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Sandgren JA, Linggonegoro DW, Zhang SY, Sapouckey SA, Claflin KE, Pearson NA, Leidinger MR, Pierce GL, Santillan MK, Gibson-Corley KN, Sigmund CD, Grobe JL. Angiotensin AT 1A receptors expressed in vasopressin-producing cells of the supraoptic nucleus contribute to osmotic control of vasopressin. Am J Physiol Regul Integr Comp Physiol 2018; 314:R770-R780. [PMID: 29364700 PMCID: PMC6032302 DOI: 10.1152/ajpregu.00435.2017] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 01/03/2018] [Accepted: 01/17/2018] [Indexed: 11/22/2022]
Abstract
Angiotensin II (ANG) stimulates the release of arginine vasopressin (AVP) from the neurohypophysis through activation of the AT1 receptor within the brain, although it remains unclear whether AT1 receptors expressed on AVP-expressing neurons directly mediate this control. We explored the hypothesis that ANG acts through AT1A receptors expressed directly on AVP-producing cells to regulate AVP secretion. In situ hybridization and transgenic mice demonstrated localization of AVP and AT1A mRNA in the supraoptic nucleus (SON) and the paraventricular nucleus (PVN), but coexpression of both AVP and AT1A mRNA was only observed in the SON. Mice harboring a conditional allele for the gene encoding the AT1A receptor (AT1Aflox) were then crossed with AVP-Cre mice to generate mice that lack AT1A in all cells that express the AVP gene (AT1AAVP-KO). AT1AAVP-KO mice exhibited spontaneously increased plasma and serum osmolality but no changes in fluid or salt-intake behaviors, hematocrit, or total body water. AT1AAVP-KO mice exhibited reduced AVP secretion (estimated by measurement of copeptin) in response to osmotic stimuli such as acute hypertonic saline loading and in response to chronic intracerebroventricular ANG infusion. However, the effects of these receptors on AVP release were masked by complex stimuli such as overnight dehydration and DOCA-salt treatment, which simultaneously induce osmotic, volemic, and pressor stresses. Collectively, these data support the expression of AT1A in AVP-producing cells of the SON but not the PVN, and a role for AT1A receptors in these cells in the osmotic regulation of AVP secretion.
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MESH Headings
- Angiotensin II/administration & dosage
- Angiotensin II/pharmacology
- Animals
- Body Water
- Feeding Behavior
- Injections, Intraventricular
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Osmosis
- Paraventricular Hypothalamic Nucleus/metabolism
- Receptor, Angiotensin, Type 1/biosynthesis
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/physiology
- Sodium, Dietary
- Supraoptic Nucleus/metabolism
- Supraoptic Nucleus/physiology
- Vasoconstrictor Agents/administration & dosage
- Vasoconstrictor Agents/pharmacology
- Vasopressins/biosynthesis
- Vasopressins/physiology
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Affiliation(s)
| | | | - Shao Yang Zhang
- Department of Pharmacology, University of Iowa , Iowa City, Iowa
| | | | | | - Nicole A Pearson
- Department of Pharmacology, University of Iowa , Iowa City, Iowa
| | | | - Gary L Pierce
- Department of Health and Human Physiology, University of Iowa , Iowa City, Iowa
- Center for Hypertension Research, University of Iowa , Iowa City, Iowa
- François M. Abboud Cardiovascular Research Center, University of Iowa , Iowa City, Iowa
| | - Mark K Santillan
- Department of Obstetrics and Gynecology, University of Iowa , Iowa City, Iowa
- Center for Hypertension Research, University of Iowa , Iowa City, Iowa
| | - Katherine N Gibson-Corley
- Department of Pathology, University of Iowa , Iowa City, Iowa
- Center for Hypertension Research, University of Iowa , Iowa City, Iowa
- Fraternal Order of Eagles' Diabetes Research Center, University of Iowa , Iowa City, Iowa
| | - Curt D Sigmund
- Department of Pharmacology, University of Iowa , Iowa City, Iowa
- Center for Hypertension Research, University of Iowa , Iowa City, Iowa
- François M. Abboud Cardiovascular Research Center, University of Iowa , Iowa City, Iowa
| | - Justin L Grobe
- Department of Pharmacology, University of Iowa , Iowa City, Iowa
- Center for Hypertension Research, University of Iowa , Iowa City, Iowa
- François M. Abboud Cardiovascular Research Center, University of Iowa , Iowa City, Iowa
- Iowa Neuroscience Institute, University of Iowa , Iowa City, Iowa
- Obesity Research and Education Initiative, University of Iowa , Iowa City, Iowa
- Fraternal Order of Eagles' Diabetes Research Center, University of Iowa , Iowa City, Iowa
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Hayashi M, Arima H, Goto M, Banno R, Watanabe M, Sato I, Nagasaki H, Oiso Y. Vasopressin gene transcription increases in response to decreases in plasma volume, but not to increases in plasma osmolality, in chronically dehydrated rats. Am J Physiol Endocrinol Metab 2006; 290:E213-7. [PMID: 16144818 DOI: 10.1152/ajpendo.00158.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The synthesis of arginine vasopressin (AVP) in the magnocellular neurons of the supraoptic (SON) and paraventricular nuclei (PVN) is physiologically regulated by plasma osmolality and volume. To clarify how the regulation of AVP gene transcription is affected by chronic dehydration, we examined changes in the transcriptional activities of AVP gene by plasma osmolality and volume in both euhydrated and dehydrated conditions. Euhydrated rats had free access to water, whereas dehydrated rats had been deprived of water for 3 days before experiments. Rats in both conditions were subjected to acute hypertonic stimuli or hypovolemia, and changes in AVP heteronuclear (hn)RNA levels, an indicator of gene transcription, in the SON and PVN were examined with in situ hybridization. The intraperitoneal (i.p.) injection (2% body wt) of hypertonic (1.5 M) saline increased plasma Na levels by approximately 40 meq/l in both euhydrated and dehydrated conditions. However, expression levels of AVP hnRNA in the SON and PVN were increased only in euhydrated, not dehydrated, rats. On the other hand, i.p. injection of polyethylene glycol decreased the plasma volume by approximately 16-20%, and AVP hnRNA levels in the SON and PVN were significantly increased in both conditions. Thus it is demonstrated that signaling pathways regulating AVP gene transcription in the magnocellular neurons were completely refractory to acute osmotic stimuli under the chronic dehydration and that AVP gene transcription could probably respond to acute hypovolemia through different intracellular signal transduction pathways from those for osmoregulation.
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Affiliation(s)
- Masayuki Hayashi
- Dept. of Endocrinology and Diabetes, Nagoya Univ. Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
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Kondo N, Arima H, Banno R, Kuwahara S, Sato I, Oiso Y. Osmoregulation of vasopressin release and gene transcription under acute and chronic hypovolemia in rats. Am J Physiol Endocrinol Metab 2004; 286:E337-46. [PMID: 14613925 DOI: 10.1152/ajpendo.00328.2003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although acute decreases in plasma volume are known to enhance the osmotically induced arginine vasopressin (AVP) release, it is unclear whether there is also such interaction at the level of gene transcription. It also remains to be established how sustained changes in plasma volume affect the osmoregulation. In this study, we examined how acute and chronic decreases in blood volume affected the osmoregulation of AVP release and gene transcription in rats. Acute hypovolemia was induced by intraperitoneal injection of polyethylene glycol (PEG), and chronic hypovolemia was induced by 3 days of water deprivation (WD) or 12 days of salt loading (SL). Rats were injected with isotonic or hypertonic saline, and plasma AVP levels and AVP heteronuclear (hn)RNA expression in the supraoptic and paraventricular nuclei, an indicator of gene transcription, were examined in relation to plasma osmolality in each group. Plasma AVP levels were correlated with plasma Na levels in all groups. Whereas the regression lines relating plasma AVP to Na were almost identical among control, WD, and SL groups, the thresholds of plasma Na for AVP release were significantly decreased only in the PEG group. AVP hnRNA levels were also correlated with plasma Na levels in control and PEG groups, and the thresholds were significantly decreased in the PEG group. In contrast, there was no significant correlation of AVP hnRNA and plasma Na levels in WD and SL groups. Thus it was demonstrated that acute and chronic reduction in plasma volume affected the osmoregulation of AVP release and gene transcription in different ways.
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Affiliation(s)
- Noriko Kondo
- Department of Metabolic Diseases, Field of Internal Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
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