Effects of hippocampal lesioning on experimental periodontitis in Wistar rats

The hippocampus, which is a brain structure involved in learning and memory processes, plays a key role in the feedback regulation of the hypothalamic‐pituitary‐adrenal (HPA) axis and autonomic sympathetic nervous system, and the subsequent secretion of immuno‐modulatory hormones in response to pathogenic microorganisms. Dysregulation of these brain‐neuroendocrine‐immune regulatory networks, which act in concert to maintain homeostasis, is found to be of critical importance to the host defence against pathogens, as well as susceptibility to diseases, including periodontal disease. The present study was designed to determine the effects of hippocampal lesioning on the progression of periodontitis. Experimental ligature‐induced periodontitis was induced in 16 Wistar rats, which were bilaterally lesioned in their hippocampal region with an aspiration technique that is well documented to impair learning and memory, as well as in 15 sham‐operated control rats. The disease progression was evaluated radiographically and histometrically. The results revealed that the hippocampal lesioned rats developed significantly more destruction of the periodontium than did the sham‐operated controls. This finding supports recent studies that indicate that inappropriate brain‐neuroendocrine regulation of inflammatory responses to infectious agents may play an important role in disease susceptibility and progression.