Dopamine and insulin interact to modulate in vitro glucose transport in rat adipocytes

The in vitro effects of dopamine (DA) and insulin on -14C glucose oxidation (transport) in isolated rat adipocytes was studied. Low to intermediate concentrations of DA combined with low concentrations of insulin tended to stimulate glucose transport whilst high concentrations of DA combined with high concentrations of insulin produced inhibition of insulin stimulated glucose transport. The effect of DA on glucose transport was mediated via beta-adrenergic receptors, since propranolol, but not haloperidol or phentolamine, antagonised these effects of dopamine. These effects of dopamine on glucose transport may be relevant to the pathophysiology of Parkinson's disease and other neuropsychiatric conditions in which abnormalities of dopaminergic functions are thought to be of major pathogenic importance.