Muscarinic regulation of spontaneously active medial vestibular neurons in vitro.
We examined the effects of cholinergic agonists and antagonists on spontaneously occurring action potentials extracellularly recorded from medial vestibular nucleus (MVN) neurons in rat brainstem slice preparation to elucidate the cholinergic mechanism involved in excitation. Addition of carbachol (10(-6)-10(-5) M) and muscarine (10(-6)-10(-5) M) into the bath dose-dependently increased the spontaneous firing rate, while nicotine (10(-5)-10(-4) M) had no effects. Acetylcholine (10(-6)-10(-5) M) in the presence of physostigmine (10(-7) M) also increased the firing rate in a dose-dependent manner. Conversely, atropine (10(-8)-3 x 10(-7) M) slightly decreased the firing and dose-dependently inhibited the carbachol-induced increase in the firing rate. These results suggest that the firing rate of spontaneously active MVN neurons are regulated by acetylcholine via muscarinic receptors.
Ujihara
H
H
Department of Pharmacology, Faculty of Medicine, Kyoto University, Japan.
Akaike
A
A
Sasa
M
M
Takaori
S
S
D000109:Acetylcholine / Q000494:pharmacology*; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002799:Cholinergic Fibers / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology*; D014726:Vestibular Nuclei / Q000187:drug effects / Q000502:physiology*
D011976:Receptors, Muscarinic; D000109:Acetylcholine