Role of Dopaminergic Receptors on the Plasma Glucose Level in Mice

Dopamine (DA) is one of the predominant cathecolaminneurotransmitter in the mammalian brain playing it's role through the Dl-and D2 - Like recptors. The dopamine-induced hyperglycemia has already been reported, but the type ofreceptors involved in this process is still controversial.In this study we investigated the role of DI and 02-like receptors on the plasma glucose by specifc dopaminergic agonists and antagonists in the Albino mouse. Subcutaneous administration of apomorphine 0.25, 0.5, and lmg/kg) induced a dose-dependent hyperglycemia. This response was decreased by the blockade of the DI and 02 receptors by the SCH and sulpiride respectively. Activation of the 02-like receptors by high doses of the LY171555 produced a significant hyperglycemia which was reduced by the sulpiride. Stimulation of the D1like receptors by the specific Dl agonist, SKF38393, caused an increase in the plasma glucose which was not affected by the SCH. At low doses, apomorphine and SKF induced hypoglycemia in the second and third hours after the injection.In conclusion, dopaminergic system seems to have a dual stimulatory and inhibitory effect on the plasma glucose. The exact mechanisms of the stimulatory effect, mediated by the D2-like receptors, and the inhibitory effect ofthe dopaminergic system needs more investigation.