α-Lipoic Acid Supplementation Was Not Effective in Restoring Salivary Flow Rate and Salivary Glands Redox Equilibrium in the Hyperglycaemic Rats

Background/Aims: The aim of the present study was to investigate whether alpha-lipoic acid (ALA) could reverse/prevent high fat diet (HFD)-induced salivary gland dysfunction and oxidative damage in the salivary glands of rats, and strengthen their antioxidant defense. Methods: The enzymatic and non-enzymatic antioxidants as well as their redox status, oxidative damage products and salivary flow rate were investigated in the parotid (PG) and submandibular (SMG) glands of Wistar rats exposed to a high-fat diet and then supplemented with ALA for a period of 4 weeks. The rats in the study were divided into 4 groups of 10 animals each: C (control), HFD, C + ALA, HFD + ALA. Results: The HFD + ALA group in comparison to the HFD group showed normalization of the activity of antioxidant enzymes to the levels observed in the C group only in the case of the SMG. Additionally, ALA supplementation was more effective in reducing the value of oxidative damage products in the PG compared to the SMG. ALA supplementation in the HFD group was not able to restore the disturbed total antioxidant capacity (TAC) of the salivary glands to the level observed in the C group. In the group of HFD + ALA rats, both unstimulated and stimulated salivation and the protein concentration in the SMG did not differ significantly from the parameters recorded in the group fed with HFD. Conclusion: ALA supplementation by rats fed the HFD diet prevents/reverses oxidative damage in the PG to a greater extent than in the SMG and is unable to completely restore disturbed TAC to the levels seen in C rats. Moreover, we observed that ALA supplementation did not improve the impaired secretory function of the salivary glands. (c) 2022 The Author(s). Published by Cell Physiol Biochem Press GmbH&Co.