1
|
Zhu D, Huang Y, Guo S, Li N, Yang X, Sui A, Wu Q, Zhang Y, Kong Y, Li Q, Zhang T, Zheng W, Li A, Yu J, Ma T, Li S. AQP4 Aggravates Cognitive Impairment in Sepsis-Associated Encephalopathy through Inhibiting Na v 1.6-Mediated Astrocyte Autophagy. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2205862. [PMID: 36922751 PMCID: PMC10190498 DOI: 10.1002/advs.202205862] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 02/24/2023] [Indexed: 05/18/2023]
Abstract
The pathology of sepsis-associated encephalopathy (SAE) is related to astrocyte-inflammation associated with aquaporin-4 (AQP4). The aim here is to investigate the effects of AQP4 associated with SAE and reveal its underlying mechanism causing cognitive impairment. The in vivo experimental results reveal that AQP4 in peripheral blood of patients with SAE is up-regulated, also the cortical and hippocampal tissue of cecal ligation and perforation (CLP) mouse brain has significant rise in AQP4. Furthermore, the data suggest that AQP4 deletion could attenuate learning and memory impairment, attributing to activation of astrocytic autophagy, inactivation of astrocyte and downregulate the expression of proinflammatory cytokines induced by CLP or lipopolysaccharide (LPS). Furthermore, the activation effect of AQP4 knockout on CLP or LPS-induced PPAR-γ inhibiting in astrocyte is related to intracellular Ca2+ level and sodium channel activity. Learning and memory impairment in SAE mouse model are attenuated by AQP4 knockout through activating autophagy, inhibiting neuroinflammation leading to neuroprotection via down-regulation of Nav 1.6 channels in the astrocytes. This results in the reduction of Ca2+ accumulation in the cell cytosol furthermore activating the inhibition of PPAR-γ signal transduction pathway in astrocytes.
Collapse
Affiliation(s)
- Dan‐Dan Zhu
- Department of PhysiologyCollege of Basic Medical SciencesLiaoning Provincial Key Laboratory of Cerebral DiseasesNational‐Local Joint Engineering Research Center for Drug‐Research and Development (R & D) of Neurodegenerative DiseasesDalian Medical UniversityDalian116044China
- Department of Critical Care Medicinethe Second Hospital of Dalian Medical UniversityDalian116023China
| | - Yue‐Lin Huang
- Department of PhysiologyCollege of Basic Medical SciencesLiaoning Provincial Key Laboratory of Cerebral DiseasesNational‐Local Joint Engineering Research Center for Drug‐Research and Development (R & D) of Neurodegenerative DiseasesDalian Medical UniversityDalian116044China
| | - Song‐Yu Guo
- Department of PhysiologyCollege of Basic Medical SciencesLiaoning Provincial Key Laboratory of Cerebral DiseasesNational‐Local Joint Engineering Research Center for Drug‐Research and Development (R & D) of Neurodegenerative DiseasesDalian Medical UniversityDalian116044China
| | - Na Li
- Department of PhysiologyCollege of Basic Medical SciencesLiaoning Provincial Key Laboratory of Cerebral DiseasesNational‐Local Joint Engineering Research Center for Drug‐Research and Development (R & D) of Neurodegenerative DiseasesDalian Medical UniversityDalian116044China
| | - Xue‐Wei Yang
- Department of PhysiologyCollege of Basic Medical SciencesLiaoning Provincial Key Laboratory of Cerebral DiseasesNational‐Local Joint Engineering Research Center for Drug‐Research and Development (R & D) of Neurodegenerative DiseasesDalian Medical UniversityDalian116044China
| | - Ao‐Ran Sui
- Department of PhysiologyCollege of Basic Medical SciencesLiaoning Provincial Key Laboratory of Cerebral DiseasesNational‐Local Joint Engineering Research Center for Drug‐Research and Development (R & D) of Neurodegenerative DiseasesDalian Medical UniversityDalian116044China
| | - Qiong Wu
- Department of PhysiologyCollege of Basic Medical SciencesLiaoning Provincial Key Laboratory of Cerebral DiseasesNational‐Local Joint Engineering Research Center for Drug‐Research and Development (R & D) of Neurodegenerative DiseasesDalian Medical UniversityDalian116044China
| | - Yue Zhang
- Department of PhysiologyCollege of Basic Medical SciencesLiaoning Provincial Key Laboratory of Cerebral DiseasesNational‐Local Joint Engineering Research Center for Drug‐Research and Development (R & D) of Neurodegenerative DiseasesDalian Medical UniversityDalian116044China
| | - Yue Kong
- Department of PhysiologyCollege of Basic Medical SciencesLiaoning Provincial Key Laboratory of Cerebral DiseasesNational‐Local Joint Engineering Research Center for Drug‐Research and Development (R & D) of Neurodegenerative DiseasesDalian Medical UniversityDalian116044China
| | - Qi‐Fa Li
- Department of PhysiologyCollege of Basic Medical SciencesLiaoning Provincial Key Laboratory of Cerebral DiseasesNational‐Local Joint Engineering Research Center for Drug‐Research and Development (R & D) of Neurodegenerative DiseasesDalian Medical UniversityDalian116044China
| | - Ting Zhang
- Department of PhysiologyCollege of Basic Medical SciencesLiaoning Provincial Key Laboratory of Cerebral DiseasesNational‐Local Joint Engineering Research Center for Drug‐Research and Development (R & D) of Neurodegenerative DiseasesDalian Medical UniversityDalian116044China
| | - Wen‐Fei Zheng
- Department of Critical Care Medicinethe Second Hospital of Dalian Medical UniversityDalian116023China
| | - Ai‐Ping Li
- Department of PhysiologyCollege of Basic Medical SciencesLiaoning Provincial Key Laboratory of Cerebral DiseasesNational‐Local Joint Engineering Research Center for Drug‐Research and Development (R & D) of Neurodegenerative DiseasesDalian Medical UniversityDalian116044China
| | - Jian Yu
- Department of Critical Care Medicinethe Second Hospital of Dalian Medical UniversityDalian116023China
| | - Tong‐Hui Ma
- School of MedicineNanjing University of Chinese MedicineNanjing210023China
| | - Shao Li
- Department of PhysiologyCollege of Basic Medical SciencesLiaoning Provincial Key Laboratory of Cerebral DiseasesNational‐Local Joint Engineering Research Center for Drug‐Research and Development (R & D) of Neurodegenerative DiseasesDalian Medical UniversityDalian116044China
| |
Collapse
|
2
|
Thompson JA, Miralles RM, Wengert ER, Wagley PK, Yu W, Wenker IC, Patel MK. Astrocyte reactivity in a mouse model of SCN8A epileptic encephalopathy. Epilepsia Open 2022; 7:280-292. [PMID: 34826216 PMCID: PMC9159254 DOI: 10.1002/epi4.12564] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 10/15/2021] [Accepted: 11/23/2021] [Indexed: 11/11/2022] Open
Abstract
OBJECTIVE SCN8A epileptic encephalopathy is caused predominantly by de novo gain-of-function mutations in the voltage-gated sodium channel Nav 1.6. The disorder is characterized by early onset of seizures and developmental delay. Most patients with SCN8A epileptic encephalopathy are refractory to current anti-seizure medications. Previous studies determining the mechanisms of this disease have focused on neuronal dysfunction as Nav 1.6 is expressed by neurons and plays a critical role in controlling neuronal excitability. However, glial dysfunction has been implicated in epilepsy and alterations in glial physiology could contribute to the pathology of SCN8A encephalopathy. In the current study, we examined alterations in astrocyte and microglia physiology in the development of seizures in a mouse model of SCN8A epileptic encephalopathy. METHODS Using immunohistochemistry, we assessed microglia and astrocyte reactivity before and after the onset of spontaneous seizures. Expression of glutamine synthetase and Nav 1.6, and Kir 4.1 channel currents were assessed in astrocytes in wild-type (WT) mice and mice carrying the N1768D SCN8A mutation (D/+). RESULTS Astrocytes in spontaneously seizing D/+ mice become reactive and increase expression of glial fibrillary acidic protein (GFAP), a marker of astrocyte reactivity. These same astrocytes exhibited reduced barium-sensitive Kir 4.1 currents compared to age-matched WT mice and decreased expression of glutamine synthetase. These alterations were only observed in spontaneously seizing mice and not before the onset of seizures. In contrast, microglial morphology remained unchanged before and after the onset of seizures. SIGNIFICANCE Astrocytes, but not microglia, become reactive only after the onset of spontaneous seizures in a mouse model of SCN8A encephalopathy. Reactive astrocytes have reduced Kir 4.1-mediated currents, which would impair their ability to buffer potassium. Reduced expression of glutamine synthetase would modulate the availability of neurotransmitters to excitatory and inhibitory neurons. These deficits in potassium and glutamate handling by astrocytes could exacerbate seizures in SCN8A epileptic encephalopathy. Targeting astrocytes may provide a new therapeutic approach to seizure suppression.
Collapse
Affiliation(s)
- Jeremy A. Thompson
- Department of AnesthesiologyUniversity of Virginia Health SystemCharlottesvilleVAUSA
- Neuroscience Graduate ProgramUniversity of VirginiaCharlottesvilleVAUSA
| | - Raquel M. Miralles
- Department of AnesthesiologyUniversity of Virginia Health SystemCharlottesvilleVAUSA
- Neuroscience Graduate ProgramUniversity of VirginiaCharlottesvilleVAUSA
| | - Eric R. Wengert
- Department of AnesthesiologyUniversity of Virginia Health SystemCharlottesvilleVAUSA
- Neuroscience Graduate ProgramUniversity of VirginiaCharlottesvilleVAUSA
| | - Pravin K. Wagley
- Department of AnesthesiologyUniversity of Virginia Health SystemCharlottesvilleVAUSA
| | - Wenxi Yu
- Department of Human GeneticsUniversity of MichiganAnn ArborMIUSA
| | - Ian C. Wenker
- Department of AnesthesiologyUniversity of Virginia Health SystemCharlottesvilleVAUSA
| | - Manoj K. Patel
- Department of AnesthesiologyUniversity of Virginia Health SystemCharlottesvilleVAUSA
- Neuroscience Graduate ProgramUniversity of VirginiaCharlottesvilleVAUSA
| |
Collapse
|
3
|
Tong L, Xing M, Wu J, Zhang S, Chu D, Zhang H, Chen F, Du D. Overexpression of NaV1.6 in the rostral ventrolateral medulla in rats mediates stress-induced hypertension via glutamate regulation. Clin Exp Hypertens 2022; 44:134-145. [PMID: 34994674 DOI: 10.1080/10641963.2021.2007942] [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: 11/03/2022]
Abstract
BACKGROUND The rostral ventrolateral medulla (RVLM) plays a key role in mediating the development of stress-induced hypertension (SIH). Furthermore, enhanced glutamate transport within glutamatergic neurons in the RVLM mediates pressor responses. Data from our previous studies suggest that the voltage-gated sodium channel NaV1.6 is overexpressed in neurons in the RVLM in SIH model rats and participates in the resulting elevation of blood pressure. However, previous studies have not investigated the relationship between NaV1.6 expression and glutamatergic neurons. METHODS Here, we constructed an SIH rat model by knocking down NaV1.6 via microinjection of clustered regularly interspaced short palindromic repeats (CRISPR) guide RNA into the RVLM. Glutamate-related markers were quantified by Western blotting and immunofluorescence, and blood pressure was measured in the rats. RESULTS Our findings showed that vesicular glutamate transporter 1 (VGluT1) protein expression in the RVLM was higher in SIH rats than in Control rats, and GAD67 protein expression in SIH rats was lower than that in Control rats. Therefore, the number of VGluT1-positive neurons increased, while the number of GAD67-labeled neurons decreased after stress. After knocking down NaV1.6 expression in the RVLM, VGluT1 expression and the number of VGluT1-positive neurons decreased relative to those in SIH rats, while GAD67 protein expression and the number of GAD67-labeled neurons increased relative to those in SIH rats. CONCLUSIONS These results indicate that overexpression of NaV1.6 in the RVLM may mediate the transport and transformation of glutamate in neurons, and NaV1.6 may participate in SIH.
Collapse
Affiliation(s)
- Lei Tong
- College of Life Science, Shanghai University, Shanghai, China
| | - Mengyu Xing
- College of Life Science, Shanghai University, Shanghai, China
| | - Jiaxiang Wu
- College of Life Science, Shanghai University, Shanghai, China
| | - Shuai Zhang
- International Cooperation Laboratory of Molecular Medicine, Academy of Chinese Medical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
| | - Dechang Chu
- College of Agriculture and Bioengineering, Heze University, Heze, China
| | - Haili Zhang
- College of Agriculture and Bioengineering, Heze University, Heze, China
| | - Fuxue Chen
- College of Life Science, Shanghai University, Shanghai, China
| | - Dongshu Du
- College of Life Science, Shanghai University, Shanghai, China.,College of Agriculture and Bioengineering, Heze University, Heze, China
| |
Collapse
|
4
|
Yao LL, Yuan S, Wu ZN, Luo JY, Tang XR, Tang CZ, Cui S, Xu NG. Contralateral S1 function is involved in electroacupuncture treatment-mediated recovery after focal unilateral M1 infarction. Neural Regen Res 2021; 17:1310-1317. [PMID: 34782576 PMCID: PMC8643050 DOI: 10.4103/1673-5374.327355] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Acupuncture at acupoints Baihui (GV20) and Dazhui (GV14) has been shown to promote functional recovery after stroke. However, the contribution of the contralateral primary sensory cortex (S1) to recovery remains unclear. In this study, unilateral local ischemic infarction of the primary motor cortex (M1) was induced by photothrombosis in a mouse model. Electroacupuncture (EA) was subsequently performed at acupoints GV20 and GV14 and neuronal activity and functional connectivity of contralateral S1 and M1 were detected using in vivo and in vitro electrophysiological recording techniques. Our results showed that blood perfusion and neuronal interaction between contralateral M1 and S1 is impaired after unilateral M1 infarction. Intrinsic neuronal excitability and activity were also disturbed, which was rescued by EA. Furthermore, the effectiveness of EA treatment was inhibited after virus-mediated neuronal ablation of the contralateral S1. We conclude that neuronal activity of the contralateral S1 is important for EA-mediated recovery after focal M1 infarction. Our study provides insight into how the S1–M1 circuit might be involved in the mechanism of EA treatment of unilateral cerebral infarction. The animal experiments were approved by the Committee for Care and Use of Research Animals of Guangzhou University of Chinese Medicine (approval No. 20200407009) April 7, 2020.
Collapse
Affiliation(s)
- Lu-Lu Yao
- South China Research Center for Acupuncture and Moxibustion, Medical College of Acupuncture Moxibustion and Rehabilitation, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong Province, China
| | - Si Yuan
- South China Research Center for Acupuncture and Moxibustion, Medical College of Acupuncture Moxibustion and Rehabilitation, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong Province, China
| | - Zhen-Nan Wu
- South China Research Center for Acupuncture and Moxibustion, Medical College of Acupuncture Moxibustion and Rehabilitation, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong Province, China
| | - Jian-Yu Luo
- South China Research Center for Acupuncture and Moxibustion, Medical College of Acupuncture Moxibustion and Rehabilitation, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong Province, China
| | - Xiao-Rong Tang
- South China Research Center for Acupuncture and Moxibustion, Medical College of Acupuncture Moxibustion and Rehabilitation, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong Province, China
| | - Chun-Zhi Tang
- South China Research Center for Acupuncture and Moxibustion, Medical College of Acupuncture Moxibustion and Rehabilitation, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong Province, China
| | - Shuai Cui
- South China Research Center for Acupuncture and Moxibustion, Medical College of Acupuncture Moxibustion and Rehabilitation, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong Province; Research Institute of Acupuncture and Meridian, Anhui University of Chinese Medicine, Hefei, Anhui Province, China
| | - Neng-Gui Xu
- South China Research Center for Acupuncture and Moxibustion, Medical College of Acupuncture Moxibustion and Rehabilitation, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong Province, China
| |
Collapse
|
5
|
Zybura A, Hudmon A, Cummins TR. Distinctive Properties and Powerful Neuromodulation of Na v1.6 Sodium Channels Regulates Neuronal Excitability. Cells 2021; 10:cells10071595. [PMID: 34202119 PMCID: PMC8307729 DOI: 10.3390/cells10071595] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 06/20/2021] [Accepted: 06/21/2021] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated sodium channels (Navs) are critical determinants of cellular excitability. These ion channels exist as large heteromultimeric structures and their activity is tightly controlled. In neurons, the isoform Nav1.6 is highly enriched at the axon initial segment and nodes, making it critical for the initiation and propagation of neuronal impulses. Changes in Nav1.6 expression and function profoundly impact the input-output properties of neurons in normal and pathological conditions. While mutations in Nav1.6 may cause channel dysfunction, aberrant changes may also be the result of complex modes of regulation, including various protein-protein interactions and post-translational modifications, which can alter membrane excitability and neuronal firing properties. Despite decades of research, the complexities of Nav1.6 modulation in health and disease are still being determined. While some modulatory mechanisms have similar effects on other Nav isoforms, others are isoform-specific. Additionally, considerable progress has been made toward understanding how individual protein interactions and/or modifications affect Nav1.6 function. However, there is still more to be learned about how these different modes of modulation interact. Here, we examine the role of Nav1.6 in neuronal function and provide a thorough review of this channel’s complex regulatory mechanisms and how they may contribute to neuromodulation.
Collapse
Affiliation(s)
- Agnes Zybura
- Program in Medical Neuroscience, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA;
- Biology Department, School of Science, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Andy Hudmon
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA;
| | - Theodore R. Cummins
- Program in Medical Neuroscience, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA;
- Biology Department, School of Science, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
- Correspondence:
| |
Collapse
|
6
|
Zybura AS, Baucum AJ, Rush AM, Cummins TR, Hudmon A. CaMKII enhances voltage-gated sodium channel Nav1.6 activity and neuronal excitability. J Biol Chem 2020; 295:11845-11865. [PMID: 32611770 DOI: 10.1074/jbc.ra120.014062] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/30/2020] [Indexed: 11/06/2022] Open
Abstract
Nav1.6 is the primary voltage-gated sodium channel isoform expressed in mature axon initial segments and nodes, making it critical for initiation and propagation of neuronal impulses. Thus, Nav1.6 modulation and dysfunction may have profound effects on input-output properties of neurons in normal and pathological conditions. Phosphorylation is a powerful and reversible mechanism regulating ion channel function. Because Nav1.6 and the multifunctional Ca2+/CaM-dependent protein kinase II (CaMKII) are independently linked to excitability disorders, we sought to investigate modulation of Nav1.6 function by CaMKII signaling. We show that inhibition of CaMKII, a Ser/Thr protein kinase associated with excitability, synaptic plasticity, and excitability disorders, with the CaMKII-specific peptide inhibitor CN21 reduces transient and persistent currents in Nav1.6-expressing Purkinje neurons by 87%. Using whole-cell voltage clamp of Nav1.6, we show that CaMKII inhibition in ND7/23 and HEK293 cells significantly reduces transient and persistent currents by 72% and produces a 5.8-mV depolarizing shift in the voltage dependence of activation. Immobilized peptide arrays and nanoflow LC-electrospray ionization/MS of Nav1.6 reveal potential sites of CaMKII phosphorylation, specifically Ser-561 and Ser-641/Thr-642 within the first intracellular loop of the channel. Using site-directed mutagenesis to test multiple potential sites of phosphorylation, we show that Ala substitutions of Ser-561 and Ser-641/Thr-642 recapitulate the depolarizing shift in activation and reduction in current density. Computational simulations to model effects of CaMKII inhibition on Nav1.6 function demonstrate dramatic reductions in spontaneous and evoked action potentials in a Purkinje cell model, suggesting that CaMKII modulation of Nav1.6 may be a powerful mechanism to regulate neuronal excitability.
Collapse
Affiliation(s)
- Agnes S Zybura
- Program in Medical Neuroscience, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Anthony J Baucum
- Program in Medical Neuroscience, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Biology Department, Indiana University-Purdue University Indianapolis, School of Science, Indianapolis, Indiana, USA
| | | | - Theodore R Cummins
- Program in Medical Neuroscience, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Biology Department, Indiana University-Purdue University Indianapolis, School of Science, Indianapolis, Indiana, USA
| | - Andy Hudmon
- Program in Medical Neuroscience, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA .,Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, USA
| |
Collapse
|
7
|
Upregulation of Nav1.6 expression in the rostral ventrolateral medulla of stress-induced hypertensive rats. Hypertens Res 2018; 41:1013-1022. [PMID: 30287879 DOI: 10.1038/s41440-018-0105-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 04/06/2018] [Accepted: 04/09/2018] [Indexed: 02/07/2023]
Abstract
The rostral ventrolateral medulla (RVLM) plays a key role in mediating the development of stress-induced hypertension (SIH) by excitation and/or inhibition of sympathetic preganglionic neurons. The voltage-gated sodium channel Nav1.6 has been found to contribute to neuronal hyperexcitability. To examine the expression of Nav1.6 in the RVLM during SIH, a rat model was established by administering electric foot-shocks and noises. We found that Nav1.6 protein expression in the RVLM of SIH rats was higher than that of control rats, peaking at the tenth day of stress. Furthermore, we observed changes in blood pressure correlating with days of stress, with systolic blood pressure (SBP) found to reach a similarly timed peak at the tenth day of stress. Percentages of cells exhibiting colocalization of Nav1.6 with NeuN, a molecular marker of neurons, indicated a strong correlation between upregulation of Nav1.6 expression in NeuN-positive cells and SBP. The level of RSNA was significantly increased after 10 days of stress induction than control group. Compared with the SIHR, knockdown of Nav1.6 in RVLM of the SIHR decreased the level of SBP, heart rate (HR) and renal sympathetic nerve activity (RSNA). These results suggest that upregulated Nav1.6 expression within neurons in the RVLM of SIH rats may contribute to overactivation of the sympathetic system in response to SIH development.
Collapse
|