Altered expressions of VEGF mRNA splice variants during progression of uterine-peritoneal adhesions in the rat

PROBLEM: Postoperative pelvic adhesions contribute to infertility, pelvic pain, bowel obstruction, and difficult reoperative procedures. METHOD OF STUDY: In the present study, a rat uterine-peritoneal adhesion model was developed to study the progression of adhesion formation during a course of 7 days following pelvic surgery. The distal 1 cm of each uterine horn and its adjacent peritoneum was abraded by six scratches with a scalpel blade, producing punctate bleeding. The scratched portion of uterine horn and the peritoneum was then held with Vicryl 3-0 to promote adhesion. The uterine tissue and the portion of peritoneum, held with suture, were then excised from a group of four rats, each at 6, 12, 24, 48, 72 hr and 5 and 7 days following surgery. Total RNA was isolated from these tissues and the expression pattern of different splice variants of vascular endothelial growth factors (VEGF) was examined using relative abundance reverse transcriptase polymerase chain reaction (RA-RT-PCR) method. RESULTS: Three known splice variants of VEGF mRNA (VEGF₁₂₀, VBGF₁₆₄ and VEGF₁₈₈), as well as an additional band (~510 bp), were amplified from these tissues. The relative abundance of known VEGF isoforms demonstrated altered expression during adhesion progression. When compared with noninjured uterine tissues, VEGF₁₂₀ and VEGF₁₈₈ demonstrated up-regulation during early stages of adhesion formation, whereas VEGF₁₆₄ rather demonstrated down-regulation 24 and 48 hr following surgery. CONCLUSIONS: The up-regulation of VEGF isoforms during the progression of uterine-peritoneal adhesion may be a compensatory mechanism regulating angiogenesis in order to provide nutrients and oxygen to the injured tissues.