Dopaminergic regulation of glucose-induced insulin secretion through dopamine D2 receptors in the pancreatic islets in vitro.
The stimulatory effect of dopamine through dopamine D2 receptor on glucose-induced insulin secretion was studied in the pancreatic islets in vitro. Dopamine significantly stimulated insulin secretion at a concentration of 10-8 M in the presence of high glucose (20 mM). The higher concentrations of dopamine (10(-7)-10(-4)) inhibited glucose-induced insulin secretion in the presence of both 4 mM and 20 mM glucose. Stimulatory and inhibitory effect of dopamine on glucose-induced insulin secretion was reverted by the addition of dopamine D2 receptor antagonists such as butaclamol and sulpiride. Norepinephrine (NE) at 10(-4) M concentration inhibited the dopamine uptake as well as its stimulatory effect at 10(-8) M concentration on glucose induced insulin secretion. Our results suggest that dopamine exerts a differential effect on glucose-induced insulin secretion through dopamine D2 receptor and it is essential for the regulation of glucose-induced insulin secretion by pancreatic islets.
Shankar
Eswar
E
Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Kochi, India.
Santhosh
K T
KT
Paulose
C S
CS
D000818:Animals; D004298:Dopamine / Q000502:physiology*; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D005947:Glucose / Q000502:physiology*; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D017448:Receptors, Dopamine D2 / Q000502:physiology*; D046509:Tissue Culture Techniques
D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D007328:Insulin; D017448:Receptors, Dopamine D2; D005947:Glucose; D004298:Dopamine