Calcium channels triggering transmitter release in the rat medial superior olive

• Published in: Hearing research Vol. 162; no. 1; pp. 134 - 145
• Main Authors: Barnes-Davies, Margaret, Owens, Steven, Forsythe, Ian D.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.12.2001; Elsevier
• Subjects: Animals; Anterior ventral cochlear nucleus; Biological and medical sciences; Calcium Channels - classification; Calcium Channels - physiology; Cochlear Nucleus - metabolism; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Electric Conductivity; Electric Stimulation; Excitatory Postsynaptic Potentials; Fundamental and applied biological sciences. Psychology; Glutamate; Glycine; In Vitro Techniques; Medial nucleus of the trapezoid body; Medial superior olive; Neural Inhibition - physiology; Neurons - physiology; Neurotransmitter Agents - metabolism; Olivary Nucleus - cytology; Olivary Nucleus - metabolism; Olivary Nucleus - physiology; Rats; Rats, Inbred Strains; Synapses - physiology; Vertebrates: nervous system and sense organs; Voltage-gated calcium current; MNTB, medial nucleus of the trapezoid body; Voltage-gated calcium current; NMDA, N-methyl- D-aspartate; HVA, high voltage activated; Medial superior olive; Medial nucleus of the trapezoid body; IPSC, inhibitory postsynaptic current; aVCN, anterior ventral cochlear nucleus; MSO, medial superior olive; GABA, γ-aminobutyric acid; Glutamate; Glycine; ω-Aga IVA, ω-agatoxin IVA; AMPA, α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid; Anterior ventral cochlear nucleus; TTX, tetrodotoxin; CNQX, cyano-nitroquinoxaline-dione; ω-CTx GVIA, ω-conotoxin GVIA; aCSF, artificial cerebrospinal fluid; AP5, aminophosphonopentanoic acid; EPSC, excitatory postsynaptic current; Medial superior olivary nucleus; Calcium; Rat; Rodentia; Central nervous system; Ryanodine receptor; Electrophysiology; Auditory nucleus; Ionic channel; Ionic current; Superior olivary complex; Ventral cochlear nucleus; Medial nucleus of trapezoid body; Vertebrata; Mammalia; Synaptic transmission; Excitatory aminoacid; Neurotransmitter; Auditory pathway; Release; Brain (vertebrata)
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/S0378-5955(01)00378-1

We used whole cell voltage clamp recordings from neurones in rat auditory brainstem slices to study the Ca 2+ channel types involved in triggering synaptic glutamate and glycine release in the medial superior olivary nucleus. Glutamate release from the anterior ventral cochlear (aVCN) bushy neurone synapse did not involve L-type Ca 2+ channels (α 1C–D; Ca V1.2–1.3), but was mediated with similar efficacies by both N-type (α 1B; Ca V2.2) and the P/Q-type Ca 2+ channels (α 1A; Ca V2.1). Glycine release from the medial nucleus of the trapezoid body (MNTB) synapse was mediated predominantly by P/Q-type Ca 2+ channels, but with a significant contribution from N-type Ca 2+ channels. Combined application of the P/Q- and N-type Ca 2+ channel toxins, ω-agatoxin IVA and ω-conotoxin GVIA, left a very small remnant of both the inhibitory and excitatory postsynaptic currents, probably reflecting a minimal contribution of R-type Ca 2+ channels (α 1E; Ca V2.3) to transmitter release. In contrast with aVCN bushy neurones, MNTB somata lacked both T- (α 1G–I; Ca V3.1–3.3) and L-type channels, but expressed a higher proportion of P/Q-type Ca 2+ channels.