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Neural regulation of intestinal nutrient absorption
1Department of Internal Medicine, Faculty of Medicine, American University of Beirut, Beirut, Lebanon. fmourad@aub.edu.lb
Progress in Neurobiology
|August 23, 2011
Summary
The nervous system and gut interact to regulate nutrient absorption. Neural pathways involving capsaicin-sensitive primary afferent fibers and the vagus nerve control glucose, amino acid, and peptide uptake.
Area of Science:
- Neurogastroenterology
- Physiology
- Endocrinology
Background:
- The nervous system and gastrointestinal (GI) tract exhibit reciprocal interconnections and share signaling molecules.
- Digestion, enzyme secretion, and nutrient absorption are regulated by the neuro-endocrine system.
Purpose of the Study:
- To elucidate the role of neural mechanisms in regulating nutrient absorption in the GI tract.
- To investigate the influence of specific neuronal pathways and receptors on the absorption of glucose, amino acids, and peptides.
Main Methods:
- Review of existing literature on neuro-endocrine regulation of GI function.
- Analysis of neuronal reflexes, neurotransmitters, and hormonal pathways involved in nutrient absorption.
- Examination of the effects of adrenergic innervation and capsaicin-sensitive primary afferent (CSPA) fibers on nutrient transporters.
Main Results:
- Luminal glucose absorption is enhanced via CSPA fibers and insulin release, activating glucose transporters.
- Adrenergic innervation differentially affects glucose absorption via alpha and beta receptors.
- The vagus nerve regulates diurnal transporter expression and amino acid absorption, while CSPA fibers enhance peptide uptake via PEPT1.
Conclusions:
- Intrinsic and extrinsic neural mechanisms, involving redundant loops, are crucial for immediate and long-term control of intestinal nutrient absorption.
- While the intestinal mucosa is primary, neural regulation significantly modulates the absorption of carbohydrates, amino acids, and peptides.
- Neural innervation plays a minimal role in the absorption of fat digestion products.
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