Diazepam reverses the alveolar bone loss and hippocampal interleukin‐1beta and interleukin‐6 enhanced by conditioned fear stress in ligature‐induced periodontal disease in rats

Abstract

Stress and anxiety have been associated with chronic periodontitis, but few studies examining the effects of psychotropic drugs on periodontal health have been performed. Therefore, we aimed to investigate the effects of diazepam on the progression of periodontitis in chronically stressed rats. Fourteen Wistar rats were submitted to ligature-induced periodontal disease and were divided into four groups . Two groups were not stressed, whereas two groups were submitted to a conditioned fear stress paradigm for 38 d. Daily diazepam treatment (2 mg/kg, orally) was administered to one unstressed group and to one group submitted to a conditioned fear stress paradigm from day 2 to the day 39, at which point the rats were submitted to an open field test and were killed on day 40. Brains and mandibles were removed for histological and immunohistochemical analyses. Animals exposed to conditioned fear stress presented an increase in freezing behavior, a decrease in locomotor activity, enhanced alveolar bone loss and higher levels of hippocampal interleukin-1beta (IL-1β) and interleukin-6 (IL-6), compared with the control group. Diazepam, at the dose used in the current study, had no effect on freezing behavior but reversed the decrease in locomotor activity provoked by stress. Additionally, the treatment reduced the levels of hippocampal IL-1β and IL-6 and alveolar bone loss in Wistar rats. Neither conditioned fear stress nor diazepam treatment had an effect on periodontal IL-1β or IL-6 levels in animals. Our results suggest that diazepam treatment reduces bone loss in rats submitted to conditioned fear stress. In addition, diazepam treatment led to decreased IL-1β and IL-6 levels in the hippocampus.