Effects of anti-vertigo drugs on medial vestibular nucleus neurons activated by horizontal rotation.
The effects of anti-vertigo drugs on medial vestibular nucleus (MVN) neurons were examined to assess the site and mode of action using cats anesthetized with alpha-chloralose. Single neuron activity in the MVN was extracellularly recorded using a silver wire microelectrode attached along a seven-barreled micropipette, each of which was filled with diphenhydramine, diphenidol, betahistine, glutamate or NaCl. Type I of the MVN neurons were identified according to the responses obtained when the animal placed on a turn-table was rotated sinusoidally. The effects of the drugs were examined on type I neurons which received impulses primarily from the labyrinth and sent them to the oculomotor nuclei. The microiontophoretic application of diphenhydramine, diphenidol and betahistine inhibited rotation-induced firing of type I MVN neurons. Diphenhydramine and diphenidol were more potent than betahistine. These results suggest that these drugs directly act on MVN neurons to reduce the responsiveness to rotatory stimulation.
Kawabata
A
A
Department of Pharmacology, Faculty of Medicine, Kyoto University, Japan.
Sasa
M
M
Kishimoto
T
T
Takaori
S
S
D000818:Animals; D001621:Betahistine / Q000494:pharmacology; D002415:Cats; D004155:Diphenhydramine / Q000494:pharmacology; D005971:Glutamates / Q000494:pharmacology; D018698:Glutamic Acid; D007478:Iontophoresis; D008297:Male; D009474:Neurons / Q000187:drug effects*; D010880:Piperidines / Q000494:pharmacology; D012399:Rotation; D012965:Sodium Chloride / Q000494:pharmacology; D014717:Vertigo / Q000188:drug therapy*; D014726:Vestibular Nuclei / Q000166:cytology / Q000187:drug effects*
D005971:Glutamates; D010880:Piperidines; D018698:Glutamic Acid; D012965:Sodium Chloride; D004155:Diphenhydramine; C004858:diphenidol; D001621:Betahistine