Differences in developmental changes in GABAergic response between bushy and stellate cells in the rat anteroventral cochlear nucleus

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• 作者：Ning-ying Song ; Hai-bo Shi ; ^{haibo99@hotmail.com} ; Chun-yan Li ; Shan-kai Yin ; ^{yinshankai@china.com}
• 关键词：Auditory ; Hearing ; Gramicidin-perforated patch cl In vitro ; Reversal potential
• 刊名：International Journal of Developmental Neuroscience
• 出版年：2012
• 出版时间：August, 2012
• 年：2012
• 卷：30
• 期：5
• 页码：397-403
• 全文大小：727 K

文摘

Many mammalian central nervous system neuron responses mediated by GABA_A receptors undergo a developmental transition from excitation to inhibition, but little is known about the time of this switch in specific cell types in the developing anteroventral cochlear nucleus (AVCN). In the present study, bushy and stellate cells, two major cell types in the AVCN, were identified according to their morphology and electrophysiology. The equilibrium potential of GABA-evoked currents (E_GABA) was examined using the gramicidin-perforated patch-clamp technique. We found that the action of GABA in bushy and stellate cells switched from predominantly depolarizing to predominantly hyperpolarizing with respect to their resting membrane potential (V_rest) at different postnatal ages. Such a switch in the GABA response of bushy cells occurred before the first postnatal week, whereas that in stellate cells happened at the end of the second postnatal week. Furthermore, we discovered that bushy cells had a more depolarized V_rest than did stellate cells before the second postnatal week; however, the E_GABA of bushy and stellate cells was not significantly different. Thus, the discrepancy in the timing of the developmental shift from depolarizing to hyperpolarizing GABA responses between bushy and stellate cells may be due to the difference in their V_rest, but not due to E_GABA itself. These results suggest that GABAergic inhibition functions earlier in bushy than in stellate cells. In contrast, the longer excitatory action of GABA on stellate cells possibly renders them more vulnerable than bushy cells to excitotoxic substances during early development.