title: Effect of oral administration of GABA on temperature regulation in humans during rest and exercise at high ambient temperature.
abstract: BACKGROUND
  Centric administration of gamma-aminobutyric acid (GABA) has been implicated to affect temperature regulation in animals during rest or under anesthesia. However, there are few reports concerning the effects of the oral administration of GABA on temperature regulation in humans during rest and exercise. In order to clarify the effects and underlying mechanisms, we measured several parameters related to temperature regulation of humans during rest and exercise at high ambient temperature (35 degrees C).
  
  
  METHODS
  On two occasions, eight endurance-trained men rested for 20 min and cycled at 65% VO2peak for 30 min. In control trial (trial-C), subjects drank the sample which was a sports drink of 200 mL (placebo) before the rest period. In another trial (trial-G), subjects drank the sample which was a sports drink containing 1000 mg of GABA (GABA drink) before the rest period.
  
  
  RESULTS
  In trial-G, the plasma GABA concentrations were maintained higher than those in trial-C during the experiment. An increase of esophageal temperature during rest and exercise was inhibited in trial-G. Sweat rate, and plasma catecholamine concentrations during exercise were inhibited in trial-G.
  
  
  CONCLUSIONS
  Esophageal temperature inhibition is suggested to be induced by the suppression of cold-sensitive neurons during rest, and the inhibition of plasma catecholamine concentrations caused by the GABA-induced attenuation of the sympathetic nervous system during exercise.
authors.affiliation: Department of Environmental Physiology for Exercise, Osaka City University, Graduate School of Medicine, 1-4-3 Asahimachi, Abeno-ku, Osaka 545-8585, Japan. m2025873@med.osaka-cu.ac.jp
authors.forename: Taiki
authors.initials: T
authors.lastname: Miyazawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Kawabata
authors.forename: Takashi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Daiki
authors.initials: D
authors.lastname: Imai
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hamamoto
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yoshikawa
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Miyagawa
mesh_terms: D000284:Administration, Oral; D000328:Adult; D001831:Body Temperature / Q000187:drug effects / Q000502:physiology; D001833:Body Temperature Regulation / Q000187:drug effects* / Q000502:physiology; D004837:Epinephrine / Q000097:blood; D015444:Exercise / Q000502:physiology*; D018682:GABA Agents / Q000008:administration & dosage / Q000494:pharmacology*; D006358:Hot Temperature; D006801:Humans; D008297:Male; D009638:Norepinephrine / Q000097:blood; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D012146:Rest / Q000502:physiology*; D013696:Temperature; D005680:gamma-Aminobutyric Acid / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D018682:GABA Agents; D005680:gamma-Aminobutyric Acid; D009638:Norepinephrine; D004837:Epinephrine