Inhibitory effect of dopamine on gastric motility in rats.
BACKGROUND
There is disagreement with regard to the involvement of dopamine (DA) receptors in gastric motility. The mechanisms of the inhibitory effect of DA on rat gastric motility was investigated in association with acetylcholine (Ach) release in the present study.


METHODS
In vivo vagotomized, splanchnicectomized rats and control rats were used, and gastric movement was determined as the gastric motility index after DA administration. In vitro study of Ach release from the circular muscle strips of the gastric corpus was investigated after administration of domperidone, SCH23390, phentolamine, or propranolol.


RESULTS
In the in vivo study DA inhibited gastric motility in a dose-dependent manner. Vagotomy and splanchnicectomy had no effect on the inhibitory effect of DA. In vitro study DA inhibited [3H]-Ach release in a dose-dependent manner. The inhibitory effect of DA was antagonized by domperidone but not by phentolamine, propranolol, or SCH23390.


CONCLUSIONS
Inhibition of gastric motility by dopamine is independent of extrinsic innervation and seems to be mediated by DA2 receptors in the gastric wall.
Nagahata
Y
Y
First Dept. of Surgery, Kohe University School of Medicine, Japan.
Azumi
Y
Y
Kawakita
N
N
Wada
T
T
Saitoh
Y
Y
D000109:Acetylcholine / Q000378:metabolism*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D004294:Domperidone / Q000494:pharmacology; D004298:Dopamine / Q000008:administration & dosage / Q000494:pharmacology*; D018492:Dopamine Antagonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004558:Electric Stimulation; D005746:Gastric Emptying / Q000187:drug effects* / Q000502:physiology; D005769:Gastrointestinal Motility / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D001552:Benzazepines; D018492:Dopamine Antagonists; D004294:Domperidone; D011433:Propranolol; D000109:Acetylcholine; D004298:Dopamine; D010646:Phentolamine