title: Oral administration of 5-hydroxytryptophan aggravated periodontitis-induced alveolar bone loss in rats.
abstract: OBJECTIVE
  5-Hydroxytryptophan (5-HTP) is the precursor of serotonin and 5-HTP has been widely used as a dietary supplement to raise serotonin level. Serotonin has recently been discovered to be a novel and important player in bone metabolism. As peripheral serotonin negatively regulates bone, the regular take of 5-HTP may affect the alveolar bone metabolism and therefore influence the alveolar bone loss induced by periodontitis. The aim of this study was to investigate the effect of 5-HTP on alveolar bone destruction in periodontitis.
  
  
  METHODS
  Male Sprague-Dawley rats were randomly divided into the following four groups: (1) the control group (without ligature); (2) the 5-HTP group (5-HTP at 25 mg/kg/day without ligature); (3) the L group (ligature+saline placebo); and (4) the L+5-HTP group (ligature+5-HTP at 25 mg/kg/day). Serum serotonin levels were determined by ELISA. The alveolar bones were evaluated with micro-computed tomography and histology. Tartrate-resistant acid phosphatase staining was used to assess osteoclastogenesis. The receptor activator of NF-kB ligand (RANKL) and osteoprotegerin (OPG) expression in the periodontium as well as the interleukin-6 positive osteocytes were analysed immunohistochemically.
  
  
  RESULTS
  5-HTP significantly increased serum serotonin levels. In rats with experimental periodontitis, 5-HTP increased alveolar bone resorption and worsened the micro-structural destruction of the alveolar bone. 5-HTP also stimulated osteoclastogenesis and increased RANKL/OPG ratio and the number of IL-6 positive osteocytes. However, 5-HTP treatment alone did not cause alveolar bone loss in healthy rats.
  
  
  CONCLUSIONS
  The present study showed that 5-HTP aggravated alveolar bone loss, deteriorated alveolar bone micro-structure in the presence of periodontitis, which suggests 5-HTP administration may increase the severity of periodontitis.
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, PR China; West China College of Stomatology, Sichuan University, Chengdu 610041, PR China.
authors.forename: Xianxian
authors.initials: X
authors.lastname: Li
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, PR China; West China College of Stomatology, Sichuan University, Chengdu 610041, PR China.
authors.forename: Xiangnan
authors.initials: X
authors.lastname: Wu
authors.affiliation: Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou 510055, PR China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, PR China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, PR China; West China College of Stomatology, Sichuan University, Chengdu 610041, PR China.
authors.forename: Zhichao
authors.initials: Z
authors.lastname: Hao
authors.affiliation: Chongqing Key Laboratory for Oral Diseases and Biomedical Sciences, Chongqing 401147, PR China; The Affiliated Hospital of Stomatology, Chongqing Medical University, Chongqing 401147, PR China.
authors.forename: Shenyuan
authors.initials: S
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, PR China; West China College of Stomatology, Sichuan University, Chengdu 610041, PR China.
authors.forename: Taozi
authors.initials: T
authors.lastname: Fu
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, PR China; West China College of Stomatology, Sichuan University, Chengdu 610041, PR China.
authors.forename: Helin
authors.initials: H
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, PR China; West China College of Stomatology, Sichuan University, Chengdu 610041, PR China. Electronic address: wanghang@scu.edu.cn.
authors.forename: Hang
authors.initials: H
authors.lastname: Wang
mesh_terms: D006916:5-Hydroxytryptophan / Q000008:administration & dosage* / Q000494:pharmacology*; D000284:Administration, Oral; D016301:Alveolar Bone Loss / Q000139:chemically induced* / Q000000981:diagnostic imaging; D000818:Animals; D018450:Disease Progression; D004797:Enzyme-Linked Immunosorbent Assay; D007124:Immunoenzyme Techniques; D015850:Interleukin-6 / Q000378:metabolism; D008297:Male; D010010:Osteoclasts / Q000187:drug effects; D010011:Osteocytes / Q000187:drug effects; D010518:Periodontitis / Q000150:complications*; D053245:RANK Ligand / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D053246:Receptor Activator of Nuclear Factor-kappa B / Q000378:metabolism; D012701:Serotonin / Q000097:blood; D055114:X-Ray Microtomography
chemical_list: D015850:Interleukin-6; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D012701:Serotonin; D006916:5-Hydroxytryptophan
keywords: 5-Hydroxytryptophan; Alveolar bone loss; Osteoclast; Osteocyte; Periodontitis; Serotonin