Fumonisin B1 induces necrotic cell death in BV-2 cells and murine cultured astrocytes and is antiproliferative in BV-2 cells while N2A cells and primary cortical neurons are resistant

Fumonisin B-1 (FB1), a mycotoxin produced by Fusarium verticillioides, causes equine leukoencephalomalacia, impairs myelination, and inhibits neuronal growth in vitro. Intact mice do not show brain damage after systemic administration of FBI. We recently reported that intracerebroventricular administration of FBI in mice caused neurodegeneration in the cortex and activation of astrocytes in the hippocampal area; results suggested that the neuronal damage may be secondary, to activation of immunocompetent non-neuronal cells. Current study investigated effects of FB1 upon murine inicroglial (BV-2) and neuroblastoma (N2A) cell lines, and primary astrocytes and cortical neurons. BV-2 and N2A cultures and cells prepared from neonatal and postnatal brains of BALB/c mice were exposed to various concentrations of FBI for 4 (BV-2 and N2A) or 4 and 8 (astrocytes and cortical neurons) days. FBI at 25 P M decreased viability in BV-2 cells, whereas at 50 mu M caused necrotic but not apoptotic cell death in both BV-2 and primary astrocytes (at day 8 only), assessed by lactic dehydrogenase release, and pripidium iodide and annexin V staining. Thymidine incorporation indicated that 2.5 mu M FBI decreased proliferation in BV-2 cells. DNA analysis by flow cytometry showed that the inhibition was not caused by cell cycle arrest. The mitochondrial activity decreased dose-dependently in BV-2 cells and was significantly elevated at 25 mu M FBI, but not at 50 mu M at days 4 or 8 in astrocytes. In BV-2 cells and primary astrocytes, the expression of TNF alpha and IL-1 beta analyzed by real-time polymerase chain reaction was downregulated at 6 or 24 h. In all cell types tested the FB1 treatment caused accumulation of free sphinganine and decrease in free sphingosine levels at selected time points. Results indicated that primary and established marine brain immunocompetent cells are vulnerable to the FBI-dependent cytotoxicity in vitro whereas neuronal cells are not. The toxic effects at? the neuronal tissue may therefore be secondary to modulation of astrocyte or glial cell function. (c) 2005 Elsevier Inc. All rights reserved.