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Balasubramanian P, Branen L, Sivasubramanian MK, Monteiro R, Subramanian M. Aging is associated with glial senescence in the brainstem - implications for age-related sympathetic overactivity. Aging (Albany NY) 2021; 13:13460-13473. [PMID: 34038388 PMCID: PMC8202881 DOI: 10.18632/aging.203111] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 04/28/2021] [Indexed: 12/11/2022]
Abstract
Accumulating evidence suggests that the sympathetic nervous system (SNS) overactivity plays a crucial role in age-related increase in the risk for cardiovascular diseases such as hypertension, myocardial infarction, stroke and heart diseases. Previous studies indicate that neuroinflammation in key brainstem regions that regulate sympathetic outflow plays a pathogenic role in aging-mediated sympathoexcitation. However, the molecular mechanisms underlying this phenomenon are not clear. While senescent cells and their secretory phenotype (SASP) have been implicated in the pathogenesis of several age-related diseases, their role in age-related neuroinflammation in the brainstem and SNS overactivity has not been investigated. To test this, we isolated brainstems from young (2-4 months) and aged (24 months) male C57BL/6J mice and assessed senescence using a combination of RNA-in situ hybridization, PCR analysis, multiplex assay and SA-β gal staining. Our results show significant increases in p16Ink4a expression, increased activity of SA-β gal and increases in SASP levels in the aged brainstem, suggesting age-induced senescence in the brainstem. Further, analysis of senescence markers in glial cells enriched fraction from fresh brainstem samples demonstrated that glial cells are more susceptible to senesce with age in the brainstem. In conclusion, our study suggests that aging induces glial senescence in the brainstem which likely causes inflammation and SNS overactivity.
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Affiliation(s)
- Priya Balasubramanian
- Oklahoma Center for Geroscience and Healthy Brain Aging, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Lyndee Branen
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA
| | - Mahesh Kumar Sivasubramanian
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA
| | - Raisa Monteiro
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA
| | - Madhan Subramanian
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA
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Subramanian M, Edwards L, Melton A, Branen L, Herron A, Sivasubramanian MK, Monteiro R, Stansbury S, Balasubramanian P, Morris L, Elkholey K, Niewiadomska M, Stavrakis S. Non-invasive vagus nerve stimulation attenuates proinflammatory cytokines and augments antioxidant levels in the brainstem and forebrain regions of Dahl salt sensitive rats. Sci Rep 2020; 10:17576. [PMID: 33067477 PMCID: PMC7567801 DOI: 10.1038/s41598-020-74257-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 08/21/2020] [Indexed: 12/16/2022] Open
Abstract
The anti-inflammatory effects of vagus nerve stimulation are well known. It has recently been shown that low-level, transcutaneous stimulation of vagus nerve at the tragus (LLTS) reduces cardiac inflammation in a rat model of heart failure with preserved ejection fraction (HFpEF). The mechanisms by which LLTS affect the central neural circuits within the brain regions that are important for the regulation of cardiac vagal tone are not clear. Female Dahl salt-sensitive rats were initially fed with either low salt (LS) or high salt (HS) diet for a period of 6 weeks, followed by sham or active stimulation (LLTS) for 30 min daily for 4 weeks. To study the central effects of LLTS, four brainstem (SP5, NAb, NTS, and RVLM) and two forebrain sites (PVN and SFO) were examined. HS diet significantly increased the gene expression of proinflammatory cytokines in the SP5 and SFO. LLTS reversed HS diet-induced changes at both these sites. Furthermore, LLTS augmented the levels of antioxidant Nrf2 in the SP5 and SFO. Taken together, these findings suggest that LLTS has central anti-inflammatory and antioxidant properties that could mediate the neuromodulation of cardiac vagal tone in the rat model of HFpEF.
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Affiliation(s)
- Madhan Subramanian
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, 277 McElroy Hall, Stillwater, OK, 74078, USA.
| | - Laura Edwards
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, 277 McElroy Hall, Stillwater, OK, 74078, USA
| | - Avery Melton
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, 277 McElroy Hall, Stillwater, OK, 74078, USA
| | - Lyndee Branen
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, 277 McElroy Hall, Stillwater, OK, 74078, USA
| | - Angela Herron
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, 277 McElroy Hall, Stillwater, OK, 74078, USA
| | - Mahesh Kumar Sivasubramanian
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, 277 McElroy Hall, Stillwater, OK, 74078, USA
| | - Raisa Monteiro
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, 277 McElroy Hall, Stillwater, OK, 74078, USA
| | - Samantha Stansbury
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, 277 McElroy Hall, Stillwater, OK, 74078, USA
| | - Priya Balasubramanian
- Reynolds Oklahoma Center On Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Lynsie Morris
- Department of Medicine, Cardiovascular Section, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Department of Medicine, Heart Rhythm Institute, University of Oklahoma Health Sciences Center, 800 Stanton L Young Blvd, Suite 5400, Oklahoma City, OK, 73104, USA
| | - Khaled Elkholey
- Department of Medicine, Cardiovascular Section, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Monika Niewiadomska
- Department of Medicine, Cardiovascular Section, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Stavros Stavrakis
- Department of Medicine, Cardiovascular Section, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
- Department of Medicine, Heart Rhythm Institute, University of Oklahoma Health Sciences Center, 800 Stanton L Young Blvd, Suite 5400, Oklahoma City, OK, 73104, USA.
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