title: Differences in acid-induced currents between oxytocin-mRFP1 and vasopressin-eGFP neurons isolated from the supraoptic and paraventricular nuclei of transgenic rats.
abstract: The hypothalamic supraoptic nucleus (SON) and paraventricular nucleus (PVN) consists of two types of magnocellular neurosecretory cells, oxytocin (OXT) and arginine vasopressin (AVP). We generated and characterized rats that express an OXT-monomeric red fluorescent protein 1 (mRFP1) and an AVP-enhanced green fluorescent protein (eGFP) fusion transgene. These transgenic rats enable the visualization of OXT or AVP neurons. Taking advantage of this, we examined the differences between OXT-mRFP1 neurons and AVP-eGFP neurons in response to acid. Acid-sensing ion channels (ASICs) are neuronal voltage-insensitive cationic channels that are activated by extracellular acidification. Although functional ASICs have been identified in AVP neurons, differences in acid-induced currents between OXT and AVP neurons in SON have not been reported. In the present study, we used the whole-cell patch-clamp technique to investigate differences between OXT-mRFP1 neurons and AVP-eGFP neurons reaction to acid in SON and PVN. In voltage clamp mode, lowering extracellular pH evoked inward currents in both OXT-mRFP1 neurons and AVP-eGFP neurons. In our findings, the acid-induced currents in the OXT-mRFP1 neurons were significantly smaller than those in the AVP-eGFP neurons. These acid-induced currents were inhibited by amiloride, a known blocker of ASICs. Further, to compare the response to acid between OXT-mRFP1 and AVP-eGFP neurons in the same transgenic rat, we used a double transgenic rat by mating an OXT-mRFP1 transgenic rat with an AVP-eGFP transgenic rat. The acid-induced currents of OXT-mRFP1 neurons were significantly smaller than those of AVP-eGFP neurons from the double transgenic rats. These currents were almost completely inhibited by amiloride. The difference of acid-sensitivity between OXT and AVP neurons might contribute to maintaining systematic order in hypothalamic function.
authors.affiliation: Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan; Department of Otorhinolaryngology-Head and Neck Surgery, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan.
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Ohkubo
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan.
authors.forename: Toyoaki
authors.initials: T
authors.lastname: Ohbuchi
authors.affiliation: Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Yoshimura
authors.affiliation: Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Maruyama
authors.affiliation: Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Hashimoto
authors.affiliation: Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Matsuura
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Suzuki
authors.affiliation: Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan. Electronic address: yoichi@med.uoeh-u.ac.jp.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Ueta
mesh_terms: D062646:Acid Sensing Ion Channel Blockers / Q000494:pharmacology; D062565:Acid Sensing Ion Channels / Q000378:metabolism*; D017738:Alkanesulfonic Acids / Q000494:pharmacology; D000818:Animals; D001127:Arginine Vasopressin / Q000235:genetics / Q000378:metabolism*; D002021:Buffers; D002478:Cells, Cultured; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D009474:Neurons / Q000378:metabolism*; D010121:Oxytocin / Q000235:genetics / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D055647:Rats, Transgenic; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013495:Supraoptic Nucleus / Q000378:metabolism*; D000097573:Red Fluorescent Protein
chemical_list: D062646:Acid Sensing Ion Channel Blockers; D062565:Acid Sensing Ion Channels; D017738:Alkanesulfonic Acids; D001127:Arginine Vasopressin; D002021:Buffers; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D009025:Morpholines; D010121:Oxytocin; D011993:Recombinant Fusion Proteins; D000097573:Red Fluorescent Protein; C485184:enhanced green fluorescent protein; C004550:2-(N-morpholino)ethanesulfonic acid
keywords: Acid-sensing ion channels; Fluorescent protein; Oxytocin; PVN; SON; Vasopressin