Histamine Excites Rat Superior Vestibular Nuclear Neurons via Postsynaptic H

The superior vestibular nucleus (SVN), which holds a key position in vestibulo-ocular reflexes and nystagmus, receives direct hypothalamic histaminergic innervations. By using rat brainstem slice preparations and extracellular unitary recordings, we investigated the effect of histamine on SVN neurons and the underlying receptor mechanisms. Bath application of histamine evoked an excitatory response of the SVN neurons, which was not blocked by the low-Ca 2+ /highMg 2+ medium, indicating a direct postsynaptic effect of the amine. Selective histamine H 1 receptor agonist 2-pyridylethylamine and H 2 receptor agonist dimaprit, rather than VUF8430, a selective H 4 receptor agonist, mimicked the excitation of histamine on SVN neurons. In addition, selective H 1 receptor antagonist mepyramine and H 2 receptor antagonist ranitidine, but not JNJ7777120, a selective H 4 receptor antagonist, partially blocked the excitatory response of SVN neurons to histamine. Moreover, mepyramine together with ranitidine nearly totally blocked the histamine-induced excitation. Immunostainings further showed that histamine H 1 Received: March 20, 2012 Accepted after revision: May 31, 2012 Published online: September 20, 2012 Jian-Jun Wang and Jing-Ning Zhu School of Life Sciences, Mailbox 426 Nanjing University, 22 Hankou Road Nanjing 210093 (PR China) Tel. +86 25 8359 2714, E-Mail jjwang @ nju.edu.cn and jnzhu @ nju.edu.cn © 2012 S. Karger AG, Basel 1424–862X/13/0214–0174$38.00/0 www.karger.com/nsg Th is is an Open Access article licensed under the terms of the Creative Commons Attribution-NonCommercial 3.0 Unported license (CC BY-NC) (www.karger.com/OA-license), applicable to the online version of the article only. Distribution permitted for non-commercial purposes only. D ow nl oa de d by : 54 .7 0. 40 .1 1 11 /1 9/ 20 17 7 :1 0: 10 P M