Vascular endothelial growth factor (VEGF) and inducible nitric oxide synthase (iNOS) immunoreactivities in rat ovaries and uterine tubes after tubal ligation: a controlled immunohistochemical study

Abstract

Objective To evaluate the effects of tubal ligation on ovarian and tubal tissues by means of immunohistochemical evaluation of two hypoxia related mediators: vascular endothelial growth factor (VEGF) and inducible nitric oxide synthase (iNOS).

Design Fourteen Sprague-Dawley female rats were divided into two groups: a tubal ligation (Pomeroy technique) was carried out on rats in group 1 (n = 7) whereas those in group 2 served as controls (n = 7). Salpingo-oophorectomy was performed in group 1 during the second oestrous period following tubal ligation. Rats in group 2 were submitted to a salpingo-oophorectomy, as well. VEGF and iNOS immunoreactivities in ovarian and tubal tissues were evaluated by means of immunohistochemistry. Immunohistochemical scores and number of antral follicles were compared.

Results In the ovary, VEGF immunoreactivity was significantly more intense in the granulosa (p = 0.002) and the theca cells (p = 0.001) of rats in group 1 but, in ovarian medulla (p = 0.259) and germinal epithelium (p = 0.209), it was not significantly different from that of rats in group 2. The iNOS immunoreactivity in ovarian granulosa cells (p = 0.073) and germinal epithelial cells (p = 0.805) did not differ between the two groups. The cytoplasmic VEGF (p = 0.001) and iNOS (p = 0.017) immunoreactivities in the uterine tube, were significantly more intense in group 1. However, VEGF immunoreactivity in the lamina propria of the uterine tube (p = 0.209) was of similar intensity in both groups.

Conclusion Tubal ligation may lead to supraphysiological hypoxia as evidenced by increased VEGF and iNOS immunoreactivities in ovarian and tubal tissues.

Keywords:

• Tubal ligation
• VEGF
• iNOS
• Rat model
• Pomeroy technique
• Immunohistochemical