title: Anti-stress effects of drinking green tea with lowered caffeine and enriched theanine, epigallocatechin and arginine on psychosocial stress induced adrenal hypertrophy in mice.
abstract: BACKGROUND
  Theanine, an amino acid in tea, has significant anti-stress effects on animals and humans. However, the anti-stress effects of drinking green tea have not yet been elucidated.
  
  
  OBJECTIVE
  The present study aimed to explore anti-stress effects of green tea and roles of tea components in a mouse model of psychosocial stress.
  
  
  METHODS
  We examined anti-stress effects of three types of green teas, theanine-rich "Gyokuro", standard "Sencha", and Sencha with lowered caffeine (low-caffeine green tea). Furthermore, the roles of tea components such as caffeine, catechins, and other amino acids in anti-stress effects were examined.
  
  
  METHODS
  To prepare low-caffeine green tea, plucked new tea leaves were treated with a hot-water spray. Mice were psychosocially stressed from a conflict among male mice under confrontational housing. Mice consumed each tea that was eluted with room temperature water ad libitum. As a marker for the stress response, adrenal hypertrophy was compared with mice that ingested water.
  
  
  RESULTS
  Caffeine was significantly lowered by spraying hot-water on tea leaves. While epigallocatechin gallate (EGCG) is the main catechin in tea leaves, epigallocatechin (EGC) was mainly infused into water at room temperature. Adrenal hypertrophy was significantly suppressed in mice that ingested theanine-rich and low-caffeine green tea that were eluted with water at room temperature. Caffeine and EGCG suppressed the anti-stress effects of theanine while EGC and arginine (Arg) retained these effects.
  
  
  CONCLUSIONS
  These results suggest that drinking green tea exhibits anti-stress effects, where theanine, EGC and Arg cooperatively abolish the counter-effect of caffeine and EGCG on psychosocial stress induced adrenal hypertrophy in mice.
authors.affiliation: Department of Neurophysiology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan; Tea Science Center, Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan. Electronic address: unno@u-shizuoka-ken.ac.jp.
authors.forename: Keiko
authors.initials: K
authors.lastname: Unno
authors.affiliation: Department of Neurophysiology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
authors.forename: Ayane
authors.initials: A
authors.lastname: Hara
authors.affiliation: Department of Neurophysiology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
authors.forename: Aimi
authors.initials: A
authors.lastname: Nakagawa
authors.affiliation: Department of Neurophysiology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Iguchi
authors.affiliation: Department of Functional Plant Physiology, Faculty of Agriculture, Shizuoka University, Shizuoka, Japan.
authors.forename: Megumi
authors.initials: M
authors.lastname: Ohshio
authors.affiliation: Department of Functional Plant Physiology, Faculty of Agriculture, Shizuoka University, Shizuoka, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Morita
authors.affiliation: Tea Science Center, Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan.
authors.forename: Yoriyuki
authors.initials: Y
authors.lastname: Nakamura
mesh_terms: D000311:Adrenal Glands / Q000187:drug effects / Q000473:pathology; D000818:Animals; D001120:Arginine / Q000494:pharmacology*; D002110:Caffeine / Q000009:adverse effects* / Q000494:pharmacology; D028241:Camellia sinensis / Q000737:chemistry*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D004347:Drug Interactions; D005971:Glutamates / Q000494:pharmacology / Q000627:therapeutic use*; D006984:Hypertrophy; D008297:Male; D051379:Mice; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use; D013315:Stress, Psychological / Q000188:drug therapy* / Q000473:pathology; D013662:Tea / Q000737:chemistry*; D013696:Temperature; D014867:Water
chemical_list: D005971:Glutamates; D010936:Plant Extracts; D013662:Tea; D014867:Water; D002110:Caffeine; C026166:theanine; D002392:Catechin; D001120:Arginine; C045651:epigallocatechin gallate; C057580:gallocatechol
keywords: Anti-stress effect; Arginine; Caffeine; Epigallocatechin; Green tea; Theanine