Effects of Experimental Periodontitis and Periodontal Treatment on Alzheimer-Like Pathology in Rats

Abstract

Objective This study investigated the effects of periodontitis (P) and non-surgical periodontal therapy (NSPT) on behavior, neurodegeneration, and neuroinflammation in rats with Alzheimer's disease (AD)-like pathology. Methods AD-like pathology was induced in rats (n = 28) using STZ neurodegeneration model. Periodontitis was experimentally induced (n = 32), and half of which received NSPT with Chlorhexidine (CHX) gel. Behavioral assessment included the passive avoidance task (PA) and Morris water maze (MWM). Levels of NLRP3, phosphorylated tau (p-tau), and tau in the hippocampus, cerebrospinal fluid (CSF), and serum were measured by ELISA, while BACE1, IL1 beta, iNOS, and NF-kappa beta proteins were assessed by Western blotting. Results Rats in the AD and AD + P groups performed worse in behavioral tests compared to controls (p < 0.05), whereas the NSPT group showed similar performance to controls (p > 0.05). CSF p-tau levels were comparable between AD and AD + P groups, but the hippocampal p-tau/tau ratio was significantly higher in the AD + P group (p < 0.05). BACE1 levels were similar in P and AD groups. NLRP3 and iNOS levels did not show significant differences across groups. Notably, the NSPT group exhibited reduced NF-kappa beta levels (p < 0.05). Conclusions Periodontitis may exacerbate AD-like molecular pathology, particularly by promoting tau hyperphosphorylation, while NSPT appears to mitigate disease progression and improve behavioral outcomes.