Regulation of vascular endothelial growth factor-A and its soluble receptor sFlt-1 by luteinizing hormone in vivo: implication for ovarian follicle angiogenesis

Abstract

To determine in vivo whether LH supplementation during the late follicular phase induces ovarian follicle angiogenesis in humans, as reflected by vascular endothelial growth factor (VEGF)-A, its soluble receptor sFlt-1, and placental growth factor (PlGF) expression. Randomized, double-blind, placebo-controlled study. Academic tertiary care medical center. Twenty infertile, healthy women (aged 18-39 years) undergoing IVF. Administration of recombinant FSH after down-regulation and equal randomization of subjects to receive recombinant LH 75 IU/day or placebo when two or more follicles reached a mean diameter of 14 mm. Serum and follicular fluid (FF) VEGF-A, sFlt-1, and PlGF protein levels were measured. Recombinant LH increased both the FF VEGF-A/sFlt-1 ratio statistically significantly and PlGF/sFlt-1 insignificantly. Recombinant LH did not affect the serum VEGF/sFlt-1 ratio. Plasma levels of PlGF were undetectable. This in vivo study demonstrates for the first time in humans that LH induces ovarian follicular angiogenesis via modulation of VEGF-A and its soluble receptor sFlt-1 expression. A constant VEGF-A/sFlt-serum ratio may prevent adverse effects of VEGF-A. Because angiogenesis is essential during the periovulatory period, recombinant LH supplementation during the late follicular phase may improve ovulation induction outcome.