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Odongoo B, Ohara H, Ngarashi D, Kaneko T, Kunihiro Y, Mashimo T, Nabika T. Pathophysiological significance of Stim1 mutation in sympathetic response to stress and cardiovascular phenotypes in SHRSP/Izm: In vivo evaluation by creation of a novel gene knock-in rat using CRISPR/Cas9. Clin Exp Hypertens 2020; 43:34-41. [PMID: 32700574 DOI: 10.1080/10641963.2020.1797085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Genetic approach using rat congenic lines between SHRSP/Izm and WKY/Izm identified stromal interaction molecule 1 (Stim1), an essential component of store-operated Ca2+ entry (SOCE), as a promising candidate gene responsible for the exaggerated sympathetic response to stress in SHRSP. Since SHRSP has a nonsense mutation in Stim1 resulting in the expression of a truncated form of STIM1 that caused reduction of SOCE activity in primary cultured cerebral astrocytes, we created SHRSP/Izm knocked-in with the wild-type Stim1 (KI SHRSP) by the CRISPR/Cas9 method to investigate whether the functional recovery of STIM1 would mitigate sympatho-excitation to stress in vivo in SHRSP. No potential off-target nucleotide substitutions/deletions/insertions were found in KI SHRSP. Western blotting and fluorescent Ca2+ imaging of astrocytes confirmed wild-type STIM1 expression and restored SOCE activity in astrocytes from KI SHRSP, respectively. Blood pressure (BP) measured by the tail-cuff method at 12, 16, and 20 weeks of age did not significantly differ between SHRSP and KI SHRSP, while the heart rate of KI SHRSP at 16 and 20 weeks of age was significantly lower than that of age-matched SHRSP. Unexpectedly, the sympathetic response to stress (evaluated with urinary excretion of norepinephrine under cold stress and BP elevation under cold/restraint stress) did not significantly differ between SHRSP and KI SHRSP. The present results indicated that the functional deficit of STIM1 was not a genetic determinant of the exaggerated sympathetic response to stress in SHRSP and that it would be necessary to explore other candidates within the congenic fragment on chromosome 1.
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Affiliation(s)
- Batbayar Odongoo
- Department of Functional Pathology, Faculty of Medicine, Shimane University , Izumo, Japan
| | - Hiroki Ohara
- Department of Functional Pathology, Faculty of Medicine, Shimane University , Izumo, Japan
| | - Davis Ngarashi
- Department of Functional Pathology, Faculty of Medicine, Shimane University , Izumo, Japan.,Department of Physiology, School of Medicine, Muhimbili University of Health and Allied Sciences , Dar Es Salaam, Tanzania
| | - Takehito Kaneko
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University , Kyoto, Japan.,Laboratory of Animal Reproduction and Development, Faculty of Science and Engineering, Iwate University , Morioka, Japan
| | - Yayoi Kunihiro
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University , Kyoto, Japan.,Institute of Experimental Animal Sciences, Graduate School of Medicine, Osaka University , Osaka, Japan
| | - Tomoji Mashimo
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University , Kyoto, Japan.,Institute of Experimental Animal Sciences, Graduate School of Medicine, Osaka University , Osaka, Japan.,Laboratory Animal Research Center, the Institute of Medical Science, The University of Tokyo , Tokyo, Japan
| | - Toru Nabika
- Department of Functional Pathology, Faculty of Medicine, Shimane University , Izumo, Japan
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Oshima N, Onimaru H, Matsubara H, Uchida T, Watanabe A, Imakiire T, Nishida Y, Kumagai H. Direct effects of glucose, insulin, GLP-1, and GIP on bulbospinal neurons in the rostral ventrolateral medulla in neonatal wistar rats. Neuroscience 2017; 344:74-88. [PMID: 28062192 DOI: 10.1016/j.neuroscience.2016.12.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 12/19/2016] [Accepted: 12/22/2016] [Indexed: 12/11/2022]
Abstract
Although patients with diabetes mellitus (DM) often exhibit hypertension, the mechanisms responsible for this correlation are not well known. We hypothesized that the bulbospinal neurons in the rostral ventrolateral medulla (RVLM) are affected by the levels of glucose, insulin, or incretins (glucagon like peptide-1 [GLP-1] or glucose-dependent insulinotropic peptide [GIP]) in patients with DM. To investigate whether RVLM neurons are activated by glucose, insulin, GLP-1, or GIP, we examined changes in the membrane potentials of bulbospinal RVLM neurons using whole-cell patch-clamp technique during superfusion with various levels of glucose or these hormones in neonatal Wistar rats. A brainstem-spinal cord preparation was used for the experiments. A low level of glucose stimulated bulbospinal RVLM neurons. During insulin superfusion, almost all the RVLM neurons were depolarized, while during GLP-1 or GIP superfusion, almost all the RVLM neurons were hyperpolarized. Next, histological examinations were performed to examine transporters for glucose and receptors for insulin, GLP-1, and GIP on RVLM neurons. Low-level glucose-depolarized RVLM neurons exhibited the presence of glucose transporter 3 (GLUT3). Meanwhile, insulin-depolarized, GLP-1-hyperpolarized, and GIP-hyperpolarized RVLM neurons showed each of the respective specific receptor. These results indicate that a low level of glucose stimulates bulbospinal RVLM neurons via specific transporters on these neurons, inducing hypertension. Furthermore, an increase in insulin or a reduction in incretins may also activate the sympathetic nervous system and induce hypertension by activating RVLM neurons via their own receptors.
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Affiliation(s)
- Naoki Oshima
- Department of Nephrology and Endocrinology, National Defense Medical College, Tokorozawa, Saitama, Japan.
| | - Hiroshi Onimaru
- Department of Physiology, Showa University School of Medicine, Tokyo, Japan
| | - Hidehito Matsubara
- Department of Nephrology and Endocrinology, National Defense Medical College, Tokorozawa, Saitama, Japan
| | - Takahiro Uchida
- Department of Nephrology and Endocrinology, National Defense Medical College, Tokorozawa, Saitama, Japan
| | - Atsushi Watanabe
- Department of Nephrology and Endocrinology, National Defense Medical College, Tokorozawa, Saitama, Japan
| | - Toshihiko Imakiire
- Department of Nephrology and Endocrinology, National Defense Medical College, Tokorozawa, Saitama, Japan
| | - Yasuhiro Nishida
- Department of Physiology, National Defense Medical College, Tokorozawa, Saitama, Japan
| | - Hiroo Kumagai
- Department of Nephrology and Endocrinology, National Defense Medical College, Tokorozawa, Saitama, Japan
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Guyenet PG, Stornetta RL, Bochorishvili G, Depuy SD, Burke PGR, Abbott SBG. C1 neurons: the body's EMTs. Am J Physiol Regul Integr Comp Physiol 2013; 305:R187-204. [PMID: 23697799 DOI: 10.1152/ajpregu.00054.2013] [Citation(s) in RCA: 205] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The C1 neurons reside in the rostral and intermediate portions of the ventrolateral medulla (RVLM, IVLM). They use glutamate as a fast transmitter and synthesize catecholamines plus various neuropeptides. These neurons regulate the hypothalamic pituitary axis via direct projections to the paraventricular nucleus and regulate the autonomic nervous system via projections to sympathetic and parasympathetic preganglionic neurons. The presympathetic C1 cells, located in the RVLM, are probably organized in a roughly viscerotopic manner and most of them regulate the circulation. C1 cells are variously activated by hypoglycemia, infection or inflammation, hypoxia, nociception, and hypotension and contribute to most glucoprivic responses. C1 cells also stimulate breathing and activate brain stem noradrenergic neurons including the locus coeruleus. Based on the various effects attributed to the C1 cells, their axonal projections and what is currently known of their synaptic inputs, subsets of C1 cells appear to be differentially recruited by pain, hypoxia, infection/inflammation, hemorrhage, and hypoglycemia to produce a repertoire of stereotyped autonomic, metabolic, and neuroendocrine responses that help the organism survive physical injury and its associated cohort of acute infection, hypoxia, hypotension, and blood loss. C1 cells may also contribute to glucose and cardiovascular homeostasis in the absence of such physical stresses, and C1 cell hyperactivity may contribute to the increase in sympathetic nerve activity associated with diseases such as hypertension.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908-0735, USA.
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Nabika T, Ohara H, Kato N, Isomura M. The stroke-prone spontaneously hypertensive rat: still a useful model for post-GWAS genetic studies? Hypertens Res 2012; 35:477-84. [PMID: 22399095 DOI: 10.1038/hr.2012.30] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The stroke-prone spontaneously hypertensive rat (SHRSP) is a unique genetic model of severe hypertension and cerebral stroke. SHRSP, as well as the spontaneously hypertensive rat, the parental strain of SHRSP, has made a tremendous contribution to cardiovascular research. However, the genetic mechanisms underlying hypertension and stroke in these rats have not yet been clarified. Recent studies using whole-genome sequencing and comprehensive gene expression analyses combined with classical quantitative trait loci analyses provided several candidate genes, such as Ephx2, Gstm1 and Slc34a1, which still need further evidence to define their pathological roles. Currently, genome-wide association studies can directly identify candidate genes for hypertension in the human genome. Thus, genetic studies in SHRSP and other rat models must be focused on the pathogenetic roles of 'networks of interacting genes' in hypertension, instead of searching for individual candidate genes.
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Affiliation(s)
- Toru Nabika
- Department of Functional Pathology, Shimane University School of Medicine, Izumo, Japan.
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Kumagai H, Oshima N, Matsuura T, Iigaya K, Imai M, Onimaru H, Sakata K, Osaka M, Onami T, Takimoto C, Kamayachi T, Itoh H, Saruta T. Importance of rostral ventrolateral medulla neurons in determining efferent sympathetic nerve activity and blood pressure. Hypertens Res 2011; 35:132-41. [PMID: 22170390 PMCID: PMC3273996 DOI: 10.1038/hr.2011.208] [Citation(s) in RCA: 123] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Accentuated sympathetic nerve activity (SNA) is a risk factor for cardiovascular events. In this review, we investigate our working hypothesis that potentiated activity of neurons in the rostral ventrolateral medulla (RVLM) is the primary cause of experimental and essential hypertension. Over the past decade, we have examined how RVLM neurons regulate peripheral SNA, how the sympathetic and renin-angiotensin systems are correlated and how the sympathetic system can be suppressed to prevent cardiovascular events in patients. Based on results of whole-cell patch-clamp studies, we report that angiotensin II (Ang II) potentiated the activity of RVLM neurons, a sympathetic nervous center, whereas Ang II receptor blocker (ARB) reduced RVLM activities. Our optical imaging demonstrated that a longitudinal rostrocaudal column, including the RVLM and the caudal end of ventrolateral medulla, acts as a sympathetic center. By organizing and analyzing these data, we hope to develop therapies for reducing SNA in our patients. Recently, 2-year depressor effects were obtained by a single procedure of renal nerve ablation in patients with essential hypertension. The ablation injured not only the efferent renal sympathetic nerves but also the afferent renal nerves and led to reduced activities of the hypothalamus, RVLM neurons and efferent systemic sympathetic nerves. These clinical results stress the importance of the RVLM neurons in blood pressure regulation. We expect renal nerve ablation to be an effective treatment for congestive heart failure and chronic kidney disease, such as diabetic nephropathy.
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Affiliation(s)
- Hiroo Kumagai
- Department of Nephrology, National Defense Medical College, Tokorozawa, Japan.
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Oshima N, Kumagai H, Iigaya K, Onimaru H, Kawai A, Nishida Y, Saruta T, Itoh H. Baro-excited neurons in the caudal ventrolateral medulla (CVLM) recorded using the whole-cell patch-clamp technique. Hypertens Res 2011; 35:500-6. [DOI: 10.1038/hr.2011.211] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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A 1.8-Mbp fragment on chromosome 1 affects sympathetic response to stress: evaluation in reciprocal congenic strains between stroke-prone spontaneously hypertensive rat and Wistar–Kyoto rat. J Hypertens 2011; 29:257-65. [DOI: 10.1097/hjh.0b013e32834137cd] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Allen AM. Role of angiotensin in the rostral ventrolateral medulla in the development and maintenance of hypertension. Curr Opin Pharmacol 2011; 11:117-23. [PMID: 21269877 DOI: 10.1016/j.coph.2010.12.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 12/13/2010] [Accepted: 12/23/2010] [Indexed: 02/07/2023]
Abstract
Whilst crucial for behavioural and homeostatic responses to environmental challenges, chronic elevation of sympathetic nervous system activity to specific vascular beds is associated with hypertension. Indeed such elevated activity may drive the increase in blood pressure seen in some people and in some experimental models of hypertension. This review discusses the neural circuitry involved in generating and modulating sympathetic efferent nerve activity, focusing on the premotor neurons of the rostral ventrolateral medulla. Neurons in the rostral ventrolateral medulla show altered responses to angiotensin II in experimental models of hypertension, suggesting that this might be an important node for interaction between these two systems that are crucial for regulation of blood pressure.
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Affiliation(s)
- Andrew M Allen
- Department of Physiology and Florey Neurosciences Institutes, University of Melbourne, Vic., 3010, Australia.
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Diurnal blood pressure variation, risk categories and antihypertensive treatment. Hypertens Res 2010; 33:767-71. [DOI: 10.1038/hr.2010.111] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Silvani A, Bastianini S, Berteotti C, Franzini C, Lenzi P, Lo Martire V, Zoccoli G. Central and baroreflex control of heart period during the wake-sleep cycle in consomic rats with different genetic susceptibility to hypertension. Clin Exp Pharmacol Physiol 2009; 37:322-7. [PMID: 19769608 DOI: 10.1111/j.1440-1681.2009.05293.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1. In spontaneously hypertensive rats (SHR), the contributions of the baroreflex and central autonomic commands to the control of heart period (HP) vary among wake-sleep states and are impaired during quiet wakefulness and rapid eye movement sleep (REMS), respectively. 2. Dahl salt-sensitive (SS) rats are genetically susceptible to salt-sensitive hypertension, the development of which depends on diet. Substitution of chromosome 13 of SS rats with that of Brown Norway rats confers salt-resistance to consomic SS-13BN rats. 3. In the present study, we tested whether differences in the central and baroreflex contributions to HP control occur among wake-sleep states in SS and SS-13BN rats and reflect genetic susceptibility to hypertension. Rats (n = 5 per group) were fed a prohypertensive diet late during development to minimize hypertension in SS rats and were instrumented with an arterial catheter and electrodes for discriminating wake-sleep states. 4. The cross-correlation function between HP and blood pressure indicated that, in SS and SS-13BN rats, the contributions of the baroreflex and central commands to the control of HP differed significantly among wake-sleep states, with central commands outweighing the baroreflex in REMS. However, these contributions did not differ significantly between SS and SS-13BN rats in any wake-sleep state. 5. The data suggest that differences in the central and baroreflex contributions to HP control among wake-sleep states, which have been demonstrated in SHR, can be generalized to other rat models used in hypertension research. Impairments in the baroreflex and central autonomic control of HP during quiet wakefulness and REMS, respectively, cannot be generalized as an index of genetic susceptibility to hypertension.
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Affiliation(s)
- Alessandro Silvani
- Department of Human and General Physiology, University of Bologna, Bologna, Italy
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Minoura Y, Onimaru H, Iigaya K, Homma I, Kobayashi Y. Electrophysiological responses of sympathetic preganglionic neurons to ANG II and aldosterone. Am J Physiol Regul Integr Comp Physiol 2009; 297:R699-706. [DOI: 10.1152/ajpregu.00041.2009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The intermediolateral cell column (IML) of the spinal cord is an important area where sympathetic impulses propagate to peripheral sympathetic organs. ANG II and aldosterone are important components of the renin-angiotensin-aldosterone system (RAAS), which activate the sympathetic nervous system. Each is partly synthesized in the brain and plays a paracrine role in the regulation of blood pressure independently of RAAS in the periphery. Our purpose in the present study was to clarify the contributions of sympathetic preganglionic neurons in the IML (IML neurons) and the effects of ANG II and aldosterone on the sympathetic nervous system. To examine responses to ANG II and aldosterone, we intracellularly recorded 104 IML neurons using a whole cell patch-clamp technique in spinal cord slice preparations. IML neurons were classified into two types: silent and firing. Both neuron types were significantly depolarized by ANG II, and candesartan inhibited this depolarization. After pretreatment with TTX, firing neurons (but not silent neurons) were significantly depolarized by ANG II. Aldosterone significantly increased the number of excitatory postsynaptic potentials (EPSPs) in both neuron types, but this response disappeared after pretreatment with TTX. ANG II and aldosterone had no synergistic effects on the IML neurons. The silent neurons had large cell soma, and many more dendrites than the firing neurons. These results suggest that ANG II acts presynaptically and postsynaptically in IML neurons, while aldosterone acts mainly presynaptically. Thus, the physiological effects of these substances are likely to be transmitted via specific membrane receptors of IML and/or presynaptic neurons.
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