title: The neurosteroid pregnenolone sulfate excites medial vestibular nucleus neurons.
abstract: To examine the relationship between neurosteroids and vertigo we performed electrophysiological studies to determine whether pregnenolone sulfate (PS) affects the activity of medial vestibular nucleus (MVN) neurons in alpha-chloralose-anesthetized cats. Single neuronal activities in the MVN were recorded extracellularly using a glass-insulated silver wire microelectrode attached along a seven-barreled micropipette. 3 mM PS, 1 M glutamate and 3 mM NaCl were applied microiontophoretically in the immediate vicinity of the target neurons. The effects of these drugs were then examined on type I and type II neurons, identified by their responses to horizontal and sinusoidal rotations. The iontophoretic application of PS dose-dependently increased the spontaneous firing of both type I and type II neurons. The larger increase in firing was observed in type I neurons as compared with type II neurons following the PS application. These results suggest that PS excites types I and II neurons differentially, presumably resulting in a disturbance of harmony of the vestibulo-ocular reflex with ensuing development of vertigo.
authors.affiliation: Department of Otorhinolaryngology, Nara Medical University, Kashihara-city, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: T
authors.initials: T
authors.lastname: Yamanaka
authors.forename: H
authors.initials: H
authors.lastname: Miyahara
authors.forename: T
authors.initials: T
authors.lastname: Matsunaga
mesh_terms: D000818:Animals; D002415:Cats; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D018698:Glutamic Acid / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D011284:Pregnenolone / Q000494:pharmacology*; D012965:Sodium Chloride / Q000494:pharmacology; D014726:Vestibular Nuclei / Q000166:cytology / Q000187:drug effects* / Q000502:physiology
chemical_list: C018370:pregnenolone sulfate; D018698:Glutamic Acid; D012965:Sodium Chloride; D011284:Pregnenolone