title: The changes in plasma serotonin levels after hormone therapy and their relationship with estrogen responsiveness on bone in postmenopausal women.
abstract: BACKGROUND
  Selective serotonin reuptake inhibitors have shown to be associated with an increased risk of fractures. It has been suggested that circulating serotonin is an important regulatory factor and that estrogen may regulate bone metabolism through the serotonin pathway.
  
  
  OBJECTIVE
  Our objective was to determine the association between plasma serotonin level and bone turnover before and after hormone therapy (HT) in postmenopausal women.
  
  
  METHODS
  In this parallel comparative study using age-matched controls, 80 postmenopausal women (21 control, 59 receiving HT) aged 46-64 yr were assessed. The plasma levels of serotonin, serum concentrations of osteocalcin and carboxyterminal telopeptides, and bone mineral density (BMD) were measured at baseline and after 3 months and 1 yr of HT.
  
  
  RESULTS
  The plasma serotonin level was significantly correlated with serum total alkaline phosphatase level at baseline (r = -0.223, P = 0.048) but not with serum osteocalcin (r = -0.217, P = 0.056) or carboxyterminal telopeptides (r = -0.217, P = 0.054). There was no significant association between baseline serotonin and BMD measured at the spine or femur. The median decrements of circulating serotonin from baseline were -9.3% (interquartile range -34.0 to 53.6%) and -7.2% (-25.5 to 64.5%) at 3 months and 1 yr of HT, respectively. These changes were not significantly different from those in the control group. The short-term changes of circulating serotonin at 3 months after HT did not show significant association with the changes in BMD measured at the lumbar spine or proximal femur 1 year after HT.
  
  
  CONCLUSIONS
  Our results suggest that circulating serotonin may reflect bone turnover status, but it is not a strong enough predictor of bone loss to use as a bone marker. Moreover, serial measurements of plasma serotonin after short-term treatment with estrogen cannot predict the long-term responsiveness of bone to estrogen, suggesting that the bone-preserving effect of estrogen is independent of the peripheral action of serotonin on bone.
authors.affiliation: Department of Endocrinology and Metabolism, Cheil General Hospital and Women's Healthcare Center, Kwandong University College of Medicine, 1-19 Mukjung Dong, Choong Gu, Seoul 100-380, Korea.
authors.forename: Ha Young
authors.initials: HY
authors.lastname: Kim
authors.forename: Mi Hyun
authors.initials: MH
authors.lastname: Park
authors.forename: Hyun Koo
authors.initials: HK
authors.lastname: Yoon
authors.forename: Ki Ok
authors.initials: KO
authors.lastname: Han
mesh_terms: D015415:Biomarkers / Q000097:blood; D015519:Bone Density / Q000187:drug effects / Q000502:physiology*; D016723:Bone Remodeling / Q000187:drug effects / Q000502:physiology; D024042:Collagen Type I / Q000097:blood; D015914:Estrogen Replacement Therapy / Q000379:methods*; D004967:Estrogens / Q000097:blood* / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood; D010455:Peptides / Q000097:blood; D017698:Postmenopause / Q000097:blood*; D011237:Predictive Value of Tests; D012701:Serotonin / Q000097:blood*
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D004967:Estrogens; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D015675:Osteocalcin; D012701:Serotonin