NeuroendocrinologyVasopressin(4-9) fragment activates V1a-type vasopressin receptor in rat supraoptic neuronesGouzènes, Laurent1; Dayanithi, Govindan1,2; Moos, Françoise C.1Author Information 1CNRS UPR-1055, Biologie des Neurones Endocrines, Centre de Pharmacologie Endocrinologie, 141, rue de la Cardonille, F-34094 Montpellier sedes 5, France 2Corresponding Autor: Govindan Dayanithi ACKNOWLEDGEMENTS: Our gratitude to Drs C. Barberis (INSERM U-469, Montpellier, France) and C. Serradeil-Le Gal (Sanofi Recherche, France) for the generous gift of SR 49059 and SR 121463A. We thank Dr Colin H. Brown, (University Medical School, Edinburgh, UK) and Drs Ph. Richard, M.G. Desarménien, N. Hussy and A. Rabié (CNRS UPR-9055, Montpellier, France) for critical reading. Received 23 March 1999; accepted 13 April 1999 NeuroReport: June 3rd, 1999 - Volume 10 - Issue 8 - p 1735-1739 Buy Abstract THE effect of vasopressin fragment 4–9 (AVP(4–9)) was investigated on freshly dissociated rat supraoptic neurones by measuring changes in intracellular calcium concentration ([Ca2+]i) using fura-2 microspectrofluorimetry. In 60% of neurones responding to vasopressin, AVP(4–9) induced a transient rise in [Ca2+]i that was dose-dependent in the concentration range 10 nM to 1 μM AVP(4–9) and strongly decreased in Ca2+-free buffer (84% inhibition). This [Ca2+]i response was completely and reversibly abolished by SR 49059 (10 nM), a specific V1a receptor antagonist, but not by SR 121463A, a specific V2 receptor antagonist. Our results demonstrate the presence of functional receptors activated by AVP(4–9) on vasopressin-sensitive neurones that possess the apparent pharmacological profile of the V1a-type vasopressin receptor. © 1999 Lippincott Williams & Wilkins, Inc.