5‐HT activates neural reflexes regulating secretion in the guinea‐pig colon

• Published in: Neurogastroenterology and motility 1997-09, Vol.9 (3), p.181-186
• Main Authors: Cooke, H. J., Sidhu, M., Wang, Y.‐Z.
• Format: Article
• Language: English
• Subjects: Animals; Anti-Inflammatory Agents, Non-Steroidal - pharmacology; Chlorides - metabolism; Colon - innervation; Colon - physiology; Guinea Pigs; In Vitro Techniques; Intestinal Mucosa - innervation; Intestinal Mucosa - metabolism; Male; Neurons - physiology; Parasympathetic Nervous System - physiology; Piroxicam - pharmacology; Prostaglandins - metabolism; Reflex - physiology; Serotonin - physiology; Synaptic Transmission; Tachykinins - physiology
• ISSN: 1350-1925; 1365-2982
• DOI: 10.1046/j.1365-2982.1997.d01-41.x

The role of 5‐hydroxytryptamine (5‐HT) in neural reflexes regulating secretion was examined in muscle‐stripped segments of guinea‐pig colon set up in modified flux chambers. A 15‐μL pulse of 5‐HT (100 μM) to the mucosal bath (1.5 mL), which was continuously perfused, evoked an increase in short‐circuit current (Isc). The 5‐HT‐induced increase in Isc was inhibited by tetrodotoxin, N‐acetyl‐5‐hydroxytryptophyl‐5‐hydroxytryptophan amide (5‐HTP‐DP), GR82334 and atropine, but not by tropisetron. 5‐HTP‐DP reduced the response to a 5‐HT pulse over the concentration range of 1 nM to 1 μM. The Isc response to a 5‐HT pulse was unaffected by the cyclooxygenase inhibitor, piroxicam. This contrasted with a reduction in the Isc response to mucosal stroking with a brush by piroxicam. The results suggest that a 5‐HT pulse, like mucosal stroking, activates a secretory reflex that includes tachykinin and cholinergic neurons but, unlike mucosal stroking, does not release prostaglandins.