Neuronally modulated transcription of a glycine transporter in rat dorsal cochlear nucleus and nucleus of the medial trapezoid body

Neurotransmitter transporters limit transmitter concentration at the postsy naptic membrane by removing neurotransmitters from the synaptic cleft. Not only do neurotransmitter transporters contribute to the regulation of synap tic transmission, but they themselves might be dynamically regulated by neu ronal activity of the neurons in which they are expressed. In this experime nt, we investigated the question of whether the transcription of two differ ent glycine transporters, Glyt1 and Glyt2, is influenced by neuronal activi ty. These transporters are found in the dorsal cochlear nucleus (DCN) and m edial nucleus of the trapezoid body. Glytl and Glyt2 mRNA were measured by using hybridization histochemistry and a semiquantitative reverse transcrip tion polymerase chain reaction. Decreases in auditory primary afferent acti vity, caused by either unilateral labyrinthectomy or disruption of the midd le ear ossicles, caused a reduction in Glyt2, but not Glytl mRNA in the ips ilateral DCN and in the contralateral medial nucleus of the trapezoid body. Acoustic stimulation at either 10 kHz or 40 kHz was used to provide contro lled increases in primary afferent activity, evoking localized increases in Glyt2 mRNA in clusters of neurons in the DCN. The location of these cluste rs corresponded to the regions of the auditory tonotopic map devoted to the se frequencies. The duration of changes in Glyt2 mRNA evoked by unilateral labyrinthectomy, measured with the reverse transcription polymerase chain r eaction, was 5-10 days. These data provide the first example of in vivo reg ulation of transporter transcription by neuronal activity. (C) 1999 Wiley-L iss, Inc.