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Abstract
The renin-angiotensin system is an enzymatic cascade by which angiotensinogen is cleaved by renin and then by angiotensin-converting enzyme to produce angiotensin II (Ang II) and subsequently other angiotensins. Biochemical and neurophysiological studies have documented the presence of the reninangiotensin system and specific Ang II receptors in the brain. Also, circulating Ang II can exert some of its actions, such as blood pressure control and body fluid homeostasis, through stimulation of Ang II receptors in the circumventricular organs that lack a normal blood-brain barrier. In addition to some of the post-synaptic effects of Ang II, recent studies have revealed that Ang II regulates synaptic transmission in several brain regions, especially the nucleus of the solitary tract, hypothalamic paraventricular nucleus, and hippocampus. This review summarizes emerging new evidence on the effect of brain Ang II on glutamatergic and GABAergic synaptic transmission. This previously unrecognized presynaptic action of Ang II is important for the control of neuronal excitability and many physiological functions including autonomic control, hormone secretion, and memory. Future research on the role of brain-derived Ang II and its receptors in synaptic transmission will further enhance our understanding of the cellular mechanisms of Ang II and the relationship between the renin-angiotensin system and brain functions.
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Affiliation(s)
- Hui-Lin Pan
- Department of Anesthesiology, Pennsylvania State University College of Medicine, Hershey 17033-0850, USA.
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Ogier M, Bricca G, Bader M, Bezin L. Locus Coeruleus Dysfunction in Transgenic Rats with Low Brain Angiotensinogen. CNS Neurosci Ther 2016; 22:230-7. [PMID: 26775713 DOI: 10.1111/cns.12488] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 10/30/2015] [Accepted: 10/30/2015] [Indexed: 12/25/2022] Open
Abstract
AIMS Transgenic TGR(ASrAOGEN)680 (TGR) rats with specific downregulation of glial angiotensinogen (AOGEN) synthesis develop cardiovascular deficits, anxiety, altered response to stress, and depression. Here, we evaluated whether these deficits are associated with alteration of the integrity of the noradrenergic system originating from locus coeruleus (LC) neurons. METHODS Adult TGR rats were compared to control Sprague Dawley rats in terms of the following: tissue levels of transcripts encoding noradrenergic markers, tissue tyrosine hydroxylase (TH) protein level, in vivo TH activity, density of TH-containing fibers, behavioral response to novelty, locomotor activity, and polysomnography. RESULTS TH expression was increased in the LC of TGR rats compared to controls. In LC terminal fields, there was an increase in density of TH-containing fibers in TGR rats that was associated with an elevation of in vivo TH activity. TGR rats also displayed locomotor hyperactivity in response to novelty. Moreover, polysomnographic studies indicated that daily paradoxical sleep duration was increased in TGR rats and that the paradoxical sleep rebound triggered by total sleep deprivation was blunted in these rats. CONCLUSIONS Altogether, these results suggest that disruption of astroglial AOGEN synthesis leads to cardiovascular, cognitive, behavioral, and sleep disorders that might be partly due to LC dysfunction.
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Affiliation(s)
- Michael Ogier
- INSERM U1028, CNRS UMR5292, University Claude Bernard Lyon 1, Lyon Neuroscience Research Center, Team TIGER, Lyon, France.,Institute for Epilepsy, IDEE, Lyon, France.,French Armed Forces Biomedical Research Institute, Bretigny-sur-Orge, France
| | | | - Michael Bader
- Max-Delbrück Center for Molecular Medicine, Berlin-Buch, Germany
| | - Laurent Bezin
- INSERM U1028, CNRS UMR5292, University Claude Bernard Lyon 1, Lyon Neuroscience Research Center, Team TIGER, Lyon, France.,Institute for Epilepsy, IDEE, Lyon, France
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Gomes CM, Donadio MVF, Franskoviaki I, Anselmo-Franci JA, Franci CR, Lucion AB, Sanvitto GL. Neonatal handling reduces angiotensin II receptor density in the medial preoptic area and paraventricular nucleus but not in arcuate nucleus and locus coeruleus of female rats. Brain Res 2006; 1067:177-80. [PMID: 16337927 DOI: 10.1016/j.brainres.2005.10.081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Revised: 10/20/2005] [Accepted: 10/20/2005] [Indexed: 11/25/2022]
Abstract
Neonatal handling alters the hypothalamic-pituitary-adrenal (HPA) axis and the hypothalamic-pituitary-gonads axis (HPG) in adult animals, and angiotensin II (Ang II) modulates the functions in these axes. We tested whether neonatal handling could change the density of Ang II receptors in some central areas in female rats. Results showed decreased density of the Ang II receptors in the medial preoptic area (MPOA) and hypothalamic paraventricular nucleus (PVN) of the neonatal handled group.
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Affiliation(s)
- Cármen Marilei Gomes
- Departamento de Fisiologia, Instituto de Ciências Básicas da Saúde (ICBS), Universidade Federal do Rio Grande do Sul (UFRGS), Rua Sarmento Leite 500, Porto Alegre, RS 90050-170, Brazil
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Donadio MVF, Gomes CM, Sagae SC, Franci CR, Anselmo-Franci JA, Lucion AB, Sanvitto GL. Angiotensin II receptors are upregulated by estradiol and progesterone in the locus coeruleus, median preoptic nucleus and subfornical organ of ovariectomized rats. Brain Res 2005; 1065:47-52. [PMID: 16297888 DOI: 10.1016/j.brainres.2005.10.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Revised: 10/03/2005] [Accepted: 10/11/2005] [Indexed: 11/20/2022]
Abstract
Angiotensin II (Ang II) receptors in specific brain areas and in the anterior pituitary are controlled by reproductive hormones. Since Ang II also plays a role in controlling reproductive functions, such as luteinizing hormone and prolactin secretion, the objective of the present study was to evaluate the regulation of Ang II receptors by estradiol (E(2)) and progesterone (P) in areas of the brain involved in homeostatic and reproductive functions, such as the locus coeruleus (LC), median preoptic nucleus (MnPO) and subfornical organ (SFO). Adult female rats were ovariectomized under anesthesia and divided into 2 groups after 2 weeks: OVX plus E(2)/P replacement (OVXE(2)P) and OVX plus oil vehicle (OVX). E(2) was injected for 3 consecutive days followed by an injection of P on the 4th day. Animals were killed by decapitation and the brains were removed and frozen. Consecutive coronal brain sections were cut in a cryostat and Ang II receptors were quantified by autoradiography in the MnPO, LC and SFO. Treatment of OVX rats with E(2) and P induced a significant increase in the Ang II receptor binding (fmol/mg protein) in the MnPO (OVX: 4.48 +/- 0.58 and OVXE(2)P: 9.89 +/- 1.65), LC (OVX: 2.72 +/- 0.37 and OVXE(2)P: 8.03 +/- 0.9) and SFO (OVX: 5.45 +/- 0.66 and OVXE(2)P: 10.73 +/- 1.79) compared to OVX animals treated with the vehicle, P < 0.05. In conclusion, these results show that Ang II receptors are upregulated by E(2) and P in the LC, MnPO and SFO of ovariectomized rats.
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Affiliation(s)
- Márcio Vinícius Fagundes Donadio
- Departamento de Fisiologia, Instituto de Ciências Básicas da Saúde, ICBS, Universidade Federal do Rio Grande do Sul, UFRGS, Sarmento Leite 500, Porto Alegre, RS 90050-170, Brazil
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Braszko JJ, Karwowska-Polecka W, Halicka D, Gard PR. Captopril and enalapril improve cognition and depressed mood in hypertensive patients. J Basic Clin Physiol Pharmacol 2005; 14:323-43. [PMID: 15198305 DOI: 10.1515/jbcpp.2003.14.4.323] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
UNLABELLED In this study, we evaluate the effects of two angiotensin converting enzyme inhibitors (ACEIs), captopril and enalapril given chronically as antihypertensive treatment, on certain cognitive and emotional processes in humans. Thirty-nine subjects with mild to moderate hypertension and fifteen normotensive controls were divided into four groups consisting of normotensive and hypertensive subjects taking captopril, enalapril, or no medication at all. The Rey Auditory Verbal Learning Test and the Wechsler Memory Scale were used to evaluate their cognitive functioning. Mood changes in all subjects were assessed using the Beck Depression Inventory and the Hopkins Symptom Check- list (HSC). RESULTS Untreated hypertensive patients scored lower than normotensive controls in cognitive tests and significantly worse in cumulative recall (P < 0.05) and paired words association (P < 0.01). When compared with normotensive subjects, untreated hypertensive patients also scored significantly higher on the depression with anxiety subscale in HSC (P < 0.05). No significant influence of hypertension was found in any other examined aspect of cognition and mood. In most cases captopril improved and enalapril reversed the adverse memory effects of hypertension. High arterial blood pressure is significantly associated with an impairment of cognition and the occurrence of depression with anxiety in humans. Enalapril and, to a lesser extent, captopril reversed these deficits.
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Affiliation(s)
- Jan J Braszko
- Department of Clinical Pharmacology, Medical University of Bialystok, Sklodowskiej 24a, 15276 Bialystok, Poland.
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Biomedical vignette. J Biomed Sci 2004. [DOI: 10.1007/bf02254431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Hwang BH, Chan P, Peters T. Angiotensin II receptor binding in the locus ceruleus of spontaneously hypertensive rats and Wistar-Kyoto rats: a quantitative autoradiographic study with references to hypertension and cardiac/testicular hypertrophy. J Biomed Sci 2004; 11:331-8. [PMID: 15067216 DOI: 10.1007/bf02254437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2003] [Accepted: 12/23/2003] [Indexed: 10/25/2022] Open
Abstract
The locus ceruleus (LC) contains a high density of angiotensin II (AII) receptors. The role of AII receptors at the LC in genetic hypertension and organ function is unclear. Spontaneously hypertensive (SHR) rats and Wistar-Kyoto (WKY) rats were studied, and blood pressure of animals was measured using the tail-cuff method. Animals were decapitated and the heart weight (HW) and testicular weight (TW) of animals measured. AII receptor binding was carried out by incubating the LC tissue sections with 200 pM [(125)I]-AII receptor ligand, and measured using quantitative autoradiography. Results showed that the HW/BW ratio was significantly higher in SHR rats than WKY rats. However, the TW/BW ratio was higher in SHR rats than WKY rats only at two hypertensive stages, whereas AII receptor binding capacity in the LC was also statistically higher in SHR rats than WKY rats. Results indicated that cardiac and testicular hypertrophies were related to higher AII receptor binding in the LC of SHR rats, when compared with WKY rats. Interestingly, the literature shows that there is an LC-testes axis. In conclusion, this study indicated that AII receptors in the LC are associated with genetic hypertension, and testicular weight could be a reasonable index for essential hypertension.
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Affiliation(s)
- Bang H Hwang
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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Dodge AH, Reid IA, Inagami T. Renin and angiotensin II receptor expression in the brains of DES-treated Syrian hamsters. Anat Rec (Hoboken) 1997; 248:442-6. [PMID: 9214562 DOI: 10.1002/(sici)1097-0185(199707)248:3<442::aid-ar17>3.0.co;2-p] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND The renin angiotensin system (RAS) promotes vasoconstriction. Expression of RAS is induced by different factors. METHODS In this study, forebrain sections of hamster brains were studied by immunohistochemical methods to determine the location of renin-positive and angiotensin II receptor-positive cells. The brain sections were obtained from diethylstilbesterol- (DES-) treated hamsters, adult non-DES-treated hamsters, elderly non-DES-treated hamsters, neonatal hamsters, and 15-day fetal hamsters. Circulating renin activity was determined for all but the neonatal and 15-day fetal hamsters. RESULTS Renin-positive and angiotensin II receptor-positive vascular smooth muscle cells were observed in DES-treated hamsters. No positive cells were observed in neonatal, 15-day fetal, and adult non-DES-treated hamsters. Some expression was observed in elderly hamsters. CONCLUSIONS Therefore, focal expression of the renin angiotensin system in brain vasculature was induced by the synthetic estrogen DES.
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Affiliation(s)
- A H Dodge
- Department of Basic Sciences, California College of Podiatric Medicine, San Francisco 94115, USA
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Reagan LP, Flanagan-Cato LM, Yee DK, Ma LY, Sakai RR, Fluharty SJ. Immunohistochemical mapping of angiotensin type 2 (AT2) receptors in rat brain. Brain Res 1994; 662:45-59. [PMID: 7859090 DOI: 10.1016/0006-8993(94)90794-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Recently developed antisera selective for angiotensin Type 2 (AT2) receptors were used to localize AT2 receptors in rat brain by immunohistochemistry. While the results from these experiments were largely consistent with previous autoradiographic and radioligand binding analyses of AT2 receptor populations in brain, there were also some notable differences in the distribution of immunoreactivity. More specifically, in agreement with previous studies, AT2 antisera detected apparent receptor populations in the locus coeruleus and the bed nucleus of the accessory olfactory tract, whereas AT2 receptor-immunoreactivity in the cerebellum was primarily associated with the Purkinje cell layer and the deep cerebellar nuclei rather than the molecular layer as has been previously reported in autoradiographic studies. Other regions with prominent immune-staining included all subfields of the hippocampus, which had been previously reported to contain exclusively AT1 receptors. Limbic structures such as the amygdala, thalamic areas such as the rhomboid thalamic nucleus, the paraventricular thalamic nucleus, hypothalamic areas such as the paraventricular hypothalamic nucleus, and the supraoptic nucleus also exhibited prominent AT2-immunoreactivity. In the paraventricular hypothalamic nucleus, AT2 receptor staining appeared to be associated primarily with the magnocellular neurons. In all regions examined, AT2 receptor immunoreactivity was associated with the cytoplasm and cell membrane and was not localized within the nucleus. Collectively, these results confirm and extend the neuroanatomical resolution of previous autoradiographic studies as well as identify new AT2 receptor populations in rat brain.
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Affiliation(s)
- L P Reagan
- Department of Animal Biology, University of Pennsylvania, Philadelphia 19104
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Xiong H, Marshall KC. Angiotensin II depresses glutamate depolarizations and excitatory postsynaptic potentials in locus coeruleus through angiotensin II subtype 2 receptors. Neuroscience 1994; 62:163-75. [PMID: 7816198 DOI: 10.1016/0306-4522(94)90322-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A previously reported depression of glutamate responses by angiotensin II was investigated to define the nature of this neuromodulatory effect. Studies were carried out in an vitro brain slice preparation containing the locus coeruleus, using intracellular recordings, and iontophoretic, micropressure and bath perfusion methods for application of drugs. The angiotensin action was found to be blocked by a non-peptide antagonist specific for the angiotensin type 2 receptor, and not by an antagonist selective for the type 1 receptor. Excitatory postsynaptic potentials mediated primarily by excitatory amino acids were also depressed by angiotensin II. The angiotensin II depressions of glutamate were shown to be strong and highly specific. The low effectiveness of bath-applied compared with iontophoretically or micropressure-applied angiotensin II was found to be at least partly explained by a rapid degradation by peptidases. Ammonium ions and hydrogen ions were also able to depress glutamate responses, but these effects were not specific for locus coeruleus neurons and were mediated independently of the angiotensin actions. Strong depression by angiotensin II of excitatory postsynaptic potentials as well as exogenously applied glutamate strengthens the strong possibility of a physiological role for this neuromodulatory mechanism. The identification of the type 2 angiotensin receptor subtype as the mediator of this effect indicates a novel functional role for this receptor, since previously recognized functions of angiotensin II in the brain, such as vascular and body fluid regulation, have been associated with the type 1 receptor.
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Affiliation(s)
- H Xiong
- Department of Physiology, Faculty of Medicine, University of Ottawa, Ontario, Canada
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