Cellular NeuroscienceResearch PaperRegulation of glutamatergic and GABAergic neurotransmission in the chick nucleus laminaris: role of N-type calcium channels
Section snippets
Slice preparation and in vitro whole-cell recordings
Fertilized chicken eggs (Gallus domesticus) were purchased from Purdue University (West Lafayette, IN) and incubated using an RX2 Auto Turner (Lyon Electric Co., Chula Vista, CA, USA). Brainstem slices (250–300 μm in thickness) were prepared from late embryos (E18–E21) and early hatchlings (P6–P9) as previously described (Reyes et al., 1994, Tang et al., 2009), with modification of the artificial cerebrospinal fluid (ACSF) components used for dissection and cutting of the brain tissue. The
Effects of Ca2+ channel blockers on the excitatory transmission in the NL
The dorsal and ventral glutamatergic pathways to the NL were activated by the delivery of two separate electrical stimulations using two stimulus setups (Fig. 1C), with an inter-stimulus interval of 75 ms. This interval is long enough to avoid any interactions between the two EPSCs, as responses elicited by the individual stimuli alone were the same as those elicited when both stimuli were presented at the interval of 75 ms (data not shown). Stimulus intensities were adjusted to give rise to
Discussion
The main finding of this study is that N-type VGCCs play a dominant role in triggering both the excitatory and the inhibitory transmission in NL neurons. Furthermore, I found that the same types of VGCCs mediate the ipsilateral and the contralateral glutamatergic transmission in individual NL neurons, and that the ipsilateral and the contralateral EPSCs have the same kinetics. Herein, I provide the first evidence at the cellular level of physiological symmetry between the two segregated
Acknowledgments
This work was supported by Northeastern Ohio Universities Colleges of Medicine and Pharmacy startup funds, and the National Institute on Deafness and other Communication Disorders Grant R01 DC008984 to YL. The author thanks Dr. Hongxiang Gao for technical assistance, Ms. Susan Motts and Dr. Kyle Nakamoto for taking the photographs presented in Fig. 1, and Dr. Zheng-Quan Tang and the anonymous reviewer for critical comments on an earlier version of the manuscript.
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