Differential effects of L-dopa and apomorphine on glucagon secretion in man: evidence against central dopaminergic stimulation of glucagon.
In 6 normal subjects, L-dopa (500 mg PO) and apomorphine (0.6 mg sc) increased circulating growth hormone and suppressed prolactin levels in a parallel and quantitatively similar fashion, but only L-dopa induced a rise in plasma glucagon, glucose, and insulin levels. The failure of apomorphine to affect glucagon secretion, despite a substantial effect on growth hormone and prolactin, was also observed in insulin-dependent diabetics known to exhibit A-cell hyperresponsiveness to various stimuli. In view of the highly dissimilar molecular and pharmacologic characteristics of L-dopa and apomorphine, these data do not exclude a local dopaminergic effect of L-dopa at the pancreatic level, but strongly militate against a central dopaminergic pathway for glucagon stimulation.
D000328:Adult; D001058:Apomorphine; D001786:Blood Glucose / Q000378:metabolism; D003922:Diabetes Mellitus, Type 1 / Q000503:physiopathology; D005260:Female; D005934:Glucagon / Q000378:metabolism*; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood; D007980:Levodopa; D008297:Male; D011388:Prolactin / Q000097:blood; D011954:Receptors, Dopamine / Q000502:physiology
D001786:Blood Glucose; D007328:Insulin; D011954:Receptors, Dopamine; D007980:Levodopa; D011388:Prolactin; D013006:Growth Hormone; D005934:Glucagon; D001058:Apomorphine