title: Molecular characterization of T-type Ca(2+) channels responsible for low threshold spikes in hypothalamic paraventricular nucleus neurons.
abstract: The hypothalamic paraventricular nucleus (PVN) is composed of functionally heterogeneous cell groups, possessing distinct electrophysiological properties depending on their functional roles. Previously, T-type Ca(2+) dependent low-threshold spikes (LTS) have been demonstrated in various PVN neuronal types, including preautonomic cells. However, the molecular composition and functional properties of the underlying T-type Ca(2+) channels have not been characterized. In the present study, we combined single cell reverse transcription-polymerase chain reaction (RT-PCR), immunohistochemistry and patch-clamp recordings to identify subtypes of T-type Ca(2+) channels expressed in PVN cells displaying LTS (PVN-LTS), including identified preautonomic neurons. LTS appeared at the end of hyperpolarizing pulses either as long-lasting plateaus or as short-lasting depolarizing humps. LTS were mediated by rapidly activating and inactivating T-type Ca(2+) currents and were blocked by Ni(2+). Single cell RT-PCR and immunohistochemical studies revealed Cav3.1 (voltage-gated Ca(2+) channel) as the main channel subunit detected in PVN-LTS neurons. In conclusion, these data indicate that Cav3.1 is the major subtype of T-type Ca(2+) channel subunit that mediates T-type Ca(2+) dependent LTS in PVN neurons.
authors.affiliation: Laboratory of Veterinary Pharmacology, Seoul National University, Kwanak-Gu, Seoul, South Korea. leeso@snu.ac.kr
authors.forename: S
authors.initials: S
authors.lastname: Lee
authors.forename: T H
authors.initials: TH
authors.lastname: Han
authors.forename: P M
authors.initials: PM
authors.lastname: Sonner
authors.forename: J E
authors.initials: JE
authors.lastname: Stern
authors.forename: P D
authors.initials: PD
authors.lastname: Ryu
authors.forename: S Y
authors.initials: SY
authors.lastname: Lee
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001931:Brain Mapping; D020747:Calcium Channels, T-Type / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D002772:Cholera Toxin / Q000378:metabolism; D004347:Drug Interactions; D004558:Electric Stimulation / Q000379:methods; D066298:In Vitro Techniques; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D009532:Nickel / Q000494:pharmacology; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D026941:Sodium Channel Blockers / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D020747:Calcium Channels, T-Type; D026941:Sodium Channel Blockers; D013779:Tetrodotoxin; D009532:Nickel; D002772:Cholera Toxin