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Brown C, Pemberton S, Babin A, Abdulhameed N, Noonan C, Brown MB, Banks WA, Rhea EM. Insulin blood-brain barrier transport and interactions are greater following exercise in mice. J Appl Physiol (1985) 2022; 132:824-834. [PMID: 35175106 PMCID: PMC8917914 DOI: 10.1152/japplphysiol.00866.2021] [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] [Indexed: 11/22/2022] Open
Abstract
Exercise has multiple beneficial effects including improving peripheral insulin sensitivity, improving central function such as memory, and restoring a dysregulated blood-brain barrier (BBB). Central nervous system (CNS) insulin resistance is a common feature of cognitive impairment, including Alzheimer's disease. Delivery of insulin to the brain can improve memory. Endogenous insulin must cross the BBB to directly act within the CNS and this transport system can be affected by various physiological states and serum factors. Therefore, the current study sought to investigate whether exercise could enhance insulin BBB transport as a mechanism for the underlying benefits of exercise on cognition. We investigated radioactive insulin BBB pharmacokinetics following an acute bout of exercise in young, male and female CD-1 mice. In addition, we investigated changes in serum levels of substrates that are known to affect insulin BBB transport. Finally, we measured the basal level of a downstream protein involved in insulin receptor signaling in various brain regions as well as muscle. We found insulin BBB transport in males was greater following exercise, and in males and females to both enhance the level of insulin vascular binding and alter CNS insulin receptor signaling, independent of changes in serum factors known to alter insulin BBB transport.NEW & NOTEWORTHY Central nervous system (CNS) insulin and exercise are beneficial for cognition. CNS insulin resistance is present in Alzheimer's disease. CNS insulin levels are regulated by transport across the blood-brain barrier (BBB). We show that exercise can enhance insulin BBB transport and binding of insulin to the brain's vasculature in mice. There were no changes in serum factors known to alter insulin BBB pharmacokinetics. We conclude exercise could impact cognition through regulation of insulin BBB transport.
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Affiliation(s)
- Caitlin Brown
- 1Research and Development, Veterans Affairs Puget Sound Health Care System, Seattle, Washington
| | - Sarah Pemberton
- 1Research and Development, Veterans Affairs Puget Sound Health Care System, Seattle, Washington,2Department of Biology, University of Washington, Seattle, Washington
| | - Alice Babin
- 1Research and Development, Veterans Affairs Puget Sound Health Care System, Seattle, Washington
| | - Noor Abdulhameed
- 1Research and Development, Veterans Affairs Puget Sound Health Care System, Seattle, Washington,2Department of Biology, University of Washington, Seattle, Washington
| | - Cassidy Noonan
- 1Research and Development, Veterans Affairs Puget Sound Health Care System, Seattle, Washington,2Department of Biology, University of Washington, Seattle, Washington
| | - Mary Beth Brown
- 3Division of Physical Therapy, Department of Rehabilitation Medicine, University of Washington, Seattle, Washington
| | - William A. Banks
- 4Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, Washington,5Geriatric Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, Washington
| | - Elizabeth M. Rhea
- 4Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, Washington,5Geriatric Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, Washington
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Banks WA, Noonan C, Rhea EM, M. Rhea E. Evidence for an alternative insulin transporter at the blood-brain barrier. AGING PATHOBIOLOGY AND THERAPEUTICS 2022; 4:100-108. [PMID: 36644126 PMCID: PMC9837797 DOI: 10.31491/apt.2022.12.100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Accumulating evidence suggests there is an alternative insulin transporter besides the insulin receptor at the blood-brain barrier (BBB), responsible for shuttling insulin from the circulation into the brain. In this review, we summarize key features of the BBB and what makes it unique compared to other capillary beds; summarize what we know about insulin BBB transport; provide an extensive list of diseases, physiological states, and serum factors tested in modifying insulin BBB transport; and lastly, highlight potential alternative transport systems that may be involved in or have already been tested in mediating insulin BBB transport. Identifying the transport system for insulin at the BBB would aide in controlling central nervous system (CNS) insulin levels in multiple diseases and conditions including Alzheimer's disease (AD) and obesity, where availability of insulin to the CNS is limited.
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Affiliation(s)
- William A. Banks
- Department of Medicine, Division of Gerontology and Geriatric Medicine, University of Washington, Seattle, WA 98195, USA.,Geriatric Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA
| | - Cassidy Noonan
- Research and Development, Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA.,University of Washington, Seattle, WA 98195, USA
| | - Elizabeth M. Rhea
- Department of Medicine, Division of Gerontology and Geriatric Medicine, University of Washington, Seattle, WA 98195, USA.,Geriatric Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA.,Corresponding author: Elizabeth M. Rhea, Mailing address: 1660 S. Columbian Way, Seattle, WA 98108, USA.
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The Blood-Brain Barrier, Oxidative Stress, and Insulin Resistance. Antioxidants (Basel) 2021; 10:antiox10111695. [PMID: 34829566 PMCID: PMC8615183 DOI: 10.3390/antiox10111695] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 10/22/2021] [Accepted: 10/25/2021] [Indexed: 12/12/2022] Open
Abstract
The blood–brain barrier (BBB) is a network of specialized endothelial cells that regulates substrate entry into the central nervous system (CNS). Acting as the interface between the periphery and the CNS, the BBB must be equipped to defend against oxidative stress and other free radicals generated in the periphery to protect the CNS. There are unique features of brain endothelial cells that increase the susceptibility of these cells to oxidative stress. Insulin signaling can be impacted by varying levels of oxidative stress, with low levels of oxidative stress being necessary for signaling and higher levels being detrimental. Insulin must cross the BBB in order to access the CNS, levels of which are important in peripheral metabolism as well as cognition. Any alterations in BBB transport due to oxidative stress at the BBB could have downstream disease implications. In this review, we cover the interactions of oxidative stress at the BBB, how insulin signaling is related to oxidative stress, and the impact of the BBB in two diseases greatly affected by oxidative stress and insulin resistance: diabetes mellitus and Alzheimer’s disease.
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