Enteroglucagon

Enteroglucagon

Enteroglucagon is a peptide hormone that is primarily produced and secreted by the cells lining the small intestine. It plays a crucial role in regulating various physiological processes within the gastrointestinal tract. Enteroglucagon is derived from the proglucagon gene, which also gives rise to other important hormones such as glucagon and glucagon-like peptide-1 (GLP-1).

Structure and Synthesis

Enteroglucagon is a polypeptide consisting of 69 amino acids. It shares significant structural similarities with both glucagon and GLP-1. The primary structure of enteroglucagon includes a signal peptide, a glucagon-like peptide (GLP) domain, and a glucagon-like peptide-2 (GLP-2) domain.

Enteroglucagon is synthesized and processed within the enteroendocrine cells of the small intestine. Initially, the proglucagon gene is transcribed and translated into a larger precursor molecule called preproglucagon. This precursor is then cleaved by specific enzymes to produce enteroglucagon, GLP-1, and GLP-2.

Functions

Enteroglucagon exerts various physiological effects within the gastrointestinal tract, including:

1. **Regulation of Intestinal Motility**: Enteroglucagon acts as a potent stimulator of intestinal motility, promoting the movement of food through the digestive system. It increases the contraction of smooth muscles in the intestines, thereby enhancing the overall motility and transit time.

2. **Regulation of Intestinal Absorption**: Enteroglucagon also plays a role in modulating the absorption of nutrients within the small intestine. It promotes the uptake of glucose and amino acids, facilitating their transport across the intestinal epithelium.

3. **Regulation of Intestinal Secretion**: Enteroglucagon influences the secretion of various substances within the gastrointestinal tract. It stimulates the release of water and electrolytes, such as chloride and bicarbonate ions, into the intestinal lumen.

4. **Maintenance of Intestinal Barrier Function**: Enteroglucagon helps maintain the integrity of the intestinal barrier, which is crucial for preventing the entry of harmful substances into the bloodstream. It promotes the production of tight junction proteins, which play a key role in sealing the gaps between intestinal epithelial cells.

Clinical Significance

Enteroglucagon has been implicated in several gastrointestinal disorders and metabolic conditions. Dysregulation of enteroglucagon signaling has been associated with conditions such as irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and obesity.

Furthermore, enteroglucagon-based therapies have shown promise in the treatment of certain gastrointestinal disorders. For example, GLP-2 analogs, which mimic the effects of enteroglucagon, have been used to treat conditions like short bowel syndrome and intestinal failure.

References

1. Drucker DJ. The role of gut hormones in glucose homeostasis. J Clin Invest. 2007;117(1):24-32. doi:10.1172/JCI30076.

2. Holst JJ. The physiology of glucagon-like peptide 1. Physiol Rev. 2007;87(4):1409-1439. doi:10.1152/physrev.00034.2006.

See Also

• Glucagon
• Glucagon-like peptide-1
• Enteroendocrine cells
• Irritable bowel syndrome
• Inflammatory bowel disease
• Obesity
• Short bowel syndrome
• Intestinal failure