AIMTo explore the influence of GABAergic neurotransmitters and GABAA receptors on the auditory afferent impulses recorded in the brainstem evoked by electro-stimulation.

METHODSBrainstem slices were prepared using ddy/ddy mice of postnatal 0-5th days. The brainstem slices were stained with a voltage-sensitive dye(NK3041). The cut end of the vestibulocochlear nerve (nVIIIth) connected with slices was stimulated by a tungsten electrode, a 16 x 16 pixels silicon photodiode array apparatus was used to record the optical mapping from auditory brainstem slices. The data were analyzed by ARGUS-50/PDA software.

RESULTSThe spatial-temporal patterns of the excitatory propagation from the vestibulocochlear nerve (nVIIIth) to cochlear nucleus and vestibular nucleus were displayed with multiple-sites optical recording. The optical signal coming from one pixel consisted of a fast spike-like response and a following slow response. Inhibitory neurotransmitter GABA decreased the fast spike-like response and following slow response of evoked optical signals, while an antagonist BMI against GABAA receptors increased the both responses.

CONCLUSIONA 16 x 16 pixel silicon photodiode array apparatus can be used to record multiple-sites optical mapping evoked by electro-stimulation to the cut end of the vestibulocochlear nerve. The every optical signal consists of both presynaptic and postsynaptic elements. Inhibitory neurotransmitter GABA and an antagonist BMI of GABAA receptors can modulate the excitatory propagation of evoked optical signals.