16K-Prolactin Inhibits Activation of Endothelial Nitric Oxide Synthase, Intracellular Calcium Mobilization, and Endothelium-Dependent Vasorelaxation

• Published in: Endocrinology (Philadelphia) 2004-12, Vol.145 (12), p.5714-5722
• Main Authors: Gonzalez, Carmen, Corbacho, Ana M, Eiserich, Jason P, Garcia, Celina, Lopez-Barrera, Fernando, Morales-Tlalpan, Veronica, Barajas-Espinosa, Alma, Diaz-Muñoz, Mauricio, Rubio, Rafael, Lin, Sue-Hwa, Martinez de la Escalera, Gonzalo, Clapp, Carmen
• Format: Article
• Language: English
• Subjects: Angiogenesis; Animals; Aorta; Biological and medical sciences; Blocking; Blood vessels; Bradykinin; Bradykinin - pharmacology; Calcium (intracellular); Calcium - metabolism; Calcium ions; Calcium mobilization; Calcium oxide; Cattle; Cell activation; Cell Division - drug effects; Cell proliferation; Cells, Cultured; Coronary vessels; Endothelial cells; Endothelium; Endothelium, Vascular - cytology; Endothelium, Vascular - drug effects; Endothelium, Vascular - enzymology; Fundamental and applied biological sciences. Psychology; Growth factors; Guinea Pigs; Humans; Intracellular; Male; Neovascularization, Physiologic - drug effects; Nitric oxide; Nitric Oxide - pharmacology; Nitric Oxide Synthase - antagonists & inhibitors; Nitric Oxide Synthase - metabolism; Nitric Oxide Synthase Type III; Nitric-oxide synthase; Prolactin; Prolactin - chemistry; Prolactin - pharmacology; Protein Structure, Tertiary; Rats; Rats, Sprague-Dawley; Rats, Wistar; Umbilical Veins - cytology; Vascular endothelial growth factor; Vascular Endothelial Growth Factor A - pharmacology; Vasoactive agents; Vasodilation; Vasodilation - drug effects; Vertebrates: endocrinology
• ISSN: 0013-7227; 1945-7170
• DOI: 10.1210/en.2004-0647

Activation of endothelial nitric oxide synthase (eNOS) and subsequent nitric oxide production (NO) are events that mediate the effect of important angiogenic, vasopermeability, and vasorelaxation factors, including vascular endothelial growth factor (VEGF), bradykinin (BK), and acetylcholine (ACh). The N-terminal 16-kDa fragment of prolactin (16K-PRL) acts on endothelial cells to inhibit angiogenesis both in vivo and in vitro. Here, we show that 16K-PRL inhibits VEGF-induced eNOS activation in endothelial cells. Inhibition of eNOS activation may mediate the antiangiogenic properties of 16K-PRL, because the NO donor (Z)-1-[2-(2-aminoethyl)- N-(2-ammonio-ethyl)amino]diazen-1-ium-1,2-diolate (DETANONOate) prevented 16K-PRL from blocking the VEGF-induced proliferation of endothelial cells. In addition, 16K-PRL inhibited eNOS activation by BK and blocked the BK-evoked transient increase in intracellular Ca2+ in endothelial cells. This finding suggests that 16K-PRL interferes with the mobilization of intracellular Ca2+, thereby inhibiting the Ca2+-dependent activation of eNOS. Blockage of eNOS activation can lead to inhibition of vasodilation. Consistently, 16K-PRL inhibited BK-induced relaxation of coronary vessels in isolated perfused guinea pig hearts. Moreover, 16K-PRL inhibited eNOS activation induced by ACh, and this action resulted in the inhibition of both ACh-evoked relaxation of coronary vessels in isolated perfused rat hearts and ACh-induced, endothelium-dependent relaxation of rat aortic segments. In conclusion, 16K-PRL can block the Ca2+-mediated activation of eNOS by three different vasoactive substances, and this action results in the inhibition of both angiogenesis and vasorelaxation.