Tm. Lau et al., The effects of levonorgestrel implants on vascular endothelial growth factor expression in the endometrium, MOL HUM REP, 5(1), 1999, pp. 57-63
Vascular endothelial growth factor (VEGF) expression and the microvascular
density of the endometrium were studied in Norplant users and normal contro
ls, using immunohistochemistry on formalin-fixed paraffin-embedded endometr
ial sections. The VEGF staining index was quantified using computerized ima
ge analysis. The VEGF staining index between stages of the menstrual cycle
and between normal and Norplant endometria were compared. Norplant VEGF sta
ining index was analysed for correlation with microvascular density, durati
on of Norplant use, the number of bleeding/spotting days in the reference p
eriod up to 90 days prior to biopsy, and the length of time since the last
bleeding/spotting episode. The results showed that immunoreactive VEGF was
detected predominantly in endometrial glands but weakly expressed in the st
roma throughout the menstrual cycle, and also in Norplant users. Large vari
ation in the VEGF staining index between individuals was observed and no si
gnificant difference in the VEGF staining index was detected between stages
of the menstrual cycle for the glands and stroma. The glandular and stroma
l VEGF staining indices were significantly higher in Norplant than in norma
l endometrium (P <1x10(-4)). No correlation was found between the Norplant
VEGF staining index and endometrial microvascular density, duration of Norp
lant use, the number of bleeding/spotting days in the reference period, and
the length of time since the last bleeding/spotting episode. The VEGF stai
ning index was higher in glands than stroma for both normal and Norplant en
dometrium. The results suggest a differential control of endometrial glandu
lar Versus stromal VEGF expression, and possible positive effects of levono
rgestrel on VEGF expression.