Abstract
ABSTRACTBackground: Gastrointestinal motility modulatory factors include substances of the intestinal content, such as polyamines and trace amines (TAs), the focus of this study.Methods: The amines of food, intestinal content and from faecal bacteria of Swiss mice were determined by HPLC and functionally characterised in isolated distal ileum and medial colon rings.Results: Mouse food and intestinal content contain polyamines (spermidine>putrescine>spermine) and TAs (isoamylamine>cadaverine). Intestinal bacteria mainly produce putrescine and cadaverine. The amines inhibited the spontaneous motility of the ileum (0.1-3 mM) and colon rings (0.01-3 mM, with lower IC50), with: spermine~isoamylamine~spermidine. Spermine inhibition was tetrodotoxin (TTX)-insensitive, while isoamylamine was TTX-sensitive, suggesting neural control. Mainly in the ileum, isoamylamine (3 mM) elicited acute effects modified by TTX, atropine and propranolol, and suppressed by spermine (3 mM), not being localized at the smooth muscle level. The amines assayed (3 mM), except putrescine and cadaverine in the ileum and isoamylamine in the colon, antagonised acetylcholine (ACh, 0.1 mM)-elicited phasic contractions. Isoamylamine and spermine in colon relaxed KCl (100 mM)-elicited tonic contractions, suggesting an effect on smooth muscle, but did not justify the suppression of motility caused by spermine and isoamylamine.Conclusions: Polyamines and TAs of the intestinal content might act on chemosensors and modulate intestinal peristalsis.
Highlights
Gastrointestinal motility drives segmentation and peristalsis, and has a complementary role in facilitating the digestion and absorption of nutrients
The polyamines putrescine, spermidine, and spermine are present in food, being significantly (ANOVA) more concentrated than those analysed in the chyme of the distal ileum and caecum and rectum faeces (p < 0.05)
Spermidine was more concentrated in caecum than ileum and faeces (p < 0.01), with this polyamine being more important than the others in the three intestinal segments analysed (p < 0.001)
Summary
Gastrointestinal motility drives segmentation and peristalsis, and has a complementary role in facilitating the digestion and absorption of nutrients This consists of well-coordinated spontaneous phasic contractions, occurring in the absence of extrinsic innervation, originating primarily in the pacemaker interstitial cells of Cajal (ICC). They are coupled with smooth muscle and platelet-derived growth factor receptor (PDGFR)-positive cells, forming a functional electrical syncytium, referred to as SIP [1,2]. Several biogenic amines, including polycationic molecules, polyamines, and primary amines derived from natural amino acids, are present in the intestinal lumen and incorporated in the chyme These come from the ingestion of a wide variety of foods [4,5], biliary and pancreatic secretions [6], and are produced by gut microbiota [7]. Methods: The amines of food, intestinal content and from faecal bacteria of Swiss mice were determined by HPLC and functionally characterised in isolated distal ileum and medial colon rings
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