title: Endogenous arginine vasopressin-positive retinal cells in arginine vasopressin-eGFP transgenic rats identified by immunohistochemistry and reverse transcriptase-polymerase chain reaction.
abstract: OBJECTIVE
  Recently, arginine vasopressin (AVP) has been revealed to have diverse functional roles in nervous tissues beyond that of a vasoconstrictor. Several previous studies have indicated the existence of AVP in the retina, but the source of AVP has not been determined. The objective of the present study was to address the question of whether retinal cells have the ability to synthesize endogenous AVP to act in a paracrine or autocrine manner.
  
  
  METHODS
  We used AVP-eGFP transgenic rats to find endogenous AVP-positive cells in the retina by immunohistochemistry with an AVP antibody and a GFP antibody. We also examined AVP mRNA and AVP receptor genes by reverse transcriptase (RT)-PCR of dissociated GFP-positive cells and whole retinas.
  
  
  RESULTS
  Endogenous AVP-positive cells were found in the ganglion cell layer and inner nuclear layer of the retina of AVP-eGFP transgenic rats by immunohistochemistry. As indicated by the results of RT-PCR of dissociated GFP-positive cells, these cells have the ability to synthesize endogenous AVP, as well as transgenic AVP-eGFP. In addition, the V1a and V1b AVP receptors were found in the wild-type rat retina by whole retina RT-PCR, but the V2 receptor was not detectable. In dissociated AVP-eGFP-positive cells, no AVP receptor was detected by RT-PCR. Moreover, AVP secretion was not detected by stimulation with a high potassium (50 mM) solution.
  
  
  CONCLUSIONS
  In the rat retina, we found retinal cells that have the ability to synthesize endogenous AVP, and that the retina possesses V1a and V1b AVP receptors. Taken together, these results suggest that the retina has an intrinsic AVP-synthesizing and -receiving mechanism that can operate in a paracrine manner via V1a and V1b receptors.
authors.affiliation: Department of Cell Physiology, National Institute for Physiological Sciences, 38 Nishigonaka, Myodaiji, Okazaki, Aichi, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Moritoh
authors.forename: Kaori
authors.initials: K
authors.lastname: Sato
authors.forename: Yasunobu
authors.initials: Y
authors.lastname: Okada
authors.forename: Amane
authors.initials: A
authors.lastname: Koizumi
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression / Q000502:physiology*; D049452:Green Fluorescent Proteins; D007150:Immunohistochemistry; D008297:Male; D019899:Paracrine Communication / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D051381:Rats; D055647:Rats, Transgenic; D017208:Rats, Wistar; D017483:Receptors, Vasopressin / Q000235:genetics / Q000378:metabolism*; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014662:Vasoconstrictor Agents / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D017483:Receptors, Vasopressin; D014662:Vasoconstrictor Agents; D001127:Arginine Vasopressin; D049452:Green Fluorescent Proteins