TY - JOUR
T1 - Effect of putative carcinoid mediators on gastric and small bowel transit in rats and the role of 5‐HT receptors
AU - VALDOVINOS, M. A.
AU - THOMFORDE, G. M.
AU - CAMILLERI, M.
PY - 1993/2
Y1 - 1993/2
N2 - Whereas serotonin and substance P stimulate in‐vivo and in‐vitro myoelectric activity in the small intestine, their effects on transit are unclear. We used a validated in‐vivo transit model in the chloral hydrate‐anaesthetized rat to study the effects of serotonin, substance P and motilin, three putative mediators of carcinoid diarrhoea, on transit through the upper digestive tract. Intra‐arterial serotonin accelerated gastric emptying of a radiolabeled liquid, while motilin accelerated overall upper gastrointestinal transit. Substance P slowed overall upper gastrointestinal transit without altering gastric emptying. The antagonists to serotonin receptor subtypes, R‐zacopride (5‐HT3) and ketanserin (5‐HT2), also accelerated rat gastric emptying of liquids; in contrast, a 5‐HT4 agonist, SC53116, resulted in a less pronounced effect on gastric emptying at the dose tested. We conclude that circulating substance P is unlikely to be an important accelerator of transit through the upper digestive tract; in contrast, hyperserotoninaemia significantly accelerates transit through the stomach, and 5‐HT2 and 5‐HT3 receptor subtypes may play a role in the motor effects of serotonin in the stomach.
AB - Whereas serotonin and substance P stimulate in‐vivo and in‐vitro myoelectric activity in the small intestine, their effects on transit are unclear. We used a validated in‐vivo transit model in the chloral hydrate‐anaesthetized rat to study the effects of serotonin, substance P and motilin, three putative mediators of carcinoid diarrhoea, on transit through the upper digestive tract. Intra‐arterial serotonin accelerated gastric emptying of a radiolabeled liquid, while motilin accelerated overall upper gastrointestinal transit. Substance P slowed overall upper gastrointestinal transit without altering gastric emptying. The antagonists to serotonin receptor subtypes, R‐zacopride (5‐HT3) and ketanserin (5‐HT2), also accelerated rat gastric emptying of liquids; in contrast, a 5‐HT4 agonist, SC53116, resulted in a less pronounced effect on gastric emptying at the dose tested. We conclude that circulating substance P is unlikely to be an important accelerator of transit through the upper digestive tract; in contrast, hyperserotoninaemia significantly accelerates transit through the stomach, and 5‐HT2 and 5‐HT3 receptor subtypes may play a role in the motor effects of serotonin in the stomach.
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U2 - 10.1111/j.1365-2036.1993.tb00070.x
DO - 10.1111/j.1365-2036.1993.tb00070.x
M3 - Article
C2 - 7679934
AN - SCOPUS:0027393592
SN - 0269-2813
VL - 7
SP - 61
EP - 66
JO - Alimentary pharmacology & therapeutics
JF - Alimentary pharmacology & therapeutics
IS - 1
ER -