Histamine elicits neuronal excitatory response of red nucleus in the rat via H2 receptors in vitro.
Perfusing slices with histamine (1-100 microM) produced an excitatory response in rat rubral neurons (118/132, 89.4%). The histamine-induced excitation was not blocked by the low-Ca2+/high-Mg2+ medium (n=10), supporting a direct postsynaptic action of the amine. Histamine H2 receptor antagonist ranitidine effectively blocked the excitatory response of rubral neurons to histamine (n=26), but H1 receptor antagonist triprolidine did not (n=24). The excitatory effect of histamine could be mimicked by dimaprit, a highly selective H2 receptor agonist (n=24), and the dimaprit-elicited excitation of the rubral neurons could be blocked by ranitidine (n=16), but not by triprolidine (n=9). In addition, H1 receptor agonist 2-pyridylethylamine could not elicit any response in rubral neurons (n=12). These results indicate that histamine excites red nucleus neurons through H2 receptors and suggest that the histaminergic afferent fibers may play an important functional role in the sensorimotor integration through the red nucleus.
Chen
Kun
K
Department of Biological Science and Technology, Nanjing University, 22 Hankou Road, Nanjing 210093, China.
Zhu
Jing-Ning
JN
Li
Hong-Zhao
HZ
Wang
Jian-Jun
JJ
D000818:Animals; D004594:Electrophysiology; D006632:Histamine / Q000494:pharmacology / Q000502:physiology*; D017442:Histamine Agonists / Q000494:pharmacology; D006633:Histamine Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011970:Receptors, Histamine H2 / Q000187:drug effects / Q000502:physiology; D012012:Red Nucleus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*
D017442:Histamine Agonists; D006633:Histamine Antagonists; D011970:Receptors, Histamine H2; D006632:Histamine