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Madden KM, Feldman B, Meneilly GS. Baroreflex function and postprandial hypotension in older adults. Clin Auton Res 2020; 31:273-280. [PMID: 32062813 DOI: 10.1007/s10286-020-00671-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 02/07/2020] [Indexed: 10/25/2022]
Abstract
PURPOSE Postprandial hypotension (PPH) is a common but poorly understood etiology for fainting in older adults. One potential mechanism is age-related baroreflex dysfunction. We examined baroreflex function in older adults with PPH and without PPH (noPPH) during a standardized meal test. METHODS 57 adults (age ≥ 65; 24 PPH, 33 noPPH, mean age 77.9 ± 0.9 years, 54% female) were recruited and had meal tests performed. The baroreflex effectiveness index (BEI, %) and baroreflex sensitivity (BRS, ms/mm Hg) were calculated using the sequence method. RESULTS Baseline BEI (22 ± 2 versus 23 ± 2 percent, t = - 0.411, p = 0.682) and BRS (14.1 ± 2.4 versus 13.8 ± 2.5 ms/mm of Hg, t = - 0.084, p = 0.933) were similar in PPH and noPPH subjects. During the meal test PPH subjects showed significantly lower BEI as compared to noPPH subjects (time × PPH, F = 2.791, p = 0.042), while there was no difference in the postprandial change in BRS (time, F = 0.618, p = 0.605). CONCLUSION Patients with PPH demonstrated an acute postprandial decrease in baroreflex effectiveness during meal testing as compared with normal subjects, suggesting a potential contributing mechanism for this condition.
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Affiliation(s)
- Kenneth M Madden
- Gerontology and Diabetes Research Laboratory, Division of Geriatric Medicine, Department of Medicine, University of British Columbia, Vancouver, BC, Canada. .,Centre for Hip Health and Mobility, University of British Columbia, Vancouver, BC, Canada. .,Allan M. McGavin Chair in Geriatric Medicine, Room 7185, Gordon and Leslie Diamond Health Care Centre, 2775 Laurel St., Vancouver, BC, V5Z 1M9, Canada.
| | - Boris Feldman
- Gerontology and Diabetes Research Laboratory, Division of Geriatric Medicine, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Graydon S Meneilly
- Gerontology and Diabetes Research Laboratory, Division of Geriatric Medicine, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
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Greig NH, Tweedie D, Rachmany L, Li Y, Rubovitch V, Schreiber S, Chiang YH, Hoffer BJ, Miller J, Lahiri DK, Sambamurti K, Becker RE, Pick CG. Incretin mimetics as pharmacologic tools to elucidate and as a new drug strategy to treat traumatic brain injury. Alzheimers Dement 2014; 10:S62-75. [PMID: 24529527 PMCID: PMC4201593 DOI: 10.1016/j.jalz.2013.12.011] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 12/05/2013] [Indexed: 01/12/2023]
Abstract
Traumatic brain injury (TBI), either as an isolated injury or in conjunction with other injuries, is an increasingly common event. An estimated 1.7 million injuries occur within the USA each year and 10 million people are affected annually worldwide. Indeed, nearly one third (30.5%) of all injury-related deaths in the USA are associated with TBI, which will soon outpace many common diseases as the major cause of death and disability. Associated with a high morbidity and mortality and no specific therapeutic treatment, TBI has become a pressing public health and medical problem. The highest incidence of TBI occurs in young adults (15-24 years age) and in the elderly (≥75 years of age). Older individuals are particularly vulnerable to these types of injury, often associated with falls, and have shown increased mortality and worse functional outcome after lower initial injury severity. In addition, a new and growing form of TBI, blast injury, associated with the detonation of improvised explosive devices in the war theaters of Iraq and Afghanistan, are inflicting a wave of unique casualties of immediate impact to both military personnel and civilians, for which long-term consequences remain unknown and may potentially be catastrophic. The neuropathology underpinning head injury is becoming increasingly better understood. Depending on severity, TBI induces immediate neuropathologic effects that, for the mildest form, may be transient; however, with increasing severity, these injuries cause cumulative neural damage and degeneration. Even with mild TBI, which represents the majority of cases, a broad spectrum of neurologic deficits, including cognitive impairments, can manifest that may significantly influence quality of life. Further, TBI can act as a conduit to longer term neurodegenerative disorders. Prior studies of glucagon-like peptide-1 (GLP-1) and long-acting GLP-1 receptor agonists have demonstrated neurotrophic/neuroprotective activities across a broad spectrum of cellular and animal models of chronic neurodegenerative (Alzheimer's and Parkinson's diseases) and acute cerebrovascular (stroke) disorders. In view of the mechanisms underpinning these disorders as well as TBI, we review the literature and recent studies assessing GLP-1 receptor agonists as a potential treatment strategy for mild to moderate TBI.
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Affiliation(s)
- Nigel H Greig
- Drug Design & Development Section, Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA.
| | - David Tweedie
- Drug Design & Development Section, Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Lital Rachmany
- Department of Anatomy & Anthropology, Sackler School of Medicine and Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel
| | - Yazhou Li
- Drug Design & Development Section, Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Vardit Rubovitch
- Department of Anatomy & Anthropology, Sackler School of Medicine and Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel
| | - Shaul Schreiber
- Department of Psychiatry, Tel Aviv Sourasky Medical Center and Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Yung-Hsiao Chiang
- Department of Neurosurgery, Taipei Medical University Hospital, Taipei City, Taiwan, ROC; Graduate Institute of Neural Regenerative Medicine, Taipei Medical University, Taipei City, Taiwan, ROC
| | - Barry J Hoffer
- Department of Neurosurgery, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Jonathan Miller
- Department of Neurosurgery, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Debomoy K Lahiri
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Kumar Sambamurti
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - Robert E Becker
- Drug Design & Development Section, Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA; Aristea Translational Medicine, Park City, UT, USA
| | - Chaim G Pick
- Department of Anatomy & Anthropology, Sackler School of Medicine and Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel
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Exendin-4 improves blood glucose control in both young and aging normal non-diabetic mice, possible contribution of beta cell independent effects. PLoS One 2011; 6:e20443. [PMID: 21655268 PMCID: PMC3105063 DOI: 10.1371/journal.pone.0020443] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 05/03/2011] [Indexed: 12/25/2022] Open
Abstract
Aims Type 2 diabetes is highly prevalent in the elderly population. Glucagon like Peptide-1 mimetic such as exendin-4 augments post-prandial insulin secretion. However, the potential influence of aging on the therapeutic effects of this peptide has not been well studied. In this study, we examined the glucose regulatory effects of exendin-4 in mice with different ages. Methods We treated 3-month and 20 to 22-month old C57/DBA mice with 10 nM/kg exendin-4 for 10 days with measurements of blood glucose and body weight. We performed OGTT and ITT to evaluate the glucose response and insulin sensitivity. Islet morphology and beta cell mass were measured by immuno-staining and beta cell proliferation was evaluated by BrdU incorporation and PCNA staining. Real-time PCR and western blot were used to measure protein changes in the liver tissue after exendin-4 treatment. Results Exendin-4 treatment improved glycemic control in both 3-month and 20 to 22-month old mice. In both groups of mice, the blood glucose lowering effect was independent of beta cell function as indicated by unchanged beta cell proliferation, insulin secretion or beta cell mass. Moreover, we found that exendin-4 treatment increased hepatic AKT and FOXO1 phosphorylation and inhibited glucose-6-phosphotase (G6P) and Phosphoenolpyruvate carboxykinase (PEPCK) expression in young mice, but this effect was attenuated in aging mice while the insulin sensitivity showed no change in the young group but significantly improved in aging mice. Conclusion Based on these data, we conclude that the glucose lowering effect of exendin-4 in normal non-diabetic mice was not blunted by aging. We further showed that although there was slight difference in the glucose modulating mechanism of exendin-4 therapy in young and aged mice, the improved glucose control seemed uncorrelated with increased beta cell mass or insulin secretion.
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Chan HM, Jain R, Ahrén B, Pacini G, D'Argenio DZ. Effects of increasing doses of glucagon-like peptide-1 on insulin-releasing phases during intravenous glucose administration in mice. Am J Physiol Regul Integr Comp Physiol 2011; 300:R1126-33. [PMID: 21307364 DOI: 10.1152/ajpregu.00687.2010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The increase in insulin secretion caused by glucagon-like peptide-1 (GLP-1) and GLP-1 mimetics observed during an intravenous glucose test (IVGTT) has been reported in both normal and disease animal models, as well as in humans. In this study, a hierarchical population modeling approach is used, together with a previously reported model relating glucose to insulin appearance, to determine quantitative in vivo dose-response relationships between GLP-1 dose level and both first- and second-phase insulin release. Parameters of the insulin kinetic model were estimated from the complete set of glucose and insulin data collected in 219 anesthetized nonfasted NMR-imaged mice after intravenous injection of glucose (1 g/kg) alone or with GLP-1 (0.03-100 nmol/kg). The resulting dose-response curves indicate a difference in GLP-1 effect on the two release phases, as is also evident from the different ED(50) parameter values (0.107 vs. 6.65 nmol/kg for phase 1 vs. phase 2 insulin release parameters). The first phase of insulin release is gradually augmented with increasing GLP-1 dose, reaching saturation at a dose of ~1 nmol/kg, while the second-phase release changes more abruptly at GLP-1 doses between 3 and 10 nmol/kg and shows a more pronounced 100-fold increase between control and the high GLP-1 dose of 100 nmol/kg Moreover, separate disposition indices calculated for phase 1 and 2 insulin release, show a different pattern of increase with increasing GLP-1 dose.
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Affiliation(s)
- Hui Min Chan
- Dept. of Biomedical Engineering, University of Southern California, 1042 Downey Way, Los Angeles, CA 90089, USA
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Beneficial effects of sub-chronic activation of glucagon-like peptide-1 (GLP-1) receptors on deterioration of glucose homeostasis and insulin secretion in aging mice. Exp Gerontol 2006; 42:296-300. [PMID: 17184947 DOI: 10.1016/j.exger.2006.10.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Revised: 10/18/2006] [Accepted: 10/24/2006] [Indexed: 10/23/2022]
Abstract
Aging is associated with an increased incidence of glucose intolerance and type 2 diabetes. Glucagon-like peptide-1 (GLP-1) is an important insulinotropic peptide secreted from the gastrointestinal tract in response to nutrient absorption. The present study was designed to assess the sub-chronic glucose regulatory effects of the potent long-acting GLP-1 receptor agonist, (Val(8))GLP-1, in aging 45-49 week old mice. Daily injection of (Val(8))GLP-1 (25 n mol/kg body weight) for 12 days had no significant effect on food intake, body weight, non-fasting plasma glucose and insulin concentrations. However, after 12 days, the glycaemic response to intraperitoneal glucose was improved (P<0.05) in (Val(8))GLP-1 treated mice. In keeping with this, glucose-mediated insulin secretion was enhanced (P<0.05) and insulin sensitivity improved (P<0.05) compared to controls. These data indicate that sub-chronic activation of the GLP-1 receptor by daily treatment with (Val(8))GLP-1 counters aspects of the age-related impairment of pancreatic beta-cell function and insulin sensitivity.
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Abstract
Despite dramatically increased research efforts to discover cures for the rising health issue of obesity, bariatric (obesity) surgery remains the most effective treatment. Obese people and especially those classified as morbidly obese often suffer from associated co-morbid conditions such as type-II diabetes. In most cases, bariatric surgery results in rapid and sustained decreases in excess body weight. Recent reports have identified significant improvements in glucose homeostasis after surgery that are coincident and often precedent to any measurable weight loss. These studies suggest an inhibition or enhancement of a "factor" within the intestinal tract that improves glycemia independent of body fat stores. These observations have sparked renewed investigation into the mechanisms underlying successful obesity surgeries such as gastric bypass. It is becoming increasingly clear that restriction and malabsorption are not the only two mechanisms important for inducing long-term weight loss or the improvements in diabetes. Investigating the hypothesis that the distal intestine (ileum) holds additional answers into a third mechanism, I used the model of ileal transposition to help identify endocrine changes in the gut following obesity surgery. This review will explore the model of ileal transposition and speculate on its usefulness as a tool to dissect out additional mechanisms underlying effective obesity surgeries. Also discussed will be the ileal-produced hormone glucagon-like peptide and its role in mediating the improvements in diabetes and weight loss after bariatric surgery.
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Affiliation(s)
- April D Strader
- Southern Illinois University School of Medicine, Department of Physiology, Life Science III - Room 2066, 1135 Lincoln Drive, Carbondale, IL 62901, USA.
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