title: Activation of histamine H1 receptors in the nucleus tractus solitarii attenuates cardiac baroreceptor reflex function in rats.
abstract: OBJECTIVE
  The nucleus tractus solitarii (NTS) is a central brainstem structure that plays an important role in regulating cardiovascular homeostasis. In this study, we examined whether H1 receptors in the NTS can control the baroreceptor reflex function by modulating synaptic transmission.
  
  
  METHODS
  Cardiac baroreceptor reflex function was assessed before and after the microinjection of 2-pyridylethylamine (10-25 nmol), a histamine H1 receptor-specific agonist, into the NTS of urethane-anaesthetized Wistar rats. The cardiovascular responses induced by l-glutamate microinjection into the NTS were also examined before and after the NTS administration of 2-pyridylethylamine.
  
  
  RESULTS
  Nucleus tractus solitarii microinjections of 2-pyridylethylamine significantly inhibited the gain of the cardiac baroreceptor reflex and bradycardiac/depressor responses induced by l-glutamate microinjection into the NTS. These findings suggest that histamine H1 receptors regulate the cardiac baroreceptor reflex in a post-synaptic manner to inhibit barosensitive NTS neurons.
  
  
  CONCLUSIONS
  Taken together with our previous findings, the present results provide further evidence that histamine may play a role within the NTS in regulating cardiovascular homeostasis.
authors.affiliation: Department of Physiology, Wakayama Medical University School of Medicine, Wakayama, Japan; Department of Therapeutic Health Promotion, Kansai University of Health Sciences, Osaka, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Takagishi
authors.forename: S S
authors.initials: SS
authors.lastname: Gouraud
authors.forename: M E R
authors.initials: ME
authors.lastname: Bhuiyan
authors.forename: A
authors.initials: A
authors.lastname: Kohsaka
authors.forename: M
authors.initials: M
authors.lastname: Maeda
authors.forename: H
authors.initials: H
authors.lastname: Waki
mesh_terms: D000818:Animals; D017704:Baroreflex / Q000187:drug effects* / Q000502:physiology; D018698:Glutamic Acid / Q000494:pharmacology; D017442:Histamine Agonists / Q000494:pharmacology*; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D011725:Pyridines / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D011969:Receptors, Histamine H1 / Q000502:physiology*; D017552:Solitary Nucleus / Q000187:drug effects* / Q000502:physiology
chemical_list: D017442:Histamine Agonists; D011725:Pyridines; D011969:Receptors, Histamine H1; D018698:Glutamic Acid; C006183:2-(2-aminoethyl)pyridine
keywords: baroreceptor reflex; histamine; nucleus tractus solitarii