Chemical messengers: a view from the gut

Area of Science:

• Gastroenterology
• Endocrinology
• Neuroscience

Background:

• Peptides traditionally known as gastrointestinal hormones are part of a larger system of regulatory substances.
• These substances are distributed widely in the body and utilize blood, neural, and paracrine pathways for signaling.
• Neural, endocrine, and paracrine cells can be collectively termed "regulator cells," and their messengers "regulins."

Purpose of the Study:

• To review the current understanding of peptides in the alimentary tract and pancreas.
• To categorize peptides based on established hormonal status and identify areas needing further research.
• To highlight the potential of specific antagonists in elucidating peptide functions.

Main Methods:

• Isolation and characterization of peptides from the alimentary tract and pancreas.
• Sequencing of identified peptides.
• Immunoreactivity assays for peptide identification.
• Review of existing evidence for hormonal status.

Main Results:

• Twenty peptides have been isolated from the alimentary tract and pancreas.
• Twelve peptides have been fully sequenced, four partially sequenced, and four identified solely by immunoreactivity.
• Five peptides (gastrin, gastric inhibitory peptide, glucagon, insulin, secretin) are considered established hormones.
• Evidence for the hormonal role of cholecystokinin, pancreatic polypeptide, and motilin is suggestive but incomplete.
• The physiological roles of the remaining 12 peptides are yet to be determined.

Conclusions:

• The broader category of
• regulins
• encompasses gastrointestinal peptides and other regulatory substances.
• While several peptides are confirmed hormones, a significant number require further functional elucidation.
• Development of specific peptide antagonists is crucial for advancing the understanding of their physiological roles.