NEUROGENIC COMPONENT IN LIGATURE-INDUCED PERIODONTITIS IN THE RAT

Effect of ligation on the vascular permeability in the gingiva and alv eolar mucosa encircling the mandibular left 1st molar was studied in r ats with and without capsaicin pretreatment. Vascular permeability was assessed by the Evans blue extravasation. Ligation caused a significa nt augmentation in vascular permeability of the gingivomucosal tissue at day 8 (right: 18.14+/-1.68 mu g g(-1); left (ligature): 38.21+/-2.4 3 mu g g(-1), n=8, p<0.001) and at day 14 (right: 20.31+/-1.71 mu g g( -1): left (ligature): 36.98+/-2.73 mu g g(-1), n=8, p<0.001). 4 days a fter ligation, no difference could be observed in vascular permeabilit y in the oral mucosa of the ligated side (left: 23.14+/-1.21 mu g g(-1 )) as compared to the side without ligature (right: 23.5+/-1.45 mu g g (-1), n=8, NS). There was no elevation of vascular permeability of gin givomuscosal tissue around the ligation in rats pretreated with capsai cin either in newborn age (right: 23.92+/-1.76 mu g g(-1); left (ligat ure): 23.51+/-2.16 mu g g(-1), n=8, NS) or in adult age (right: 20.61/-1.62 mu g g(-1); left (ligature): 20.85+/-1.07 mu g g(-1), n=8, NS). Light microscopical studies of oral mucosa revealed, that 8 and 14 da ys after the ligature placed around the mandibular left 1st molar of t he rat, there resulted an accumulation of inflammatory cells in the co nnective tissue. There was no inflammatory reaction in the gingivomuco sal tissue of the side of the ligature 4 days after ligature, neither could inflammatory reaction be detected 14 days following ligation in the oral mucosa of rats systemically pretreated with capsaicin either neonatally or in the adult. Based on these observations, it can be ass umed that neurogenic mechanism plays a crucial role in the development of inflammation in the oral cavity induced by mechanical and/or bacte rial stimulation frequently found in clinical practice.