Cells damage observed in neural tissue following exposure to ET (Table 3) can be sorted into two categories: i) cellular swelling with microvacuolation, and ii) presence of hyperchromatic

cells, also called dark cells, (possibly being post-mortem histological neuronal artefacts resulting from brain manipulation, Jortner, 2006), and shrunken cells with nuclear pyknosis. Tissular localization and severity of cells damage depend on ET doses, on the delay between ET injection and animal sacrifice (Finnie, 1984a, 1984b; Finnie et al., 1999; Miyamoto et al., Natural Product Library high throughput 2000, 1998) as well as on the repetition of ET injection (Finnie, 1984b; Uzal et al., 2002), but not on the way of its administration (natural disease, intravenous or intraperitoneal injection of ET); see Table 3. Some swelling and pyknotic granule cells have been observed in mouse cerebellum (Finnie, 1984b) but not (or to a lesser extent) in rat cerebellum (Finnie et al., 1999; Miyamoto et al., 1998).

In rat, injection of ET at a sub-lethal dose (50 ng/kg) seems to cause neuronal damage predominantly in the hippocampus (Miyamoto et al., 1998). Overall, this suggests that ET may have different mode of action or different consequences depending to the cells or the animal species. Post-mortem observations of severed neural cells do not allow discriminating between direct and indirect cellular actions of ET. On the one AZD0530 hand, cell alteration in brain tissue may be an indirect consequence of vasogenic oedema: reduction of parenchyma perfusion leads to hypoxia and cell necrosis. On the other hand, the bilateral symmetry of the damage caused by ET (Table 2, and any sign of Focal Symmetrical Encephalomalacia), notably in the brain stem (Finnie et al., 1999) suggests a nerve-tissue or neural Selleck C59 cells vulnerability to ET. Brain tissue

is comprised of different types of neural cells, including many sub-types of neurons, and glial cells notably astrocytes (velimentous astrocytes, radial glia, etc.) and oligodendrocytes (which are responsible for myelination of certain neuronal axons and therefore contribute to the formation of the cerebral white matter). In the peripheral nervous system, Schwann cells, which are related to oligodendrocytes, ensure myelination of peripheral axons. The observed cellular manifestations (binding, cell damage or death) caused by ET, and the identification of cell types affected by this toxin depend on the actual concentration of ET in the neural tissue. The local concentration of ET is likely depending, in part, on the way by which the toxin is administered. Indeed, during the in vitro studies (i.e. when neural tissue slices or primary cultures are used) concentration of ET is likely to be homogenous while, during the in vivo studies (i.e.