Effects of Sildenafil in Nω-Nitro-l-Arginine Methyl Ester-Induced Intrauterine Growth Restriction in a Rat Model

OBJECTIVE: To assess the effect of sildenafil citrate in a rat model of Nω-nitro-l-arginine methyl ester (L-NAME)-induced intrauterine growth restriction (IUGR). STUDY DESIGN: An in vivo experimental study was conducted where 40 pregnant Sprague-Dawley rats were randomly assigned to receive either: (1) control, (2) L-NAME 50 mg/kg/d by gavage (days 14 to 19), (3) L-NAME and sildenafil 15 mg/kg/d by gavage, or (4) sildenafil (days 14 to 21). On day 21, a hysterotomy was performed and all fetuses (live and dead) were counted, examined, and weighed. The primary outcome measure was the difference in pup birth weight. RESULTS: The median number of live pups per dam was 11.5 (range: 1 to 15), 13.5 (2 to 17), 13.5 (7 to 16), and 11.5 (4 to 17) in controls, L-NAME, sildenafil, and combined drug groups, respectively (p = 0.02). Rats treated with L-NAME had a significantly higher number of stillbirths compared with control (p = 0.013) and sildenafil (p = 0.008) groups. L-NAME reduced pup birth weight compared with controls (4.53 ± 1.49 versus 5.65 ± 1.63 g, p < 0.001); this effect was more pronounced in the L-NAME and sildenafil groups (3.37 ± 1.25 g, p < 0.001). CONCLUSION: Our data indicate that sildenafil citrate does not ameliorate L-NAME-induced IUGR, and in the doses utilized in this study might even have a synergistic negative effect on pup birth weight.