After the 12<sup>th</sup> week, half of the Control and HF rats received a single dose of IGF-1 (50 μg/kg, i.p.), while the other half was placebo-treated, and after 24 h the animals were euthanized.<h4>Results</h4>The <i>in vivo</i> administration of IGF-1 led to a significant increase in nitric oxide (NO), iNOS gene and protein expression, endothelial nitric oxide synthase (eNOS) gene, ERK1/2, and nuclear factor kappa B (NFkB) levels in Control rats. Here, NOS2 is linked to hydrops fetalis.