Quercetin Reduces Vascular Permeability in an Experimental Rat Model of Ovarian Hyperstimulation Syndrome: A Comparative Histochemical and Immunohistochemical Study with Cabergoline

This study investigated the effects of quercetin and cabergoline on ovarian histomorphology, biochemical changes and the vascular endothelial growth factor (VEGF)–pigment epithelium-derived factor (PEDF)- cyclooxygenase-2 (COX-2) axis in an experimental rat model of ovarian hiperstimulation syndrome (OHSS). Forty-two immature female Wistar rats were randomly divided into six groups: Control, OHSS, Quercetin, Cabergoline, OHSS+Quercetin, and OHSS+Cabergoline. Ovarian morphology was assessed by measuring ovarian weight and diameter. Histological examination was performed with hematoxylin and eosin (H&E) staining, and immunohistochemical analyses were conducted to determine VEGF, PEDF, and COX-2 expression in ovarian tissue. Vascular permeability was evaluated spectrophotometrically using Evans Blue dye extravasation, while serum TNF-α and estradiol levels were determined by ELISA. The OHSS group showed significantly increased ovarian weight and diameter compared with the other groups. VEGF and COX-2 expression were increased, whereas PEDF immunoreactivity was reduced in granulosa cells. In the treatment groups, VEGF and COX-2 expression were similar patterns, but PEDF expression was higher in the OHSS+Cabergoline group. Vascular permeability was significantly lower in the OHSS+Quercetin group than in the OHSS+Cabergoline group, indicating a stronger protective effect of quercetin on vascular integrity. Quercetin reduced vascular permeability, although most histological and biochemical parameters did not differ significantly between the treatment groups. These findings suggest that quercetin may exert protective effects on ovarian tissue, possibly through modulation of angiogenic balance and vascular permeability in experimantal OHSS.