[Modulation of gamma-aminobutyric acid receptor on medial vestibular nucleus neurons in vivo].
OBJECTIVE
To investigate modulation of gamma-aminobutyric acid (GABA) and its receptors on medial vestibular nucleus neurons in vivo.


METHODS
Twenty-six male Wistar rats were used. gamma-aminobutyric acid, bicuculline (BIC, gamma-aminobutyric acid A receptor antagonist) and 2-hydroxysaclofen (SAC, gamma-aminobutyric acid B receptor antagonist) were microiontophoresed on medial vestibular nucleus (MVN) neurons to determine the effects of gamma-aminobutyric acid and its antagonists on the neuronal firing rates of medial vestibular nucleus in rats in vivo.


RESULTS
Microiontophoretic application of y-aminobutyric acid at 10, 30, 50 nA electric current produced inhibitory responses on 42 MVN neurons, these responses were dose-dependent decreases, firing rates (x +/- s) of MVN neurons decreased form (14.8 +/- 5.6) times/s to (8.7 +/- 3.4) times/s, (4.1 +/- 1.6) times/s and (2.2 +/- 1.1) times/s respectively; microiontophoretic application of bicuculline in 37 MVN neurons, 86.5% (32/37) neurons produced excitatory responses, 13.5% (5/37) neurons didn't response, firing rates of MVN neurons increased form (15.3 +/- 6.3) times/s to (16.8 +/- 7.1) times/s, (25.9 +/- 10.1) times/s and (32.7 +/- 11.3) times/s respectively at 10, 30, 50 nA electric current, which were dose-dependent increases, and the inhibitory responses of gamma-aminobutyric acid on MVN neurons were blocked by bicuculline completely; however, microiontophoretic application of 2-hydroxysaclofen didn't produced responses as bicuculline did.


CONCLUSIONS
Modulation of gamma-aminobutyric acid on medial vestibular nucleus neurons was mediated by y-aminobutyric acid A receptor in vivo.
Wang
Xu-wu
XW
Department of Otorhinolaryngology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
Kong
Wei-jia
WJ
D000818:Animals; D004594:Electrophysiology; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D018079:Receptors, GABA / Q000378:metabolism*; D014726:Vestibular Nuclei / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D018079:Receptors, GABA; D005680:gamma-Aminobutyric Acid