TY - JOUR
T1 - KCNQ Channels Enable Reliable Presynaptic Spiking and Synaptic Transmission at High Frequency
AU - Zhang, Yihui
AU - Li, Dainan
AU - Darwish, Youad
AU - Fu, Xin
AU - Trussell, Laurence O.
AU - Huang, Hai
N1 - Publisher Copyright:
Copyright © 2022 the authors
PY - 2022/4/20
Y1 - 2022/4/20
N2 - The presynaptic action potential (AP) is required to drive calcium influx into nerve terminals, resulting in neurotransmitter release. Accordingly, the AP waveform is crucial in determining the timing and strength of synaptic transmission. The calyx of Held nerve terminals of rats of either sex showed minimum changes in AP waveform during high-frequency AP firing. We found that the stability of the calyceal AP waveform requires KCNQ (KV7) K1 channel activation during high-frequency spiking activity. High-frequency presynaptic spikes gradually led to accumulation of KCNQ channels in open states which kept interspike membrane potential sufficiently negative to maintain Na1 channel availability. Blocking KCNQ channels during stimulus trains led to inactivation of presynaptic Na1, and to a lesser extent KV1 channels, thereby reducing the AP amplitude and broadening AP duration. Moreover, blocking KCNQ channels disrupted the stable calcium influx and glutamate release required for reliable synaptic transmission at high frequency. Thus, while KCNQ channels are generally thought to prevent hyperactivity of neurons, we find that in axon terminals these channels function to facilitate reliable high-frequency synaptic signaling needed for sensory information processing.
AB - The presynaptic action potential (AP) is required to drive calcium influx into nerve terminals, resulting in neurotransmitter release. Accordingly, the AP waveform is crucial in determining the timing and strength of synaptic transmission. The calyx of Held nerve terminals of rats of either sex showed minimum changes in AP waveform during high-frequency AP firing. We found that the stability of the calyceal AP waveform requires KCNQ (KV7) K1 channel activation during high-frequency spiking activity. High-frequency presynaptic spikes gradually led to accumulation of KCNQ channels in open states which kept interspike membrane potential sufficiently negative to maintain Na1 channel availability. Blocking KCNQ channels during stimulus trains led to inactivation of presynaptic Na1, and to a lesser extent KV1 channels, thereby reducing the AP amplitude and broadening AP duration. Moreover, blocking KCNQ channels disrupted the stable calcium influx and glutamate release required for reliable synaptic transmission at high frequency. Thus, while KCNQ channels are generally thought to prevent hyperactivity of neurons, we find that in axon terminals these channels function to facilitate reliable high-frequency synaptic signaling needed for sensory information processing.
KW - KCNQ channels
KW - action potential waveform
KW - axon terminal
KW - calyx of Held
KW - channel inactivation
KW - synaptic transmission
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U2 - 10.1523/JNEUROSCI.0363-20.2022
DO - 10.1523/JNEUROSCI.0363-20.2022
M3 - Article
C2 - 35256530
AN - SCOPUS:85128800886
SN - 0270-6474
VL - 42
SP - 3305
EP - 3315
JO - Journal of Neuroscience
JF - Journal of Neuroscience
IS - 16
ER -