title: Ingestion of dried-bonito broth (dashi) facilitates PV-parvalbumin-immunoreactive neurons in the brain, and affects emotional behaviors in mice.
abstract: OBJECTIVE
  Emerging evidence suggests that traditional diets and nutrition have a significant impact on brain development, and could contribute to the promotion of mental health and prevention of psychiatric disorders in children and adolescents. Moreover, deficits in parvalbumin (PV)-immunoreactive and/or GABAergic neurons are closely associated with various psychiatric disorders in children and adolescents. To investigate the possible neural mechanisms of diet involvement in mental health, we analyzed the effects of dried-bonito dashi (Japanese fish broth) (DBD) on PV-immunoreactive neurons and emotional behaviors in young mice.
  
  
  METHODS
  Male mice after weaning were fed DBD for 60 days, and tested with a resident-intruder test for aggressiveness and a forced swimming test for depression-like symptoms. After the behavioral testing, PV-immunoreactive neurons in the brain were immunohistochemically analyzed.
  
  
  RESULTS
  The results indicated that DBD intake decreased aggressiveness and depression-like symptoms, and increased the densities of PV-immunoreactive neurons in the medial prefrontal cortex (mPFC), amygdala, hippocampus, and superior colliculus. These behavioral changes were correlated with the densities of PV-immunoreactive neurons in the mPFC, amygdala, and hippocampus. However, subdiaphragmatic vagotomy did not affect the effects of DBD on emotional behaviors, although it nonspecifically decreased the densities of PV-immunoreactive neurons.
  
  
  CONCLUSIONS
  The results suggest that DBD might modulate emotional behaviors by promoting PV-immunoreactive and/or GABAergic neuronal activity through parallel routes. The present results highlight a new mechanism for diet involvement in brain functions, and suggest that DBD might have therapeutic potential for the promotion of mental health.
authors.affiliation: a System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences , University of Toyama , Sugitani, 2630, Toyama 930-0194 , Japan.
authors.forename: Undarmaa
authors.initials: U
authors.lastname: Jargalsaikhan
authors.affiliation: a System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences , University of Toyama , Sugitani, 2630, Toyama 930-0194 , Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishimaru
authors.affiliation: a System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences , University of Toyama , Sugitani, 2630, Toyama 930-0194 , Japan.
authors.forename: Jumpei
authors.initials: J
authors.lastname: Matsumoto
authors.affiliation: a System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences , University of Toyama , Sugitani, 2630, Toyama 930-0194 , Japan.
authors.forename: Yusaku
authors.identifier: http://orcid.org/0000-0001-6626-7259
authors.initials: Y
authors.lastname: Takamura
authors.affiliation: a System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences , University of Toyama , Sugitani, 2630, Toyama 930-0194 , Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Nakamura
authors.affiliation: a System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences , University of Toyama , Sugitani, 2630, Toyama 930-0194 , Japan.
authors.forename: Etsuro
authors.initials: E
authors.lastname: Hori
authors.affiliation: b Institute for Innovation, Ajinomoto Co., Inc. , Kawasaki 210-8681 , Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kondoh
authors.affiliation: a System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences , University of Toyama , Sugitani, 2630, Toyama 930-0194 , Japan.
authors.forename: Taketoshi
authors.initials: T
authors.lastname: Ono
authors.affiliation: a System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences , University of Toyama , Sugitani, 2630, Toyama 930-0194 , Japan.
authors.forename: Hisao
authors.initials: H
authors.lastname: Nishijo
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D003863:Depression / Q000175:diagnosis / Q000517:prevention & control; D004032:Diet; D004644:Emotions; D006624:Hippocampus / Q000166:cytology; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000502:physiology*; D010320:Parvalbumins / Q000502:physiology*; D010805:Physical Conditioning, Animal; D017397:Prefrontal Cortex / Q000166:cytology; D017747:Seafood; D013550:Swimming; D014628:Vagotomy
chemical_list: D010320:Parvalbumins
keywords: Amygdala; Emotion; Gut–brain axis; Hippocampus; Parvalbumin-immunoreactive neuron; Prefrontal cortex