertility restoration have been utilized as valuable tools for F_1-hybrid seed production in many crops despite laborious breeding processes. Molecular markers for the selection of CMS-related genes help reduce the expenses and breeding times. A previously reported genomic region containing the Ppr-B gene, which is responsible for restoration of fertility and corresponds to the Rfo locus, was used to develop gene-based or so-called "functional" markers for allelic selection of the restorer-of-fertility gene (Rfo) in F_1-hybrid breeding of radish (Raphanus sativus L.) Polymorphic sequences among Rfo alleles of diverse breeding lines of radish were examined by sequencing the Ppr-B alleles. However, presence of Ppr-B homolog, designated as Ppr-D, interferes on specific PCR amplification of Ppr-B in certain breeding lines. The organization of Ppr-D, resolved by genome walking, revealed extended homology with Ppr-B even in the promoter region. Interestingly, PCR amplification of Ppr-D was repeatedly unsuccessful in certain breeding lines implying the lack of Ppr-D in these radishes. Ppr-B could only be successfully amplified for analysis through designing primers based on the sequences unique to Ppr-B that exclude interference from Ppr-D gene. Four variants of Rfo alleles were identified from 20 breeding lines. A combination of three molecular markers was developed in order to genotype the Rfo locus based on polymorphisms among four different variants. These markers will be useful in facilitating F_1-hybrid cultivar development in radish.