| Neural stem cells (NSCs) are operationally defined as mitotically competent, self-renewing, and multipotent cells able to differentiate along three main cell lineages in the early neurogenesis (i.e., neurons, astrocytes, and oligodendrocytes). Since the identification of NSCs, their unique properties have made NSCs an attractive subject for therapeutic applications to the damaged brain. The elucidation of external signals that might be involved in the regulation of NSCs in respect of their proliferation and differentiation may develop a replenishable source of replacement cells and thus allow for improving transplantation methods and augmenting the treatment of neurodegenerative disorders.Lysophosphatidic acid is a simple and natural phospholipid. It is the component of serum and present in the brain at relatively high levels compared to other tissues. LPA receptors, LPAI-AS, express in many types of cells. In fact, LPA produces responses in abroad range of cell types including neurons, neuroglia and so on. LPA-induced cell type-specific effects include changes in cell morphology, promotion of cell proliferation and cell survival, induction of cell death, changes in ion conductance and Ca2+ mobilization and so on. Contoset al. have reported that LPA increases proliferation of cultured neuroblasts dissected from cerebral cortices of E12-13 mice. For there appeared no detailed report concerning the possible effects of LPA on NSCs, the part I of the present study was aimed to examine the possible roles of LPA in proliferation of embryonic NSCs of rats in vitro and tentative analyse the specific receptors involved and also the signal transduction pathways as well. Based on the promotive action of LPA on proliferation of NSCs, in part II we observed the effect of LPA on neurons, especially cholinergic neurons; and at the same time we also observed the effect of LPA on cells migration. In part III we observed the effect of LPA on the serum-induced differentiation of neuroglia.Part I Promotive action of LPA on proliferation of embryonic NSCs and tentative analysis of related signaling pathways in ratsIn this study, by using neurosphere-counting and [3H] thymidine incorporation techniques, LPA was shown to exhibit a dual or bi-directional action on the proliferation of rat embryonic NSCs in vitro according to the concentrations of LPA used: the lower concentrations of LPA (<1.0 umol/L) showed a dose-dependent increase of the number of NSCs, and it peaked atconcentration of 1.0 umol/L with an increase rate up to 1.69?.15 fold (P<0.01), while as the concentration of LPA reached as higher as than 3.0 umol/L, it began to cause degeneration of NSCs, leading to a dose-dependentreduction of NSCs, as compared to that control cultured with LPA vehicle addition only. For analyzing the possible signaling pathways of LPA-induced promotive action on proliferation of NSCs, NSCs were treated by 1.0 umol/L LPA combined with PTX, an inhibitor of Gi protein activation and the data showed that most of the LPA-induced proliferation was blocked by PTX application either by neurosphere-counting method (decreased by 98%) or by [3H] thymidine incorporation technique (decreased by 89%). Finally, by RT-PCR assays, out of three subtypes of LPA receptors tested, L?AI and LPA3 were markedly expressed while LP/vj was found to be faintly expressed by rat embryonic NSCs as examined at 20 DIV. These results suggest that LPA exhibits dual action on the proliferation of NSCs and its promotive effect might be brought about mainly by acting on LPAi and LPA3 receptors that almost completely coupled to the pertussis toxin-sensitive Gi-Ras-Raf-MAPK pathway other than the pertussis toxin-insensitive ones.Part II Promotive action of LPA on differentiation of MAPI-positive and ChAT-positive neurons and cells migration from rat embryonic NSCs in vitroTo study the effects of LPA on the neuronal differentiation from NSCs, we detected the MAP2-positive (microtubule-associated protein-2, general marker of neurons) and ChAT-positive (choline acetyltranf...
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