Full-length transient receptor potential vanilloid 1 channels mediate calcium signals and possibly contribute to osmoreception in vasopressin neurones in the rat supraoptic nucleus

Autor: Oksana Forostyak, Tomohiko Kayano, Atsushi Asano, Rina Shibasaki, Taiki Moriya, Momoko Ichimura, Izumi Shibuya, Nami Takebuchi, Alexei Verkhratsky, Naoki Kitamura, Yoshinao Z. Hosaka, Govindan Dayanithi
Přispěvatelé: Tottori University, Yamaguchi University [Yamaguchi], Czech Academy of Sciences [Prague] (CAS), University of Manchester [Manchester], Basque Foundation for Science (Ikerbasque), University of the Basque Country/Euskal Herriko Unibertsitatea (UPV/EHU), Mécanismes moléculaires dans les démences neurodégénératives (MMDN), Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de la Santé et de la Recherche Médicale (INSERM)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)
Jazyk: angličtina
Rok vydání: 2015
Předmět:
Zdroj: Cell Calcium
Cell Calcium, Elsevier, 2015, 57 (1), pp.25-37. ⟨10.1016/j.ceca.2014.11.003⟩
ISSN: 0143-4160
Popis: International audience; Neurones in the supraoptic nucleus (SON) of the hypothalamus possess intrinsic osmosensing mechanisms, which are lost in transient receptor potential vanilloid 1 (Trpv1)-knock-out mice. The molecular nature of the osmosensory mechanism in SON neurones is believed to be associated with the N-terminal splice variant of Trpv1, although their entire molecular structures have not been hitherto identified. In this study, we sought for TRPV1-related molecules and their function in the rat SON. We performed RT-PCR and immunohistochemistry to detect TRPV1-related molecules in the SON, and patch-clamp and imaging of the cytosolic Ca(2+) concentration ([Ca(2+)]i) to measure responses to osmolality changes and TRPV-related drugs in acutely dissociated SON neurones of rats. RT-PCR analysis revealed full-length Trpv1 and a new N-terminal splice variant, Trpv1_SON (LC008303) in the SON. Positive immunostaining was observed using an antibody against the N-terminal portion of TRPV1 in arginine vasopressin (AVP)-immunoreactive neurones, but not in oxytocin (OT)-immunoreactive neurones. Approximately 20% of SON neurones responded to mannitol (50 mM) with increased action potential firing, inward currents, and [Ca(2+)]i mobilization. Mannitol-induced responses were observed in AVP neurones isolated from AVP-eGFP transgenic rats and identified by GFP fluorescence, but not in OT neurones isolated from OT-mRFP transgenic rats and identified by RFP fluorescence. The mannitol-induced [Ca(2+)]i responses were reversibly blocked by the non-selective TRPV antagonist, ruthenium red (10 μM) and the TRPV1 antagonists, capsazepine (10 μM) and BCTC (10 μM). Although the TRPV1 agonist, capsaicin (100 nM) evoked no response at room temperature, it triggered cationic currents and [Ca(2+)]i elevation when the temperature was increased to 36°C. These results suggest that AVP neurones in the rat SON possess functional full-length TRPV1. Moreover, differences between the responses to capsaicin or hyperosmolality obtained in rat SON neurones and those obtained from dorsal root ganglion neurones or TRPV1-expressing cells indicate that the osmoreceptor expressed in the SON may be a heteromultimer in which TRPV1 is co-assembled with some other, yet unidentified, molecules.
Databáze: OpenAIRE
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