Immunohistochemical demonstration of blood vessels alpha-actin down-regulation in LPS-treated pregnant mice.

Lipopolysaccharide (LPS), produced by gram-negative bacteria, mediates vasodilatation, changing the action of contractile smooth muscle by increasing expression of nitric oxide synthase and prostaglandin. For the first time we demonstrate, by immunohistochemical methods, that administration of LPS to pregnant mice causes alpha-actin-mediated down-regulation of contractile filaments in uterine blood vessels, thereby potentially increasing vessels permeability, blood supply, and immune cells homing to this environment, culminating in the reestablishment of uterine homeostasis.