No abstract

Brain-derived neurotrophic factor (BDNF) is a principal factor for neurogenesis, neurodevelopment and neural survival through a BDNF receptor, tropomyosin-related kinase (Trk) B, while BDNF can also cause a decrease in the intracellular glutathione (GSH) level. We investigated the exacerbation of methylmercury-induced death of rat cerebellar granular neurons (CGNs) by BDNF in vitro. Since methylmercury can decrease intracellular GSH levels, we hypothesized that a further decrease of the intracellular GSH level is involved in the process of the exacerbation of neuronal cell death. In the present study, we established that in CGN culture, a decrease of the intracellular GSH level was further potentiated with BDNF in the process of the methylmercury-induced neuronal death and also in GSH reducer-induced neuronal death. BDNF treatment promoted the decrease in GSH levels induced by methylmercury and also by L-buthionine sulfoximine (BSO) and diethyl maleate (DEM). The promoting effect of BDNF was observed in a TrkB-vector transformant of the rat neuroblastoma B35 cell line but not in the mock-vector transformant. These results indicate that the exacerbating effect of BDNF on methylmercury-induced neuronal death in cultures of CGNs includes a further decrease of intracellular GSH levels, for which TrkB is essential.

ABSTRACT. Hepatic stellate cells (HSCs) intracellularly preserve vitamin A in the normal liver. When the liver is damaged, HSCs transform into myofibroblast-like cells, and then proliferate and increase their expression of collagen. Cultured on a plastic plate, HSCs spontaneously activate. To maintain HSCs in a quiescent state with low expression of collagen, coating methods with extracellular matrixes (ECMs) such as Matrigel-coating or laminin-rich coating are commonly used for HSC cultivation. Kishimoto et al. [14] reported that Fragmin ® /protamine microparticles (F/P-MPs) have the ability to absorb heparin-binding cytokines like ECMs. Therefore, we examined whether the cultivation on an F/P-MPs-coated plate maintains the quiescent state of RI-T cells (derived from rat HSCs) including the suppression of collagen expression. We found that the mRNA levels of collagen type IαI and TGF-β1 in RI-T cells were significantly suppressed in the cultivation on F/P-MPs-coated plates compared to cultures on noncoated and Matrigel-coated plates. We conclude that the F/P-MPs coating method is useful for maintaining with low expressions of collagen IαI and TGF-β 1 mRNA levels in HSCs. KEY WORDS: collagen type IαI, Fragmin/protamine microparticles, hepatic stellate cell, TGF-β1.

No abstract