Related Experiment Video
Updated: Jun 23, 2026
09:50
Application of Chronic Stimulation to Study Contractile Activity-induced Rat Skeletal Muscle Phenotypic Adaptations
Published on: January 25, 2018
Toll-like receptor signalling induced by endurance exercise
1Research Group in Muscle and Exercise Physiology, Institute of Neuroscience, Universite catholique de Louvain, Place Pierre de Coubertin-1, 1348 Louvain-la-Neuve, Belgium. marc.francaux@uclouvain.be
Summary
Toll-like receptors (TLRs) detect fatty acids, potentially causing insulin resistance. Exercise may reduce TLRs, offering protection against insulin resistance by modulating gene expression.
Area of Science:
- Immunology
- Metabolic research
- Cellular biology
Background:
- Toll-like receptors (TLRs) are key immune sensors recognizing microbial components.
- TLR2 and TLR4 in liver, adipose, and muscle tissues bind extracellular fatty acids.
- Fatty acid-induced TLR activation is linked to cellular stress, inflammation, and insulin resistance.
Purpose of the Study:
- To investigate the role of Toll-like receptors (TLRs) in insulin resistance.
- To explore how exercise influences TLR expression and its impact on metabolic pathways.
- To determine if TLR signaling mediates the effects of fatty acids on gene expression during exercise.
Main Methods:
- Review of existing literature on TLRs, fatty acids, and exercise.
- Analysis of TLR expression patterns in response to exercise.
- Examination of downstream signaling pathways activated by TLRs and fatty acids.
Main Results:
- Non-esterified fatty acids (NEFAs) binding to TLRs may contribute to insulin resistance development.
- Exercise appears to downregulate TLR expression, potentially conferring protection against insulin resistance.
- TLRs may mediate the activation of p38 and JNK pathways by NEFAs during endurance exercise, influencing key metabolic genes.
Conclusions:
- TLR activation by NEFAs is a potential mechanism contributing to insulin resistance.
- Exercise-induced downregulation of TLRs may be a protective mechanism against insulin resistance.
- Further research is needed to confirm TLR-dependent signaling in mediating exercise-induced gene expression changes by NEFAs.
Related Concept Videos
01:21Paracrine Signaling
Paracrine signaling allows cells to communicate with their immediate neighbors via secretion of signaling molecules. Such a signal can only trigger a response in nearby target cells because the signal molecules degrade quickly or are inactivated if not taken up. Prominent examples of paracrine signaling include nitric oxide signaling in blood vessels, synaptic signaling of neurons, the blood clotting system, tissue repair/wound healing, and local allergic skin reactions. Nitric oxide as a...
01:15Amplifying Signals via Second Messengers
Many receptor binding ligands are hydrophilic; they do not cross the cell membrane but bind to cell-surface receptors. Thus, their message must be relayed by second messengers present in the cell cytoplasm. There are several second messenger pathways, each with its own way of relaying information. For example, the G protein-coupled receptors can activate both phosphoinositol and cyclic AMP (cAMP) second messenger pathways. The phosphoinositol pathway is active when the receptor induces...
01:27Exercise and Muscle Performance
Exercise induces a range of adaptations in muscle tissue, depending on the type and duration of activity. Such physical training can be broadly categorized into two types: endurance exercises and resistance exercises.
Endurance exercises
Endurance exercises involve running, swimming, or cycling, which require repetitive movements with low force output. When a person engages in endurance exercise, a few noticeable changes occur in their skeletal muscles. For instance, the number of capillaries...
Endurance exercises
Endurance exercises involve running, swimming, or cycling, which require repetitive movements with low force output. When a person engages in endurance exercise, a few noticeable changes occur in their skeletal muscles. For instance, the number of capillaries...
01:26Cellular Adaptation II: Hypertrophy
Hypertrophy is the increase in the size of individual cells, resulting in the enlargement of a tissue or organ. Unlike hyperplasia, which involves an increase in cell number, hypertrophy is characterized by an increase in cell volume. This process often occurs in response to higher functional demand or hormonal stimulation, leading to the production of more structural proteins and organelles, thereby enhancing the cells' work capacity.There are two primary types of hypertrophy: physiological...
01:24Intracellular Signaling Cascades
Once a ligand binds to a receptor, the signal is transmitted through the membrane and into the cytoplasm. The continuation of a signal in this manner is called signal transduction. Signal transduction only occurs with cell-surface receptors, which cannot interact with most components of the cell, such as DNA. Only internal receptors can interact directly with DNA in the nucleus to initiate protein synthesis. When a ligand binds to its receptor, conformational changes occur that affect the...
01:22PI3K/mTOR/AKT Signaling Pathway
The mammalian target of rapamycin (mTOR) is a serine/threonine kinase that regulates growth, proliferation, and cell survival in response to hormones, growth factors, or nutrient availability. This kinase exists in two structurally and functionally distinct forms: mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). The first form (mTORC1) is composed of a rapamycin-sensitive Raptor and proline-rich Akt substrate, PRAS40. In contrast, mTORC2 consists of a rapamycin-insensitive companion...