Electrophysiological evidence for cholinoceptive neurons in the medial vestibular nucleus: studies on rat brain stem in vitro.
Electrophysiological studies were performed to determine whether or not cholinoceptive neurons are present in the rat medial vestibular nucleus (MVN) using brainstem slice preparations. Fifty-three MVN neurons, whose activities were extracellularly recorded, fired spikes spontaneously and regularly with an interspike interval of 180 +/- 27 ms (mean +/- S.E.M.) and a coefficient of variation of 0.11 +/- 0.02. Intracellularly recorded neurons also exhibited similar spontaneous and regular generation of action potentials. Carbachol dose-dependently increased the spontaneous firing, although the firing rate was decreased in a few neurons. The addition of atropine reduced the firing rate, and dose-dependently attenuated the carbachol-induced excitation of the neurons. In a low Ca2+ and high Mg2+ medium, carbachol also increased the firing rate. These results indicate that the MVN contains neurons with spontaneous and regular firing, and that the excitability of these neurons is regulated by a cholinergic muscarinic mechanism.
Ujihara
H
H
Department of Pharmacology, Faculty of Medicine, Kyoto University, Japan.
Akaike
A
A
Sasa
M
M
Takaori
S
S
D000818:Animals; D001285:Atropine; D002217:Carbachol; D004594:Electrophysiology; D008297:Male; D009474:Neurons / Q000032:analysis*; D051381:Rats; D011919:Rats, Inbred Strains; D011950:Receptors, Cholinergic / Q000032:analysis* / Q000502:physiology; D014726:Vestibular Nuclei / Q000032:analysis*
D011950:Receptors, Cholinergic; D001285:Atropine; D002217:Carbachol