Effects of hydrogen sulfide on periodontal tissue remodeling of orthodontic tooth in rats

Abstract

Objective To assess the effects of H2S on periodontal tissue remodeling and possible interaction between H2S and NO in rat model of orthodontic tooth movement (OTM).Methods The OTM models were established in three groups of 45 male Sprague-Dawley rats.The rats in the negativecontrol group (Group A) received injection of sterile phosphate-buffered saline (PBS),and those in the treatment group (Group B) and positive control group (Group C) respectively received 40 mg/ml DL-propargylglycine (PPG) and NG-Nitro-L-arginine Methyl Ester (L-NAME).Histochemistry and immunohistochemistry were performed respectively to exam the number of tartrate-resistant acid phosphatase(TRAP) positive osteoclast and expression of cystathionine γ-lyase (CSE) and inducible nitric oxide sythase (iNOS) in the tissue sections containing intact roots and periodontal tissues of the first molar on day 7,14 and 21 after appliance insertion.Results Group B had lest osteoclasts on day 7,compared to the other two groups(P＜0.01) while Group C showed the most expression of CSE.Increasing number of osteoclasts were observed in the first 14 days but followed with a decrease on day 21 in Group B.Osteoclast number decreased in Group A and C during the course.The expressions of both enzymes were down-regulated gradually.On day 21,CSE expression was negative whereas iNOS remained relative high expression(P＜0.01).Conclusions Application of 40 mg/ml PPG can reduce the generation of the endogenous H2S,and prevent osteoclasts from recruiting in the early stage of OTM.There may be down-regulation effect between NO/iNOS and H2 S/CSE during orthodontic periodontal tissue remodeling. Key words: gasotransmitter; hydrogen sulfide; nitricoxide; orthodontic tooth movement; periodontal tissue remodeling