Local Histamine Administration Prevents Periodontitis Induced Hyposialia in Rats

Objectives: To determine the effect of local histamine (H) administration over inflammatory mediators and salivary secretion in rats with experimental periodontitis (EP).

Methods: 40 male Wistar rats weighting between 200-250 gr were divided into 4 groups: Control (C), H, EP, EP+H. EP was induced by placing a cotton thread ligature around lower first molars over 14 days. 0.1ml of a histamine gel or its vehicle (C) was applied daily on bucal side of lower first molars. Salivary secretion was determined by stimulation with methacholine 1, 3 y 10 µg/kg, before and after intraglandular injection of histamine 50µg/50 µl. Inflammatory mediators were determined in gums and submandibular gland (SMG). Statistical analysis was assessed by one way ANOVA, followed by Tukey test, for comparisons between groups; and paired Students test for salivary secretion before and after histamine administration. P values <0.05 were considered significant.

Results: EP increased iNOS activity (C: 832,6±157.1nmol NO/min vs EP: 4309±756.4 nmol NO/min; p<0.001) and TNFα levels (C: 29.57±2.31pg vs EP: 45.09±2.85pg ; p<0.001) in gingival tissue, while histamine administration did not have influence on this results. No statistical differences were found on TNFα levels in SMG. EP reduced methacholine induced salivary secretion at 1µg/kg (C: 4±0.2mg vs EP: 1.4±0.68mg; p<0.05), which was not observed at higher concentrations. Histamine treated groups showed increased salivary secretion at all methacholine concentrations than vehicle groups. Intraglandular histamine injection enhanced salivary secretion, but only on vehicle groups. This effect was not observed on histamine treated groups.

Conclusions: Local histamine administration prevents experimental periodontitis induced bone loss and hyposialia, suggesting a preventive effect on reciprocal induction between periodontal damage and hyposalivation.