Ependymal epithelium disruption after vanadium pentoxide inhalation. A mice experimental model.

The blood-brain barrier (BBB) protects the CNS against chemical insults. Regulation of blood-brain tissue exchange is accomplished by ependymal cells, which possess intercellular tight junctions. Loss of BBB function is an etiologic component of many neurological disorders. Vanadium (V) is a metalloid widely distributed in the environment and exerts potent toxic effects on a wide variety of biological systems. The current study examines the effects of Vanadium pentoxide (V2O5) inhalation in mice ependymal epithelium, through the analysis of the brain metal concentrations and the morphological modifications in the ependymal cells identified by scanning and transmission electron microscopy after 8 weeks of inhalation, in order to obtain a possible explanation about the mechanisms that V uses to enter and alter the CNS. Our results showed that V2O5 concentrations increase from the first week of study, stabilizing its values during the rest of the experiment. The morphological effects included cilia loss, cell sloughing and ependymal cell layer detachment. This damage can allow toxicants to modify the permeability of the epithelium and promote access of inflammatory mediators to the underlying neuronal tissue causing injury and neuronal death. Thus, understanding the mechanisms of BBB disruption would allow planning strategies to protect the brain from toxicants such as metals, which have increased in the atmosphere during the last decades and constitute an important health problem.

Inhalation of cadmium, lead or its mixture Effects on the bronchiolar structure and its relation with metal tissue concentrations.

The human population in the industrialized world is constantly exposed to chemical mixtures of pollutants such as metals; information about the consequences of the interactions of these compounds on health is scarce. The current study examines the effects of the inhalation of lead (Pb), cadmium (Cd) and Pb-Cd mixture in mice models analyzing the metal concentrations in lung, and the morphological modifications in the bronchiolar epithelium identified by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) after 4 weeks of inhalation. Our results showed that metal concentrations in lung were higher compared to controls; however, Pb concentrations drastically decrease with the mixture. This reduction was also observed in the inhalation chamber. These data correlate with the morphological alterations observed, which consisted of flattened and decreased number of nonciliated bronchiolar cells (NCBC), bald ciliated cells and bundles of NCBC. These modifications were mainly given by Cd, alone or in combination with Pb. The clusters formed by NCBC cells suggest cell proliferation which probably means that after metal inhalation, the cells enhance their proliferative capacity in order to repopulate the bronchiolar wall.