Mode of action of dopamine agonists
Dopamine agonists bind to the pituitary-specific D2 dopamine receptors on the cell membrane of prolactin-secreting cells, decreasing intracellular levels of cAMP and calcium. This process inhibits the synthesis and release of prolactin. An increase in cellular lysosomal activity causes involution of the rough endoplasmic reticulum and Golgi apparatus. The action of dopamine agonists on D1 dopamine receptors in the brain is the reason for the side effects of nausea and dizziness; dopamine agonists with more D2 specificity, such as cabergoline, are less likely to cause these side effects.