Thierry Alquier, professor in the Department of Medicine at Université de Montréal
Photo Credit: Chum
Scientific Frontline: Extended "At a Glance" Summary: Neuronal Lipid Metabolism
The Core Concept: Neurons actively maintain and utilize lipid reserves in the form of lipid droplets for cellular energy and structural maintenance. This discovery fundamentally challenges the long-held scientific consensus that neurons rely almost exclusively on glucose to power their high metabolic demands.
Key Distinction/Mechanism: Historically, lipids in healthy neurons were considered to serve strictly structural roles, such as maintaining cell membranes, while the accumulation of lipid droplets was viewed primarily as a pathological marker for neurodegenerative conditions like Alzheimer's disease. The newly identified mechanism demonstrates that healthy neurons continuously form and consume these triglyceride-rich droplets to fuel mitochondria and support the endoplasmic reticulum.
Major Frameworks/Components:
- Lipid Droplet Functionality: Intracellular organelles, composed primarily of triglycerides, function as dynamic fatty acid reservoirs for ongoing cellular repair and energy.
- Evolutionary Conservation: The functional use of lipid droplets in neurons is conserved across vast evolutionary distances, demonstrated in both invertebrate fruit flies (AKH neuroendocrine neurons) and vertebrate mice (AgRP hypothalamic neurons).
- Organelle Support: Lipid stores directly supply bioenergetic fuel to mitochondria and provide necessary components to the endoplasmic reticulum for protein synthesis.
- Sex-Dimorphic Metabolic Impact: Genetically blocking access to these lipid stores directly alters systemic energy reserves, food intake, and body weight, with effects presenting much more prominently in male subjects.
Branch of Science: Neuroscience, Cellular Biology, Biochemistry, and Metabolic Endocrinology.
Future Application: These findings open new therapeutic avenues for investigating and treating metabolic conditions such as obesity, type 2 diabetes, and specific brain metabolism disorders. Furthermore, the sex-specific differences in lipid utilization provide a framework for developing highly targeted, sex-differentiated metabolic therapies.
Why It Matters: This research revises classical models of brain bioenergetics. By establishing that neurons utilize a more diverse metabolic fuel profile than previously recognized, it highlights a critical, underappreciated cellular mechanism that directly influences both central nervous system health and whole-body systemic energy regulation.
The brain is the body’s command center, and neurons are the workhorses that carry out its commands. They transmit signals that regulate many bodily functions, including key metabolic processes such as appetite, body weight, and energy expenditure.
But how do neurons power all this activity?
Until now, it was thought they relied primarily on glucose. However, a new Canadian study published in Nature Metabolism challenges this view, showing that neurons maintain lipid reserves in the form of lipid droplets, which are crucial to their functioning.
The study was supervised by Thierry Alquier, a professor in Université de Montréal’s Faculty of Medicine and researcher at the UdeM-affiliated CHUM Research Centre (CRCHUM), and Elizabeth Rideout, an associate professor in the Faculty of Medicine at the University of British Columbia. Doctoral students Romane Manceau and Danie Majeur worked on the study.
Role poorly understood
For years, scientists believed that lipids in neurons primarily serve a structural role, maintaining membranes and supporting internal functions.
While studies had identified a specific storage form known as lipid droplets—organelles composed mainly of triglycerides—they were mostly observed in pathological contexts, particularly in neurodegenerative diseases such as Alzheimer’s. Their presence in healthy neurons and role in everyday neuronal function were poorly understood.
Using a combination of animal models and genetic tools, Alquier and his team demonstrated that lipid droplets are present and functional in the neurons of species separated by vast evolutionary distances, from invertebrates to vertebrates.
To investigate the role of lipid droplets in neuronal activity, he and his co-researchers focused on two types of neurons involved in energy balance: AgRP hypothalamic neurons in mice and AKH neuroendocrine neurons in fruit flies.
The scientists identified the enzymes and proteins that regulate the formation and use of lipid droplets in these neurons. By introducing genetic mutations that disrupted these components, the research team blocked the neurons’ access to their lipid stores.
A direct impact
This had a direct impact on metabolic parameters, including energy reserves, food intake, and body weight. For example, mice exhibited altered food intake and energy expenditure, while fruit flies accumulated fat.
Interestingly, these effects were more pronounced in males, suggesting a sex-related dimension to energy regulation.
What exactly do these lipid droplets do?
Firstly, they act as a reservoir of fatty acids, providing the essential building blocks needed to repair and maintain cell membranes. Even more importantly, they supply energy to the mitochondria—the cell’s “powerhouses”—and help maintain the endoplasmic reticulum, which is involved in protein synthesis.
A critical energy source
The study's co-authors note that their findings add to a growing body of research suggesting that lipid droplets serve as a critical, ongoing energy source for neurons, and highlight a previously underappreciated role they play.
The results open new avenues for investigating the droplets' contribution to neuronal metabolism and synaptic function, and pave the way for further research on the role of neuronal lipid metabolism in obesity, type 2 diabetes and certain brain metabolism disorders, as well as why its disruption affects males and females differently, the scientists say.
Funding: Their research was funded in part by the Canadian Institutes of Health Research, the Natural Sciences and Engineering Research Council of Canada, and the Fonds de recherche du Québec–Santé
Published in journal: Nature Metabolism
Authors: Romane Manceau, Celena M. Cherian, Danie Majeur, Colin J. Miller, Jasper D. Fisher, Frédérick Boisjoly, J. Beatrice Liston, Jennifer A. Bako, Lianna W. Wat, Charlotte F. Chao, Audrey Labarre, Serena Hollman, Sanjana Prakash, Sébastien Audet, Lewis Depaauw-Holt, Benjamin Rogers, Anthony Bosson, Puja Biswas, Joyce J. Y. Xi, Catrina A. S. Callow, Niyoosha Yoosefi, Neele Schikora, Niki Shahraki, Yi Han Xia, Alisa Hui, Jared VanderZwaag, Khalil Bouyakdan, Demetra Rodaros, Pavel Kotchetkov, Caroline Daneault, Ghazal Fallahpour, Martine Tetreault, Marie-Ève Tremblay, Matthieu Ruiz, Baptiste Lacoste, J. Alex Parker, Ciaran Murphy-Royal, Tao Huan, Stephanie Fulton, Elizabeth J. Rideout, and Thierry Alquier
Source/Credit: Université de Montréal | Mylène Tremblay
Reference Number: ns041426_01