Vol. 273, Issue 5, G1044-G1050, November 1997
Neuronal release of endogenous dopamine from corpus of guinea
pig stomach
Kazuko
Shichijo1,
Yasuko
Sakurai-Yamashita2,
Ichiro
Sekine1, and
Kohtaro
Taniyama2
1 Department of Molecular
Pathology, Atomic Bomb Disease Institute, and
2 Department of Pharmacology
II, Nagasaki University School of Medicine, Nagasaki 852, Japan
Neuronal release
of endogenous dopamine was identified in mucosa-free preparations
(muscle layer including intramural plexus) from guinea pig stomach
corpus by measuring tissue dopamine content and dopamine release and by
immunohistochemical methods using a dopamine antiserum. Dopamine
content in mucosa-free preparations of guinea pig gastric corpus was
one-tenth of norepinephrine content. Electrical transmural stimulation
of mucosa-free preparations of gastric corpus increased the release of
endogenous dopamine in a frequency-dependent (3-20 Hz) manner. The
stimulated release of dopamine was prevented by either removal of
external Ca2+ or treatment with
tetrodotoxin. Dopamine-immunopositive nerve fibers surrounding choline
acetyltransferase-immunopositive ganglion cells were seen in the
myenteric plexus of whole mount preparations of gastric corpus even
after bilateral transection of the splanchnic nerve proximal to the
junction with the vagal nerve (section of nerves between the celiac
ganglion and stomach). Domperidone and sulpiride potentiated the
stimulated release of acetylcholine and reversed the dopamine-induced
inhibition of acetylcholine release from mucosa-free preparations.
These results indicate that dopamine is physiologically released from
neurons and from possible dopaminergic nerve terminals and regulates
cholinergic neuronal activity in the corpus of guinea pig stomach.
peripheral endogenous dopamine release; acetylcholine release; peripheral dopamine-immunopositive neurons; calcium-dependent dopamine
release; tetrodotoxin-sensitive dopamine release
