Accumulation of dopamine in mouse pancreatic B-cells following injection of L-DOPA. Localization to secretory granules and inhibition of insulin secretion

Diabetologia. 1977 Apr;13(2):117-24. doi: 10.1007/BF00745138.


Accumulation and subcellular localization of dopamine (DA) in pancreatic B-cells and its effects on insulin secretion were investigated in mice following a single injection of L-3,4-dihydroxyphenylalanine (L-DOPA). Electron microscopic autoradiography showed that 3H-DA formed from administered 3H-DOPA was present over B-cells as well as over other types of islet cells. Pretreatment of the animals with a decarboxylase inhibitor greatly reduced the number of autoradiographic grains. In the B-cells the 3H-DA-grains were associated with the secretory granules. The location of the label may suggest an incorporation in the periphery of the beta-granule, rather than in the dense core, supposed to contain insulin. Accumulation of DA in the B-cells following L-DOPA administration was found to inhibit partially the insulin secretory response to different insulin secretagogues (glucose, glibenclamide and L-isopropylnoradrenaline (L-IPNA). Treatment with monoamine oxidase inhibitor + L-DOPA induced an almost total suppression of L-IPNA-stimulated insulin secretion, whereas glucose-induced insulin release was still only partially inhibited. Pretreatment with a decarboxylase inhibitor abolished the effects of L-DOPA. It is suggested that intracellularly accumulated DA in the B-cell exerts an inhibitory action on insulin releasing mechanisms induced by different secretagogues and that this action might involve interference with a calcium translocation process at the level of the secretory granule.

MeSH terms

  • Animals
  • Benserazide / pharmacology
  • Cytoplasmic Granules / analysis
  • Dihydroxyphenylalanine / pharmacology*
  • Dopamine / metabolism*
  • Female
  • Glucose / pharmacology
  • Glyburide / pharmacology
  • Insulin / metabolism*
  • Insulin Secretion
  • Islets of Langerhans / metabolism*
  • Islets of Langerhans / ultrastructure
  • Isoproterenol / pharmacology
  • Mice
  • Microscopy, Electron
  • Pargyline / pharmacology


  • Insulin
  • Dihydroxyphenylalanine
  • Benserazide
  • Pargyline
  • Glucose
  • Isoproterenol
  • Glyburide
  • Dopamine