Use of dopamine agonists to target angiogenesis in women with endometriosis

Endometriosis requires medical management during a woman's reproductive years. Most treatments aim to create a hypoestrogenic milieu, but for patients wishing to conceive, drugs that allow normal ovarian function are needed. Targeting angiogenesis, a hallmark of the disease, using dopamine agonists (DAs) is a promising strategy for endometriosis treatment. Herein, we review experimental and clinical data that investigate this concept. In experimental models of endometriosis, DAs (bromocriptine, cabergoline, quinagolide) downregulate proangiogenic and upregulate antiangiogenic pathways in inflammatory, endothelial and endometrial cells, blocking cellular proliferation and reducing lesion size. Impaired secretion of vascular endothelial growth factor (VEGF) and inactivation of its receptor type-2 are key events. VEGF inhibition also reduces nerve fiber density in lesions. In humans, quinagolide shows similar effects on lesions, and DAs reduce pain and endometrioma size. Moreover, a 20-fold downregulation of Serpin-1, the gene that encodes for plasminogen activator inhibitor 1 (PAI-1), has been observed after DAs treatment. Pentoxifylline, a PAI-1, increases pregnancy rates in women with endometriosis. Thus, the data support the use of DAs in the medical management of endometriosis to reduce lesion size and pain while maintaining ovulation. A combined approach of DAs and pentoxifylline is perhaps a smart way of targeting the disease from a completely different angle than current medical treatments.