Developmental changes in calcium channel types mediating central synaptic transmission.
Multiple types of high-voltage-activated Ca(2+) channels trigger neurotransmitter release at the mammalian central synapse. Among them, the omega-conotoxin GVIA-sensitive N-type channels and the omega-Aga-IVA-sensitive P/Q-type channels mediate fast synaptic transmission. However, at most central synapses, it is not known whether the contributions of different Ca(2+) channel types to synaptic transmission remain stable throughout postnatal development. We have addressed this question by testing type-specific Ca(2+) channel blockers at developing central synapses. Our results indicate that N-type channels contribute to thalamic and cerebellar IPSCs only transiently during early postnatal period and P/Q-type channels predominantly mediate mature synaptic transmission, as we reported previously at the brainstem auditory synapse formed by the calyx of Held. In fact, Ca(2+) currents directly recorded from the auditory calyceal presynaptic terminal were identified as N-, P/Q-, and R-types at postnatal day 7 (P7) to P10 but became predominantly P/Q-type at P13. In contrast to thalamic and cerebellar IPSCs and brainstem auditory EPSCs, N-type Ca(2+) channels persistently contribute to cerebral cortical EPSCs and spinal IPSCs throughout postnatal months. Thus, in adult animals, synaptic transmission is predominantly mediated by P/Q-type channels at a subset of synapses and mediated synergistically by multiple types of Ca(2+) channels at other synapses.
Iwasaki
S
S
Department of Neurophysiology, University of Tokyo Faculty of Medicine, Tokyo 113-0033, Japan.
Momiyama
A
A
Uchitel
O D
OD
Takahashi
T
T
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000367:Age Factors; D000818:Animals; D001923:Brain Chemistry / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020864:Calcium Channels, N-Type / Q000502:physiology*; D020908:Calcium Channels, R-Type / Q000502:physiology; D002490:Central Nervous System / Q000737:chemistry / Q000254:growth & development* / Q000502:physiology; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D018684:Glycine Agents / Q000494:pharmacology; D009924:Organ Culture Techniques; D051381:Rats; D017208:Rats, Wistar; D013331:Strychnine / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology; D020867:omega-Agatoxin IVA / Q000494:pharmacology; D020960:omega-Conotoxins / Q000494:pharmacology
D015763:2-Amino-5-phosphonovalerate; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D002121:Calcium Channel Blockers; D020864:Calcium Channels, N-Type; D020908:Calcium Channels, R-Type; D018691:Excitatory Amino Acid Antagonists; D018684:Glycine Agents; D013331:Strychnine; D005680:gamma-Aminobutyric Acid; D020867:omega-Agatoxin IVA; D020960:omega-Conotoxins