Transport of Human Lactoferrin into Mouse Brain: Administration Routes and Distribution

We studied different ways of transport of human lactoferrin to the brain of C57Bl/6 mice after its administration via different routes, analyzed its distribution in the brain, and determined the phenotype of lactoferrin-containing cells. Colocalization of lactoferrin and markers of various cell types was estimated by fluorescent immunohistochemical analysis. Lactoferrin was detected in mouse brain sections after its intranasal, sublingual, and intraperitoneal administration, but not after conjunctival administration. After intranasal administration, lactoferrin rapidly penetrated into the brain and accumulated in the cytoplasm of vascular endothelial cells in the neocortex, striatum, hippocampus, and thalamus. After application of protein solution onto fixed floating sections, highly specific binding of lactoferrin was found in the nuclei of neurons, astrocytes, and microglia cells, but not in the nuclei of endothelial cells of mouse brain.