title: [The effect of central histamine H3 receptor on breathing activity of asthmatic guinea pigs].
abstract: OBJECTIVE
  To investigate the effect of selective H3 receptor agonist(R)-alpha-methylhistamine and antagonist thioperamide on the respiratory response in asthmatic guinea pigs respectively.
  
  
  METHODS
  Anesthesized guinea pigs were prepared with a implanted intracerebroventricular (icv) cannula and instrumented for the measurement of respiratory rate (RR) and diaphragmatic electric activity (DA). Substance P-like immunoreactive (SP-LI) substances in lower respiratory tract were detected by immunohistochemical method. Brain histamine contents were measured by fluorometric determination.
  
  
  RESULTS
  (1) Intravenous injection of ovalbumin caused tachypnea and significant decrease in DA magnitude. At the same time, SP-LI substances increased in trachea, bronchus and lung. (2) Administration of selective H3 receptor agonist (R)-alpha-methylhistamine (5 microg) icv immediately after i.v. ovalbumin could significantly ameliorate the changes in RR and DA induced by ovalbumin. In accordance, SP-LI substances in lower respiratory tract markedly decreased at 5 min and 10 min after (R)-alpha-methylhistamine microinjection. (3) Icv thioperamide (20 microg) caused a significant increase in RR and a decrease in DA. (4) Brain histamine contents increased in hypothalamus and cortex during asthma. After microinjection of thioperamide (20 microg) icv significant increase of histamine contents in hypothalamus and cortex was observed.
  
  
  CONCLUSIONS
  Brain histamine H3 receptors may be related to asthmatic respiratory responses.
authors.affiliation: Department of Physiology, Medical College of Southeast University, Nanging 210009, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Dong
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.forename: Bao-Shen
authors.initials: BS
authors.lastname: Lu
mesh_terms: D000818:Animals; D001249:Asthma / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D006168:Guinea Pigs; D017442:Histamine Agonists / Q000494:pharmacology; D054828:Histamine H3 Antagonists / Q000494:pharmacology; D020547:Lateral Ventricles; D008297:Male; D008761:Methylhistamines / Q000494:pharmacology; D009119:Muscle Contraction; D010880:Piperidines / Q000494:pharmacology; D018100:Receptors, Histamine H3 / Q000378:metabolism*; D013373:Substance P / Q000378:metabolism; D014132:Trachea / Q000503:physiopathology
chemical_list: D017442:Histamine Agonists; D054828:Histamine H3 Antagonists; D008761:Methylhistamines; D010880:Piperidines; D018100:Receptors, Histamine H3; D013373:Substance P; C069357:alpha-methylhistamine; C052075:thioperamide