Effects of S-nitroso-N-acetylpenicillamine on the Neuronal Excitability of the Medial Vestibular Nuclear Neuron

J Korean Neurol Assoc > Volume 25(2); 2007 > Article

Journal of the Korean Neurological Association 2007;25(2): 199-205.

S-nitroso-N-acetylpenicillamine이 내측 전정핵 신경세포 흥분도에 미치는 영향

김후원, 조기현a 장수정b 정한성b 박종성b

조선대학교 의과대학 신경과학교실, 전남대학교 의과대학 신경과학교실a, 생리학교실b

Effects of S-nitroso-N-acetylpenicillamine on the Neuronal Excitability of the Medial Vestibular Nuclear Neuron

Hoo Won Kim

Department of Neurology, Chosun University College of Medicine, Departments of Neurologya and Physiologyb, Chonnam National University Medical School

Abstract

Background: The medial vestibular nucleus is the largest one among the vestibular nuclei and known to play important roles not only in normal vestibular information processing but also in vestibular compensation. Glutamate is known to have a key role in vestibular compensation via long term potentiation and depression. But the action of nitric oxide related with glutamate is poorly studied. This experiment was designed to explore the effects of nitric oxide on the neuronal activity of a rat medial vestibular nuclear neuron using a nitric oxide enhancing drug, S-nitroso-N-acetylpenicillamine (SNAP).
Methods: Experiments were carried out on Sprague-Dawley rats aged 14 to 17 days. Neurons of MVN were obtained via enzymatic dissociation of a microtomized rat brainstem. Whole-cell membrane potentials were recorded at room temperature by using standard patch-clamp techniques. Action potentials were obtained after administration of SNAP. Changes of potassium currents were recorded using SNAP and ODQ (1H-[1, 2, 4] oxadiazolo [4, 3-a] quinozalin-1-one), an inhibitor of guanylyl cyclase.
Results: The mean spike frequency of action potentials was increased by adding SNAP. The mean amplitude of afterhyperpolarization was decreased by adding SNAP. The mean potassium current of medial vestibular nuclear neurons was decreased by SNAP. ODQ inhibited the SNAP-induced potassium currents.
Conclusions: These results suggest that nitric oxide increases the neuronal activity of rat medial vestibular nuclear neurons by inhibiting potassium currents via a cGMP dependent mechanism.KeyWords:S-nitroso-N-acetylpenicillamine, Nitric oxide, Medial vestibular nucleus, Action potential