Effects of L-baclofen and D-baclofen on the auditory system: a study of click-evoked potentials from the inferior colliculus in the rat.
The drug baclofen is a potential treatment for severe tinnitus, but its action in relieving tinnitus is not known. Baclofen is available as an approved drug only in racemic form with about equal content of the two enantiomers. In the present paper we show that L-baclofen causes a considerable (40.7%) suppression of the amplitude of the second peak in the click-evoked response from the cochlear nucleus. Bipolar recordings from the external nucleus of the inferior colliculus showed that L-baclofen caused a reduction in the amplitude of three or four distinct peaks in this response. D-Baclofen had no detectable effect on the response from the cochlear nucleus, and had only a slight effect on one component of the response from the external nucleus of the inferior colliculus. The demonstrated effect of L-baclofen on excitation in the ascending auditory pathway indicates that this drug may be a potential treatment for hyperactive auditory disorders such as tinnitus and hyperacusis.
Szczepaniak
W S
WS
Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pennsylvania, USA.
Møller
A R
AR
D000818:Animals; D001418:Baclofen / Q000494:pharmacology*; D017626:Cochlear Nucleus / Q000187:drug effects*; D005072:Evoked Potentials, Auditory; D007245:Inferior Colliculi / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
D001418:Baclofen