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Responses of python gastrointestinal regulatory peptides to feeding
S M Secor1, D Fehsenfeld, J Diamond
1Department of Physiology, University of California School of Medicine, Los Angeles, CA 90095-1751, USA. ssecor@biology.as.ua.edu
Summary
Burmese pythons show significant changes in gastrointestinal hormones after feeding, with levels of cholecystokinin (CCK) and others rising dramatically. These findings suggest pythons are a valuable model for studying digestive peptide regulation.
Area of Science:
- Comparative physiology
- Gastroenterology
- Endocrinology
Background:
- Gastrointestinal (GI) function in reptiles, like the Burmese python (Python molurus), undergoes significant postfeeding changes.
- These physiological shifts are hypothesized to be regulated by GI hormones and neuropeptides.
Purpose of the Study:
- To investigate the changes in plasma and tissue concentrations of 11 GI hormones and neuropeptides in pythons following a meal.
- To explore the role of these peptides in regulating digestive responses in pythons.
Main Methods:
- Measurement of plasma and tissue concentrations of 11 GI hormones and neuropeptides in pythons.
- Analysis of peptide distribution in various GI tissues (stomach, pancreas, small intestine).
- Gel-permeation chromatography was used to determine molecular forms of the peptides.
Main Results:
- Circulating levels of cholecystokinin (CCK), glucose-dependent insulinotropic peptide (GIP), glucagon, and neurotensin increased significantly within 24 hours postfeeding.
- Specific peptides were localized to different GI tissues: neurotensin, somatostatin, motilin, and vasoactive intestinal peptide in the stomach; GIP and glucagon in the pancreas; CCK and substance P in the small intestine.
- Tissue concentrations of CCK, GIP, and neurotensin decreased postfeeding, while plasma levels rose, indicating peptide release.
Conclusions:
- Postfeeding release of GI peptides from tissues and their subsequent rise in plasma suggest a regulatory role in python digestive processes.
- The structural similarities between python and mammalian GI peptides, coupled with pronounced postfeeding responses, establish pythons as a compelling model for GI peptide research.