title: The Association between Baseline Subjective Anxiety Rating and Changes in Cardiac Autonomic Nervous Activity in Response to Tryptophan Depletion in Healthy Volunteers.
abstract: The aim of this study was to investigate the influence of serotonin on anxiety and autonomic nervous system (ANS) function; the correlation between subjective anxiety rating and changes of ANS function following tryptophan depletion (TD) in healthy volunteers was examined. Twenty-eight healthy participants, consisting of 15 females and 13 males, with an average age of 33.3 years, were recruited.Baseline Chinese Symptom Checklist-90-Revised and ANS function measurements were taken. TD was carried out on the testing day, and participants provided blood samples right before and 5 hours after TD. ANS function, somatic symptoms, and Visual Analogue Scales (VASs) were determined after TD. Wilcoxon signed rank test and Spearman ρ correlation were adapted for analyses of the results.The TD procedure reduced total and free plasma tryptophan effectively. After TD, the sympathetic nervous activity increased and parasympathetic nervous activity decreased. Baseline anxiety ratings positively correlated with post-TD changes in sympathetic nervous activity, VAS ratings, and physical symptoms. However, a negative correlation with post-TD changes in parasympathetic nervous activity was found.The change in ANS function after TD was associated with the severity of anxiety in healthy volunteers. This supports the fact that the effect of anxiety on heart rate variability is related to serotonin vulnerability. Furthermore, it also shows that the subjective anxiety rating has a biological basis related to serotonin.
authors.affiliation: From the Department of Psychiatry, National Cheng Kung University Hospital (CYH, HCT, MHC, KCC, PSC, IHL, TLY, YKY), College of Medicine; Addiction Research Center (CYH, KCC, PSC, IHL, TLY, YKY), National Cheng Kung University, Tainan; Department of Psychiatry (HCT, KCC, YKY), National Cheng Kung University Hospital, Dou-Liou Branch, Yunlin; and Institute of Behavioral Medicine (YKY), College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Chih Yin
authors.initials: CY
authors.lastname: Hsiao
authors.forename: Hsin Chun
authors.initials: HC
authors.lastname: Tsai
authors.forename: Mei Hung
authors.initials: MH
authors.lastname: Chi
authors.forename: Kao Chin
authors.initials: KC
authors.lastname: Chen
authors.forename: Po See
authors.initials: PS
authors.lastname: Chen
authors.forename: I Hui
authors.initials: IH
authors.lastname: Lee
authors.forename: Tzung Lieh
authors.initials: TL
authors.lastname: Yeh
authors.forename: Yen Kuang
authors.initials: YK
authors.lastname: Yang
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000008:administration & dosage; D001007:Anxiety / Q000097:blood*; D001341:Autonomic Nervous System / Q000378:metabolism* / Q000502:physiology; D005260:Female; D064368:Healthy Volunteers; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D012701:Serotonin / Q000097:blood*; D018709:Statistics, Nonparametric; D014364:Tryptophan / Q000097:blood*; D064232:Visual Analog Scale
chemical_list: D000596:Amino Acids; D012701:Serotonin; D014364:Tryptophan