Influence of engineered nanoparticles from metals on the blood-brain barrier permeability, cerebral blood flow, brain edema and neurotoxicity. An experimental study in the rat and mice using biochemical and morphological approaches.

Influence of nanoparticles on brain function following in vivo exposures is not well known. Depending on the magnitude and intensity of nanoparticle exposure from the environment, food and/or water source, neuronal function could be affected and may lead to neurotoxicity and neuropathology. This hypothesis was examined in present investigation using systemic or intracerebroventricular administration of engineered nanoparticles from metals, i.e., Al, Ag and Cu (approximately equal to 50 to 60 nm) on neurotoxicity in rats and mice. Intraperitoneal (50 mg/kg), intravenous (30 mg/kg), intracarotid (2.5 mg/kg) or intracerebroventricular administration (20 microg) of nanoparticles significantly altered the blood-brain barrier (BBB) function to Evans blue and radioiodine in several regions of the brain and spinal cord at 24 h after their administration. Marked decreases in local cerebral blood flow (CBF) and pronounced brain edema was seen in regional areas associated with BBB leakage. Neuronal cell injuries, glial cell activation, heat shock protein (HSP) upregulation and loss of myelinated fibers are quite common in effected brain areas. The observed pathological changes were most pronounced in mice compared to rats. Exposures to Cu and Ag nanoparticles showed most marked effects on brain pathology when administered into systemic circulation or into the brain ventricular spaces as compared to Al nanoparticles. Our results are the first to show that nanoparticles from metals are able to induce selective and specific neurotoxicity that depends on the type of metals, route of administration and the species used.