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Martinez-Feduchi P, Jin P, Yao B. Epigenetic modifications of DNA and RNA in Alzheimer's disease. Front Mol Neurosci 2024; 17:1398026. [PMID: 38726308 PMCID: PMC11079283 DOI: 10.3389/fnmol.2024.1398026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 04/15/2024] [Indexed: 05/12/2024] Open
Abstract
Alzheimer's disease (AD) is a complex neurodegenerative disorder and the most common form of dementia. There are two main types of AD: familial and sporadic. Familial AD is linked to mutations in amyloid precursor protein (APP), presenilin-1 (PSEN1), and presenilin-2 (PSEN2). On the other hand, sporadic AD is the more common form of the disease and has genetic, epigenetic, and environmental components that influence disease onset and progression. Investigating the epigenetic mechanisms associated with AD is essential for increasing understanding of pathology and identifying biomarkers for diagnosis and treatment. Chemical covalent modifications on DNA and RNA can epigenetically regulate gene expression at transcriptional and post-transcriptional levels and play protective or pathological roles in AD and other neurodegenerative diseases.
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Affiliation(s)
| | | | - Bing Yao
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, United States
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2
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Actions and Consequences of Insulin in the Striatum. Biomolecules 2023; 13:biom13030518. [PMID: 36979453 PMCID: PMC10046598 DOI: 10.3390/biom13030518] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 02/26/2023] [Accepted: 02/27/2023] [Indexed: 03/14/2023] Open
Abstract
Insulin crosses the blood–brain barrier to enter the brain from the periphery. In the brain, insulin has well-established actions in the hypothalamus, as well as at the level of mesolimbic dopamine neurons in the midbrain. Notably, insulin also acts in the striatum, which shows abundant expression of insulin receptors (InsRs) throughout. These receptors are found on interneurons and striatal projections neurons, as well as on glial cells and dopamine axons. A striking functional consequence of insulin elevation in the striatum is promoting an increase in stimulated dopamine release. This boosting of dopamine release involves InsRs on cholinergic interneurons, and requires activation of nicotinic acetylcholine receptors on dopamine axons. Opposing this dopamine-enhancing effect, insulin also increases dopamine uptake through the action of insulin at InsRs on dopamine axons. Insulin acts on other striatal cells as well, including striatal projection neurons and astrocytes that also influence dopaminergic transmission and striatal function. Linking these cellular findings to behavior, striatal insulin signaling is required for the development of flavor–nutrient learning, implicating insulin as a reward signal in the brain. In this review, we discuss these and other actions of insulin in the striatum, including how they are influenced by diet and other physio-logical states.
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Al-Onaizi M, Al-Sarraf A, Braysh K, Kazem F, Al-Hussaini H, Rao M, Kilarkaje N, ElAli A. Impaired spatial navigation and age-dependent hippocampal synaptic dysfunction are associated with chronic inflammatory response in db/db mice. Eur J Neurosci 2022; 56:6003-6021. [PMID: 36226387 DOI: 10.1111/ejn.15835] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 08/18/2022] [Accepted: 09/23/2022] [Indexed: 12/29/2022]
Abstract
Type 2 diabetes mellitus (T2DM) increases the risk of developing Alzheimer's disease (AD), which has been proposed to be driven by an abnormal neuroinflammatory response affecting cognitive function. However, the impact of T2DM on hippocampal function and synaptic integrity during aging has not been investigated. Here, we investigated the effects of aging in T2DM on AD-like pathology using the leptin receptor-deficient db/db mouse model of T2DM. Our results indicate that adult T2DM mice exhibited impaired spatial acquisition in the Morris water maze (MWM). Morphological analysis showed an age-dependent neuronal loss in the dentate gyrus. We found that astrocyte density was significantly decreased in all regions of the hippocampus in T2DM mice. Our analysis showed that microglial activation was increased in the CA3 and the dentate gyrus of the hippocampus in an age-dependent manner in T2DM mice. However, the expression of presynaptic marker protein (synaptophysin) and the postsynaptic marker protein [postsynaptic density protein 95 (PSD95)] was unchanged in the hippocampus of adult T2DM mice. Interestingly, synaptophysin and PSD95 expression significantly decreased in the hippocampus of aged T2DM mice, suggesting an impaired hippocampal synaptic integrity. Cytokine profiling analysis displayed a robust pro-inflammatory cytokine profile in the hippocampus of aged T2DM mice compared with the younger cohort, outlining the role of aging in exacerbating the neuroinflammatory profile in the diabetic state. Our results suggest that T2DM impairs cognitive function by promoting neuronal loss in the dentate gyrus and triggering an age-dependent deterioration in hippocampal synaptic integrity, associated with an aberrant neuroinflammatory response.
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Affiliation(s)
- Mohammed Al-Onaizi
- Department of Anatomy, Faculty of Medicine, Kuwait University, Kuwait City, Kuwait
| | - Ahmad Al-Sarraf
- Undergraduate Medical Degree Program, Faculty of Medicine, Kuwait University, Kuwait City, Kuwait
| | - Kawthar Braysh
- Department of Anatomy, Faculty of Medicine, Kuwait University, Kuwait City, Kuwait
| | - Fatema Kazem
- Undergraduate Medical Degree Program, Faculty of Medicine, Kuwait University, Kuwait City, Kuwait
| | - Heba Al-Hussaini
- Department of Anatomy, Faculty of Medicine, Kuwait University, Kuwait City, Kuwait
| | - Muddanna Rao
- Department of Anatomy, Faculty of Medicine, Kuwait University, Kuwait City, Kuwait
| | - Narayana Kilarkaje
- Department of Anatomy, Faculty of Medicine, Kuwait University, Kuwait City, Kuwait
| | - Ayman ElAli
- Neuroscience Axis, Research Center of CHU de Québec, Université Laval, Quebec City, Quebec, Canada.,Department of Psychiatry and Neuroscience, Faculty of Medicine, Université Laval, Quebec City, Quebec, Canada
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4
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Dubey SK, Lakshmi KK, Krishna KV, Agrawal M, Singhvi G, Saha RN, Saraf S, Saraf S, Shukla R, Alexander A. Insulin mediated novel therapies for the treatment of Alzheimer's disease. Life Sci 2020; 249:117540. [PMID: 32165212 DOI: 10.1016/j.lfs.2020.117540] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 03/03/2020] [Accepted: 03/07/2020] [Indexed: 12/16/2022]
Abstract
Alzheimer's disease, a progressive neurodegenerative disorder, is one of the leading causes of death in the USA, along with cancer and cardiac disorders. AD is characterized by various neurological factors like amyloid plaques, tau hyperphosphorylation, mitochondrial dysfunction, acetylcholine deficiency, etc. Together, impaired insulin signaling in the brain is also observed as essential factor to be considered in AD pathophysiology. Hence, currently researchers focused on studying the effect of brain insulin metabolism and relation of diabetes with AD. Based on the investigations, AD is also considered as type 3 or brain diabetes. Besides the traditional view of correlating AD with aging, a better understanding of various pathological factors and effects of other physical ailments is necessary to develop a promising therapeutic approach. There is a vast scope of studying the relation of systemic insulin level, insulin signaling, its neuroprotective potency and effect of diabetes on AD progression. The present work describes worldwide status of AD and its relation with diabetes mellitus and insulin metabolism; pathophysiology of AD; different metabolic pathways associating insulin metabolism with AD; insulin receptor and signaling in the brain; glucose metabolism; insulin resistance; and various preclinical and clinical studies reported insulin-based therapies to treat AD via systemic route and through direct intranasal delivery to the brain.
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Affiliation(s)
- Sunil Kumar Dubey
- Department of Pharmacy, Birla Institute of Technology and Science, Pilani (BITS-PILANI), Pilani Campus, Rajasthan, India.
| | - K K Lakshmi
- Department of Pharmacy, Birla Institute of Technology and Science, Pilani (BITS-PILANI), Pilani Campus, Rajasthan, India
| | - Kowthavarapu Venkata Krishna
- Department of Pharmacy, Birla Institute of Technology and Science, Pilani (BITS-PILANI), Pilani Campus, Rajasthan, India
| | - Mukta Agrawal
- Rungta College of Pharmaceutical Sciences and Research, Kohka-Kurud Road, Bhilai, Chhattisgarh 490 024, India
| | - Gautam Singhvi
- Department of Pharmacy, Birla Institute of Technology and Science, Pilani (BITS-PILANI), Pilani Campus, Rajasthan, India
| | - Ranendra Narayana Saha
- Department of Biotechnology, Birla Institute of Technology and Science, Pilani (BITS-PILANI), Dubai Campus, Dubai, United Arab Emirates
| | - Swarnlata Saraf
- University Institute of Pharmacy, Pt. Ravishankar Shukla University, Raipur, Chhattisgarh 492010, India
| | - Shailendra Saraf
- University Institute of Pharmacy, Pt. Ravishankar Shukla University, Raipur, Chhattisgarh 492010, India
| | - Rahul Shukla
- Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research (NIPER-R), New Transit Campus, Bijnor Road, Sarojini Nagar, Lucknow 226002, India
| | - Amit Alexander
- National Institute of Pharmaceutical Education and Research (NIPER-Guwahati), Department of Pharmaceuticals, Ministry of Chemicals & Fertilizers, Govt. of India, NH 37, NITS Mirza, Kamrup-781125, Guwahati, Assam, India.
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5
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Sadeghi A, Asghari H, Hami J, Mohasel Roodi M, Mostafaee H, Karimipour M, Namavar M, Idoon F. Volumetric investigation of the hippocampus in rat offspring due to diabetes in pregnancy–A stereological study. J Chem Neuroanat 2019; 101:101669. [DOI: 10.1016/j.jchemneu.2019.101669] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 06/23/2019] [Accepted: 08/19/2019] [Indexed: 02/05/2023]
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Spinelli M, Fusco S, Grassi C. Brain Insulin Resistance and Hippocampal Plasticity: Mechanisms and Biomarkers of Cognitive Decline. Front Neurosci 2019; 13:788. [PMID: 31417349 PMCID: PMC6685093 DOI: 10.3389/fnins.2019.00788] [Citation(s) in RCA: 144] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/15/2019] [Indexed: 12/27/2022] Open
Abstract
In the last decade, much attention has been devoted to the effects of nutrient-related signals on brain development and cognitive functions. A turning point was the discovery that brain areas other than the hypothalamus expressed receptors for hormones related to metabolism. In particular, insulin signaling has been demonstrated to impact on molecular cascades underlying hippocampal plasticity, learning and memory. Here, we summarize the molecular evidence linking alteration of hippocampal insulin sensitivity with changes of both adult neurogenesis and synaptic plasticity. We also review the epidemiological studies and experimental models emphasizing the critical role of brain insulin resistance at the crossroad between metabolic and neurodegenerative disease. Finally, we brief novel findings suggesting how biomarkers of brain insulin resistance, involving the study of brain-derived extracellular vesicles and brain glucose metabolism, may predict the onset and/or the progression of cognitive decline.
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Affiliation(s)
- Matteo Spinelli
- Institute of Human Physiology, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Salvatore Fusco
- Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy
| | - Claudio Grassi
- Institute of Human Physiology, Università Cattolica del Sacro Cuore, Rome, Italy.,Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy
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7
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Sadeghi A, Esfandiary E, Hami J, Khanahmad H, Hejazi Z, Mardani M, Razavi S. The effects of maternal diabetes and insulin treatment on neurogenesis in the developing hippocampus of male rats. J Chem Neuroanat 2018; 91:27-34. [DOI: 10.1016/j.jchemneu.2018.03.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/17/2018] [Accepted: 03/21/2018] [Indexed: 12/19/2022]
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Rodriguez-Raecke R, Brünner YF, Kofoet A, Mutic S, Benedict C, Freiherr J. Odor Sensitivity After Intranasal Insulin Application Is Modulated by Gender. Front Endocrinol (Lausanne) 2018; 9:580. [PMID: 30356884 PMCID: PMC6190874 DOI: 10.3389/fendo.2018.00580] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 09/12/2018] [Indexed: 11/13/2022] Open
Abstract
Obesity constitutes a global health care problem, and often eating habits are to blame. For intervention, a thorough understanding of energy intake and expenditure is needed. In recent years, the pivotal role of insulin in connection to energy intake was established. Olfactory sensitivity may be a target of cerebral insulin action to maintain body weight. With this experiment, we aimed to explore the influence of intranasal insulin on olfactory sensitivity for the odors n-butanol and peanut in a placebo-controlled, double-blind setting in a within-subject design. All subjects participated in two experimental sessions on separate days and received either intranasal insulin or placebo in a pseudorandomized order. Application was followed by two olfactory threshold tests for n-butanol and peanut in a pseudorandomized order. After a single dose of intranasal insulin (40 IU) or placebo (0.4 ml), olfactory sensitivity for the odorants n-butanol and peanut were examined in 30 healthy normosmic participants (14 females). Measured blood parameters revealed no decrease in plasma glucose, however, insulin, leptin and cortisol levels were affected following intranasal application. Females' but not males' olfactory sensitivity for n-butanol was lower after intranasal insulin administration vs. placebo. In contrast, olfactory sensitivity for peanut was not influenced by intranasal insulin application. Our results indicate that the effects of cortical insulin levels on processing of specific odors is likely modulated by gender, as central increase of insulin concentration led to a reduced olfactory sensitivity for n-butanol in women only, which might be due to differentially regulated insulin and leptin signaling in men and women.
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Affiliation(s)
- Rea Rodriguez-Raecke
- Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany
- Sensory Analytics, Fraunhofer Institute for Process Engineering and Packaging IVV, Freising, Germany
- *Correspondence: Rea Rodriguez-Raecke
| | - Yvonne F. Brünner
- Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany
| | - Anja Kofoet
- Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany
| | - Smiljana Mutic
- Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany
| | | | - Jessica Freiherr
- Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany
- Sensory Analytics, Fraunhofer Institute for Process Engineering and Packaging IVV, Freising, Germany
- Jessica Freiherr
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Small DM. Dopamine Adaptations as a Common Pathway for Neurocognitive Impairment in Diabetes and Obesity: A Neuropsychological Perspective. Front Neurosci 2017; 11:134. [PMID: 28400713 PMCID: PMC5368264 DOI: 10.3389/fnins.2017.00134] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 03/06/2017] [Indexed: 01/06/2023] Open
Abstract
Evidence accumulates linking obesity and diabetes with cognitive dysfunction. At present the mechanism(s) underlying these associations and the relative contribution of diet, adiposity, and metabolic dysfunction are unknown. In this perspective key gaps in knowledge are outlined and an initial sketch of a neuropsychological profile is developed that points toward a critical role for dopamine (DA) adaptations in neurocognitive impairment secondary to diabetes and obesity. The precise mechanisms by which diet, metabolic dysfunction, and adiposity influence the DA system to impact cognition remains unclear and is an important direction for future research.
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Affiliation(s)
- Dana M Small
- The John B Pierce LaboratoryNew Haven, CT, USA; Department of Psychiatry, Yale University School of MedicineNew Haven, CT, USA
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10
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Sadeghi A, Esfandiary E, Hami J, Khanahmad H, Hejazi Z, Razavi S. Effect of maternal diabetes on gliogensis in neonatal rat hippocampus. Adv Biomed Res 2016; 5:142. [PMID: 27656611 PMCID: PMC5025925 DOI: 10.4103/2277-9175.187376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 11/14/2015] [Indexed: 11/29/2022] Open
Abstract
Background: Diabetes in pregnancy is a common metabolic disorder associated with various adverse outcomes in the offspring including impairments in attention and memory and alterations in social behavior. Glial cells are proven to have a critical role in normal function of neurons, and alteration in their activity could contribute to disturbance in the brain function. The aim of this study was to investigate the effect of maternal diabetes on hippocampal mRNA expression and distribution pattern of glial fibrillary acidic protein (GFAP) immunoreactive glial cells in the dentate gyrus (DG) of rat neonate at postnatal day 14 (P14). Materials and Methods: Wistar female rats were randomly allocated in control, diabetic, and insulin-treated diabetic groups. Diabetes was induced by injection of streptozotocin from 4 weeks before gestation until parturition. After delivery, the male offspring was euthanized at P14. Results: Our results showed a significant higher level of hippocampal GFAP expression and an increase in the mean number of GFAP positive cells in the DG of diabetic group offspring (P < 0.05). We also found an insignificant up-regulation in the expression of GFAP and the mean number of positive cells in the insulin-treated diabetic group neonates as compared to control group (P > 0.05). Conclusion: The present study revealed that diabetes during pregnancy strongly increased the glial cells production in the developing rat hippocampus.
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Affiliation(s)
- Akram Sadeghi
- Department of Anatomical Sciences, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Ebrahim Esfandiary
- Department of Anatomical Sciences, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Javad Hami
- Department of Anatomical Sciences, School of Medicine, Birjand University of Medical Sciences, Birjand, Khorasan, Iran
| | - Hossein Khanahmad
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Zahra Hejazi
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Shahnaz Razavi
- Department of Anatomical Sciences, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
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Mc Allister E, Pacheco-Lopez G, Woods SC, Langhans W. Inconsistencies in the hypophagic action of intracerebroventricular insulin in mice. Physiol Behav 2015; 151:623-8. [PMID: 26344647 DOI: 10.1016/j.physbeh.2015.08.038] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Revised: 08/28/2015] [Accepted: 08/29/2015] [Indexed: 12/16/2022]
Abstract
Insulin inhibits eating after its intracerebroventricular (ICV) administration in multiple species and under a variety of conditions. Nevertheless, the results across reports are inconsistent in that ICV insulin does not always reduce food intake. The reasons for this variability are largely unknown. Using mice as a model, we performed several crossover trials with insulin vs. vehicle when infused into the third cerebral ventricle (i3vt) to test the hypothesis that recent experience with the i3vt procedure contributes to the variability in the effect of ICV insulin on food intake. Using a cross-over design with two days between injections, we found that insulin (0.4 μU/mouse) significantly reduced food intake relative to vehicle in mice that received vehicle on the first and insulin on the second trial, whereas this effect was absent in mice that received insulin on the first and vehicle on the second trial. Higher doses (i3vt 4.0 and 40.0 μU/mouse) had no effect on food intake in this paradigm. When injections were spaced 7 days apart, insulin reduced food intake with no crossover effect. Mice that did not reduce food intake in response to higher doses of i3vt insulin did so in response to i3vt infusion of the melanocortin receptor agonist melanotan-II (MT-II), indicating that the function of the hypothalamic melanocortin system, which mediates the effect of insulin on eating, was not impaired by whatever interfered with the insulin effect, and that this interference occurred upstream of the melanocortin receptors. Overall, our findings suggest that associative effects based on previous experience with the experimental situation can compromise the eating inhibition elicited by i3vt administered insulin.
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Affiliation(s)
- Eugenia Mc Allister
- Physiology and Behavior Laboratory, Swiss Federal Institute of Technology (ETH) Zurich, Schwerzenbach, Switzerland
| | - Gustavo Pacheco-Lopez
- Physiology and Behavior Laboratory, Swiss Federal Institute of Technology (ETH) Zurich, Schwerzenbach, Switzerland; Health Sciences Department, Metropolitan University (UAM) at Lerma, Mexico; Health, Medical and Neuropsychology Unit, Faculty of Social and Behavioural Sciences, University of Leiden, The Netherlands
| | | | - Wolfgang Langhans
- Physiology and Behavior Laboratory, Swiss Federal Institute of Technology (ETH) Zurich, Schwerzenbach, Switzerland.
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Jor’dan AJ, Manor B, Novak V. Slow gait speed - an indicator of lower cerebral vasoreactivity in type 2 diabetes mellitus. Front Aging Neurosci 2014; 6:135. [PMID: 25018729 PMCID: PMC4071640 DOI: 10.3389/fnagi.2014.00135] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 06/09/2014] [Indexed: 01/30/2023] Open
Abstract
OBJECTIVE Gait speed is an important predictor of health that is negatively affected by aging and type 2 diabetes. Diabetes has been linked to reduced vasoreactivity, i.e., the capacity to regulate cerebral blood flow in response to CO2 challenges. This study aimed to determine the relationship between cerebral vasoreactivity and gait speed in older adults with and without diabetes. RESEARCH DESIGN AND METHODS We studied 61 adults with diabetes (65 ± 8 years) and 67 without diabetes (67 ± 9 years) but with similar distribution of cardiovascular risk factors. Preferred gait speed was calculated from a 75 m walk. Global and regional perfusion, vasoreactivity and vasodilation reserve were measured using 3-D continuous arterial spin labeling MRI at 3 Tesla during normo-, hyper- and hypocapnia and normalized for end-tidal CO2. RESULTS Diabetic participants had slower gait speed as compared to non-diabetic participants (1.05 ± 0.15 m/s vs. 1.14 ± 0.14 m/s, p < 0.001). Lower global vasoreactivity (r (2) adj = 0.13, p = 0.007), or lower global vasodilation reserve (r (2) adj = 0.33, p < 0.001), was associated with slower walking in the diabetic group independently of age, BMI and hematocrit concentration. For every 1 mL/100 g/min/mmHg less vasodilation reserve, for example, gait speed was 0.05 m/s slower. Similar relationships between vasodilation reserve and gait speed were also observed regionally within the cerebellum, frontal, temporal, parietal, and occipital lobes (r (2) adj = 0.27-0.33, p < 0.0001). In contrast, vasoreactivity outcomes were not associated with walking speed in non-diabetic participants, despite similar vasoreactivity ranges across groups. CONCLUSION In the diabetic group only, lower global vasoreactivity was associated with slower walking speed. Slower walking in older diabetic adults may thus hallmark reduced vasomotor reserve and thus the inability to increase perfusion in response to greater metabolic demands during walking.
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Affiliation(s)
- Azizah J. Jor’dan
- Syncope and Falls in the Elderly Laboratory, Division of Gerontology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical SchoolBoston, MA, USA
| | - Brad Manor
- Syncope and Falls in the Elderly Laboratory, Division of Gerontology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical SchoolBoston, MA, USA
- Institute for Aging Research, Hebrew SeniorLife, Harvard Medical SchoolBoston, MA, USA
| | - Vera Novak
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical SchoolBoston, MA, USA
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Hami J, Kheradmand H, Haghir H. Sex differences and laterality of insulin receptor distribution in developing rat hippocampus: an immunohistochemical study. J Mol Neurosci 2014; 54:100-8. [PMID: 24573599 DOI: 10.1007/s12031-014-0255-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2013] [Accepted: 02/04/2014] [Indexed: 12/19/2022]
Abstract
This study aimed to compare the regional distribution of insulin receptor in various portions of newborn rat hippocampus on postnatal days 0 (P0), 7 (P7), and 14 (P14) between male/female and right/left hippocampi. We found that the number of insulin receptor (InsR)-immunoreactive-positive (InsR+) cells in CA1 continued to increase until P7 and remained unchanged thereafter. A marked increase in distribution of InsR+ cells in CA3 from P0 to P14 was observed, although there was a significant decline in the number of InsR+ cells in dentate gyrus (DG) at the same time. No differences between the right/left and male/female hippocampi were detected at P0 (P > 0.05). Seven-day-old female rats showed a higher number of labeled cells in the left than in the right hippocampus. Moreover, the differences between the number of InsR+ cells in area CA1 and CA3 were statistically significant between males and females (P < 0.05). At P14, the number of InsR+ cells was significantly higher in CA1 and DG of males, especially in the right one (P < 0.05). These results indicate the existence of a differential distribution pattern of InsR between the left/right and male/female hippocampi. Together with other mechanisms, these differences may underlie sexual dimorphism and left/right asymmetry in the hippocampus.
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Affiliation(s)
- Javad Hami
- Department of Anatomical Sciences, School of Medicine, Birjand University of Medical Sciences, Birjand, Iran
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Abstract
Many peptides and other compounds that influence metabolism also influence food intake, and numerous hypotheses explaining the observed effects in terms of energy homeostasis have been suggested over the years. For example, cholecystokinin (CCK), a duodenal peptide secreted during meals that aids in digestion, also reduces ongoing food intake, thereby contributing to satiation; and insulin and leptin, hormones secreted in direct proportion to body fat, act in the brain to help control adiposity by reducing energy intake. These behavioral actions are often considered to be hard-wired, such that negative experiments, in which an administered compound fails to have its purported effect, are generally disregarded. In point of fact, failures to replicate the effects of compounds on food intake are commonplace, and this occurs both between and within laboratories. Failures to replicate have historically fueled heated debate about the efficacy and/or normal function of one or another compound, leading to confusion and ambiguity in the literature. We review these phenomena and their implications and argue that, rather than eliciting hard-wired behavioral responses in the maintenance of homeostasis, compounds that alter food intake are subjected to numerous influences that can render them completely ineffective at times and that a major reason for this variance is that food intake is not under stringent homeostatic control.
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Affiliation(s)
- Stephen C Woods
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH 45237, USA.
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15
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de la Monte SM. Contributions of brain insulin resistance and deficiency in amyloid-related neurodegeneration in Alzheimer's disease. Drugs 2012; 72:49-66. [PMID: 22191795 PMCID: PMC4550303 DOI: 10.2165/11597760-000000000-00000] [Citation(s) in RCA: 173] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia in North America. Growing evidence supports the concept that AD is fundamentally a metabolic disease that results in progressive impairment in the brain's capacity to utilize glucose and respond to insulin and insulin-like growth factor (IGF) stimulation. Moreover, the heterogeneous nature of AD is only partly explained by the brain's propensity to accumulate aberrantly processed, misfolded and aggregated oligomeric structural proteins, including amyloid-β peptides and hyperphosphorylated tau. Evidence suggests that other factors, including impaired energy metabolism, oxidative stress, neuroinflammation, insulin and IGF resistance, and insulin/IGF deficiency in the brain should be incorporated into an overarching hypothesis to develop more realistic diagnostic and therapeutic approaches to AD. In this review, the interrelationship between impaired insulin and IGF signalling and amyloid-β pathology is discussed along with potential therapeutic approaches. Impairments in brain insulin/IGF signalling lead to increased expression of amyloid-β precursor protein (AβPP) and accumulation of AβPP-Aβ. In addition, they promote oxidative stress and deficits in energy metabolism, leading to the activation of pro-AβPP-Aβ-mediated neurodegeneration cascades. Although brain insulin/IGF resistance and deficiency can be induced by primary or secondary disease processes, the soaring rates of peripheral insulin resistance associated with obesity, diabetes mellitus and metabolic syndrome quite likely play major roles in the current AD epidemic. Both clinical and experimental data have linked chronic hyperinsulinaemia to cognitive impairment and neurodegeneration with increased AβPP-Aβ accumulation/reduced clearance in the CNS. Correspondingly, both the restoration of insulin responsiveness and the use of insulin therapy can lead to improved cognitive performance, although with variable effects on brain AβPP-Aβ load. On the other hand, experimental evidence supports the concept that the toxic effects of AβPP-Aβ can promote insulin resistance. Together, these findings suggest that a positive feedback loop of progressive neurodegeneration can develop whereby insulin resistance drives AβPP-Aβ accumulation, and AβPP-Aβ fibril toxicity drives brain insulin resistance. This phenomenon could explain why measuring AβPP-Aβ levels in cerebrospinal fluid or imaging of the brain has proven to be inadequate as a stand-alone biomarker for diagnosing AD, and why the clinical trial results of anti-AβPP-Aβ monotherapy have been disappointing. Instead, the aggregate data suggest that brain insulin resistance and deficiency must also be therapeutically targeted to halt AD progression or reverse its natural course. The positive therapeutic effects of different treatments that address the role of brain insulin/IGF resistance and deficiency, including the use of intranasal insulin delivery, incretins and insulin sensitizer agents are discussed along with potential benefits of lifestyle changes to modify risk for developing mild cognitive impairment or AD. Altogether, the data strongly support the notion that we must shift toward the implementation of multimodal rather than unimodal diagnostic and therapeutic strategies for AD.
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Affiliation(s)
- Suzanne M de la Monte
- Department of Pathology, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI 02903, USA.
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Arnold JJ, Fyrberg MD, Meezan E, Pillion DJ. Reestablishment of the nasal permeability barrier to several peptides following exposure to the absorption enhancer tetradecyl-beta-D-maltoside. J Pharm Sci 2010; 99:1912-20. [PMID: 19894270 DOI: 10.1002/jps.21977] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Regular insulin, NPH insulin, glargine insulin, calcitonin, and human growth hormone were administered to rats nasally with 0.125% tetradecyl-beta-D-maltoside (TDM), or at various times after TDM treatment. Absorption of all five peptides was enhanced initially and diminished in a time-dependent manner as the interval between administration of TDM and the peptide increased. Changes in nasal morphology were also assessed via transmission electron microscopy (TEM) immediately after TDM treatment and at various times thereafter. TEM analysis demonstrated that 0.125% TDM caused a rapid and transient alteration in the morphology of the apical membrane surface. Fewer cilia were observed and cell-cell junctions were difficult to visualize, but no epithelial cell erosion was apparent. Two hours after TDM treatment, the apical membrane surface once again contained abundant cilia and cell-cell junctions were readily visualized. The complete recovery of the nasal permeability barrier to several different peptides following TDM administration and the concomitant histological evidence demonstrate that TDM treatment transiently perturbs the nasal mucosa to stimulate peptide drug absorption and does not produce irreversible damage to the cells that line the nasal cavity.
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Affiliation(s)
- John J Arnold
- Samford University McWhorter School of Pharmacy, 800 Lakeshore Drive, Birmingham, Alabama 35229, USA.
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Sun MK, Nelson TJ, Alkon DL. PKC and Insulin Pathways in Memory Storage: Targets for Synaptogenesis, Anti-apoptosis, and the Treatment of AD. DIABETES, INSULIN AND ALZHEIMER'S DISEASE 2010. [DOI: 10.1007/978-3-642-04300-0_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Hennige AM, Sartorius T, Lutz SZ, Tschritter O, Preissl H, Hopp S, Fritsche A, Rammensee HG, Ruth P, Häring HU. Insulin-mediated cortical activity in the slow frequency range is diminished in obese mice and promotes physical inactivity. Diabetologia 2009; 52:2416-2424. [PMID: 19756482 DOI: 10.1007/s00125-009-1522-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Accepted: 07/24/2009] [Indexed: 10/20/2022]
Abstract
AIMS/HYPOTHESIS There is evidence from mouse models and humans that alterations in insulin action in the brain are accompanied by an obese phenotype; however, the impact of insulin with regard to behavioural aspects such as locomotion is unknown. METHODS To address insulin action in the brain with regard to cortical activity in distinct frequency bands and the behavioural consequences, the insulin signalling pathway was followed from the receptor to electrical activity and locomotion. Western blot analysis, electrocorticograms with intracerebroventricular (i.c.v.) application of insulin, and measurements of locomotor activity were performed in lean and obese, as well as Toll-like receptor (TLR) 2/4-deficient, mice. RESULTS We show that insulin application i.c.v. into lean mice was accompanied by a profound increase in cortical activity in the slow frequency range, while diet-induced obese mice displayed insulin resistance. In parallel, insulin administered i.c.v. increased locomotor activity in lean mice, whereas a phosphatidylinositol-3 (PI3) kinase inhibitor or obesity abolished insulin-mediated locomotion. A potential candidate that links insulin signalling to locomotion is the Kv1.3 channel that is activated by PI3-kinase. Pharmacological inhibition of Kv1.3 channels that bypassed insulin receptor activation promoted activity. Moreover, mice deficient in TLR2/4-dependent signalling displayed an increase in cortical activity in the slow frequency range that was correlated with improved spontaneous and insulin-mediated locomotor activity. CONCLUSIONS/INTERPRETATION Our data provide functional evidence for a direct effect of insulin on brain activation patterns in the slow frequency bands and locomotor activity in lean mice, while in obese mice, insulin-mediated locomotion is blunted and further aggravates physical inactivity.
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Affiliation(s)
- A M Hennige
- Department of Internal Medicine 4, University of Tuebingen, 72076, Tuebingen, Germany
| | - T Sartorius
- Department of Internal Medicine 4, University of Tuebingen, 72076, Tuebingen, Germany
- Institute of Pharmacy, Department of Pharmacology and Toxicology, University of Tuebingen, Tuebingen, Germany
| | - S Z Lutz
- Department of Internal Medicine 4, University of Tuebingen, 72076, Tuebingen, Germany
| | - O Tschritter
- Department of Internal Medicine 4, University of Tuebingen, 72076, Tuebingen, Germany
| | - H Preissl
- Institute of Medical Psychology and Behavioural Neurobiology, University of Tuebingen, Tuebingen, Germany
- Department of Obstetrics and Gynecology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - S Hopp
- Department of Internal Medicine 4, University of Tuebingen, 72076, Tuebingen, Germany
| | - A Fritsche
- Department of Internal Medicine 4, University of Tuebingen, 72076, Tuebingen, Germany
| | - H-G Rammensee
- Department of Immunology, Institute for Cell Biology, University of Tuebingen, Tuebingen, Germany
| | - P Ruth
- Institute of Pharmacy, Department of Pharmacology and Toxicology, University of Tuebingen, Tuebingen, Germany
| | - H-U Häring
- Department of Internal Medicine 4, University of Tuebingen, 72076, Tuebingen, Germany.
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