Assessment of the final steps of insulin signaling, inflammatory pathway, oxidative stress, epigenetic mechanism by DNA methylation and GLUT4 expression in the gastrocnemius muscle of adult rats, offspring of rats with apical periodontitis

Author(s)

Thais Veronica Saori Tsosura

• Document type: Doctoral Thesis
• Press: Araçatuba. 2023-04-10.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Odontologia. Araçatuba
• Defense date: 2023-04-05
• Advisor: Doris Hissako Matsushita

Abstract

Fetal programming suggests that adverse stimuli when applied during early fetal development may alter metabolism of offspring, increasing the risk of disease in adulthood. DNA methylation is one of the epigenetic mechanisms involved in this programming and regulates gene expression. Previous studies have shown that maternal apical periodontitis (AP) in rats promotes in their adult offspring: insulin resistance (IR), alteration in the initial steps of the insulin signaling (IS) in the gastrocnemius muscle (GM) and increase in plasma concentration of tumor necrosis factor-α (TNF-α). TNF-α can activate nuclear transcription factor kappa B (NF-kB) thus decreasing gene expression of the GLUT4 glucose transporter. In this context, more studies are needed to investigate whether changes in IS observed in adult rats, offspring of rats with AP are also present in the continuity of the insulin cascade. In addition, since oxidative stress has been implicated as a contributing factor for both the onset and progression of diabetes, it is essential to verify the degree of tissue oxidative stress in this adult offspring. Therefore, the aims of this study were to evaluate IR, oxidative stress, final steps of IS and inflammatory pathway in the GM of adult rats, offspring of rats with AP. For this purpose, 21 female Wistar rats (2 months of age) were distributed into three groups: 1) control rats (CN); 2) group with one AP induced in the upper right first molar (1AP); 3) group with four APs induced in the first and second upper and lower right molars (4AP). AP was induced using a surgical round bur measuring 0.1 mm in diameter. After 30 days of pulp exposure, female rats of all groups were placed for mating. Pregnant rats were separated into individual cages. When the male offspring of all rats reached 75 days of age, the following plasma analyzes were performed: 1) glycemia; 2) insulinemia; 3) IR. Furthermore, the following analyzes were performed in the GM: 1) Akt serine/threonine phosphorylation status, after insulin stimulation; 2) GLUT4 content; 3) degree of DNA methylation in the proximal promoter region of the GLUT4 gene; 4) GLUT4 and TNF- 13 α gene expression; 5) TNF-α and PGC-1α content; 6) p50 and p65 subunits of NF-kB phosphorylation status; 7) oxidative stress (superoxide dismutase – SOD and thiobarbiturate reactive species – TBARS). Statistical analyzes were performed by analysis of variance, followed by the Tukey test. The level of significance adopted was 5%. Results showed that maternal AP (both 1 infection focus and 4 infection focus) promoted hyperinsulinemia, IR and decrease in SOD antioxidant activity and TBARS concentration in the GM of their adult offspring. However, only maternal AP in four teeth promoted an increase in body weight, food intake and p50 and p65 subunits of NF-kB phosphorylation status in the GM of adult offspring. Furthermore, there was a decrease in Akt serine and threonine phosphorylation status (after insulin stimulation) and in gene expression and protein content of GLUT4 in the GM in adult offspring of rats with 4APs. Maternal AP did not change fasting glycemia, PGC-1α content, degree of DNA methylation in the proximal promoter region of GLUT4, gene expression and protein content of TNF-α in the GM of adult offspring. These results demonstrate that maternal AP is associated with IR and promotes important alterations in IS and inflammation pathways in adult offspring. This reinforces the importance of maternal oral health on the overall health of offspring. (AU)

• FAPESP's process: 19/04182-2 - Assessment of the final steps of insulin signaling, inflammatory pathway, oxidative stress, epigenetic mechanism by DNA methylation and GLUT4 expression in the gastrocnemius muscle of adult rats, offspring of rats with Apical Periodontitis
• Grantee: Thaís Verônica Saori Tsosura
• Support Opportunities: Scholarships in Brazil - Doctorate