Insulin on the brain: The role of central insulin signalling in energy and glucose homeostasis

Author(s):  
Cait A. Beddows ◽  
Garron T. Dodd
2018 ◽  
Vol 107 (2) ◽  
pp. 181-195 ◽  
Author(s):  
Maud Gratuze ◽  
Aurélie Joly-Amado ◽  
Didier Vieau ◽  
Luc Buée ◽  
David Blum

Alzheimer disease (AD) is a progressive neurodegenerative disorder mainly characterized by cognitive deficits and neuropathological changes such as Tau lesions and amyloid plaques, but also associated with non-cognitive symptomatology. Metabolic and neuroendocrine abnormalities, such as alterations in body weight, brain insulin impairments, and lower brain glucose metabolism, which often precede clinical diagnosis, have been extensively reported in AD patients. However, the origin of these symptoms and their relation to pathology and cognitive impairments remain misunderstood. Insulin is a hormone involved in the control of energy homeostasis both peripherally and centrally, and insulin-resistant state has been linked to increased risk of dementia. It is now well established that insulin resistance can exacerbate Tau lesions, mainly by disrupting the balance between Tau kinases and phosphatases. On the other hand, the emerging literature indicates that Tau protein can also modulate insulin signalling in the brain, thus creating a detrimental vicious circle. The following review will highlight our current understanding of the role of insulin in the brain and its relation to Tau protein in the context of AD and tauopathies. Considering that insulin signalling is prone to be pharmacologically targeted at multiple levels, it constitutes an appealing approach to improve both insulin brain sensitivity and mitigate brain pathology with expected positive outcome in terms of cognition.


Author(s):  
Sofia Khanam

We have learned over the last several decades that the brain is an important target for insulin action. In central nervous system (CNS) it mainly affects feeding behaviour and various aspects of memory and cognition. Insulin signalling in CNS has emerged as a novel field of research since decreases brain insulin levels and signalling were associated to impaired learning, memory and age-related neurodegenerative diseases. Alterations of these functional activities may contribute to the manifestation of several clinical entities, such as central insulin resistance, type 2 diabetes mellitus (T2DM) and Alzheimer’s disease (AD). A close alliance between T2DM and AD has been reported, to the extent that AD is twice more frequent in diabetic patients. There are links between T2DM and AD through mitochondrial alterations and oxidative stress, altered energy and glucose metabolism, cholesterol modifications, dysfunctional protein O-GlcNAcylation, formation of amyloid plaques, altered Aβ metabolism and tau hyperphosphorylation. Herewith, we aim to integrate the metabolic, neuromodulatory, and neuroprotective roles of insulin in two age-related pathologies: T2DM and AD, both in terms of intracellular signalling and potential therapeutic approach.


Diabetes ◽  
2017 ◽  
Vol 66 (7) ◽  
pp. 1758-1765 ◽  
Author(s):  
Jennifer D. Deem ◽  
Kenjiro Muta ◽  
Jarrad M. Scarlett ◽  
Gregory J. Morton ◽  
Michael W. Schwartz

Physiology ◽  
2009 ◽  
Vol 24 (3) ◽  
pp. 159-170 ◽  
Author(s):  
Carol K. L. Lam ◽  
Madhu Chari ◽  
Tony K. T. Lam

The past decade has hosted a remarkable surge in research dedicated to the central control of homeostatic mechanisms. Evidence indicates that the brain, in particular the hypothalamus, directly senses hormones and nutrients to initiate behavioral and metabolic responses to control energy and nutrient homeostasis. Diabetes is chiefly characterized by hyperglycemia due to impaired glucose homeostatic regulation, and a primary therapeutic goal is to lower plasma glucose levels. As such, in this review, we highlight the role of the hypothalamus in the regulation of glucose homeostasis in particular and discuss the cellular and molecular mechanisms by which this neural pathway is orchestrated.


2015 ◽  
Vol 75 (1) ◽  
pp. 61-72 ◽  
Author(s):  
Guy A. Rutter ◽  
Pauline Chabosseau ◽  
Elisa A. Bellomo ◽  
Wolfgang Maret ◽  
Ryan K. Mitchell ◽  
...  

Zinc is an important micronutrient, essential in the diet to avoid a variety of conditions associated with malnutrition such as diarrhoea and alopecia. Lowered circulating levels of zinc are also found in diabetes mellitus, a condition which affects one in twelve of the adult population and whose treatments consume approximately 10 % of healthcare budgets. Zn2+ ions are essential for a huge range of cellular functions and, in the specialised pancreatic β-cell, for the storage of insulin within the secretory granule. Correspondingly, genetic variants in the SLC30A8 gene, which encodes the diabetes-associated granule-resident Zn2+ transporter ZnT8, are associated with an altered risk of type 2 diabetes. Here, we focus on (i) recent advances in measuring free zinc concentrations dynamically in subcellular compartments, and (ii) studies dissecting the role of intracellular zinc in the control of glucose homeostasis in vitro and in vivo. We discuss the effects on insulin secretion and action of deleting or over-expressing Slc30a8 highly selectively in the pancreatic β-cell, and the role of zinc in insulin signalling. While modulated by genetic variability, healthy levels of dietary zinc, and hence normal cellular zinc homeostasis, are likely to play an important role in the proper release and action of insulin to maintain glucose homeostasis and lower diabetes risk.


2019 ◽  
Vol 129 (8) ◽  
pp. 3035-3037 ◽  
Author(s):  
Jenny M. Brown ◽  
Jarrad M. Scarlett ◽  
Michael W. Schwartz

Author(s):  
J.E. Johnson

Although neuroaxonal dystrophy (NAD) has been examined by light and electron microscopy for years, the nature of the components in the dystrophic axons is not well understood. The present report examines nucleus gracilis and cuneatus (the dorsal column nuclei) in the brain stem of aging mice.Mice (C57BL/6J) were sacrificed by aldehyde perfusion at ages ranging from 3 months to 23 months. Several brain areas and parts of other organs were processed for electron microscopy.At 3 months of age, very little evidence of NAD can be discerned by light microscopy. At the EM level, a few axons are found to contain dystrophic material. By 23 months of age, the entire nucleus gracilis is filled with dystrophic axons. Much less NAD is seen in nucleus cuneatus by comparison. The most recurrent pattern of NAD is an enlarged profile, in the center of which is a mass of reticulated material (reticulated portion; or RP).


1969 ◽  
Vol 21 (02) ◽  
pp. 294-303 ◽  
Author(s):  
H Mihara ◽  
T Fujii ◽  
S Okamoto

SummaryBlood was injected into the brains of dogs to produce artificial haematomas, and paraffin injected to produce intracerebral paraffin masses. Cerebrospinal fluid (CSF) and peripheral blood samples were withdrawn at regular intervals and their fibrinolytic activities estimated by the fibrin plate method. Trans-form aminomethylcyclohexane-carboxylic acid (t-AMCHA) was administered to some individuals. Genera] relationships were found between changes in CSF fibrinolytic activity, area of tissue damage and survival time. t-AMCHA was clearly beneficial to those animals given a programme of administration. Tissue activator was extracted from the brain tissue after death or sacrifice for haematoma examination. The possible role of tissue activator in relation to haematoma development, and clinical implications of the results, are discussed.


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