Peripheral dopamine D2-like receptors have a regulatory effect on carbachol-, histamine- and pentagastrin-stimulated gastric acid secretion.
It has been documented that dopamine, an important regulator of gastric function in the brain-gut axis, has an inhibitory effect on the gastric acid secretion. It has also been suggested that dopamine D1, D2 and D5 receptor proteins are present in the gastrointestinal tract from the stomach through to the distal colon. Therefore, we hypothesized that peripheral D2 receptors may be involved in the control of stimulated gastric acid secretion. To address this question, we examined the effect of quinpirole, a selective D2 receptor-like agonist, and domperidone, a peripheral D2 receptor antagonist, on rat gastric acid secretion. Quinpirole (0.0001-0.5 mg/kg, i.p.) was administered simultaneously with intravenous infusions of histamine, pentagastrin, and carbachol. In some experiments, domperidone (3 and 7 mg/kg) was administered 30 min before quinpirole injection. We found that intraperitoneal injection of quinpirole (0.0001-0.5 mg/kg) suppressed stimulated gastric acid secretion induced by histamine (0.08 mg/100 g per h), pentagastrin (1 microg/100 g per h) and carbachol (4 microg/100 g per h) in a dose-dependent manner. This inhibitory effect of quinpirole persisted until the end of the experiments (90-120 min) and was completely suppressed by domperidone (7 mg/kg). In conclusion, the results of the present study suggest that peripheral D2-like receptors have an inhibitory effect on histaminergic-, pentagastrin- and cholinergic-stimulated gastric acid secretion. This inhibitory effect may be mediated by enteric dopaminergic neurons and/or non-neuronal membranes.
Eliassi
Afsaneh
A
Neuroscience Research Centre and Department of Physiology, Shahid Beheshti University (Medical Campus), Tehran, Iran. afeliassi@gmail.com
Aleali
Fereshteh
F
Ghasemi
Taieb
T
D000818:Animals; D002217:Carbachol / Q000494:pharmacology*; D005744:Gastric Acid / Q000378:metabolism*; D005765:Gastrointestinal Agents / Q000494:pharmacology; D006632:Histamine / Q000494:pharmacology*; D008297:Male; D010418:Pentagastrin / Q000494:pharmacology*; D019257:Quinpirole / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D017448:Receptors, Dopamine D2 / Q000819:agonists / Q000502:physiology*; D013997:Time Factors
D005765:Gastrointestinal Agents; D017448:Receptors, Dopamine D2; C113776:dopamine D2L receptor; D019257:Quinpirole; D006632:Histamine; D002217:Carbachol; D010418:Pentagastrin