Lysophosphatidic acid stimulates astrocyte proliferation through LPA1

Lysophosphatidic acid (LPA) is an extracellular lipid mediator that regulates nervous system development and functions through multiple types of LPA receptors. Here we explore the role of LPA receptor subtypes in cortical astrocyte functions. Astrocytes cultured under serum-free conditions were found to express the genes of five LPA receptor subtypes, lpa(1) to lpa(5). When astrocytes were treated with dibutyryl cyclic adenosine monophosphate, a reagent inducing astrocyte differentiation or activation, lpa(1) expression levels remained unchanged, but those of other LPA receptor subtypes were relatively reduced. LPA stimulated DNA synthesis in both undifferentiated and differentiated astrocytes, but failed to do so in astrocytes prepared from mice lacking lpa(1) gene. LPA also inhibited [H-3]-glutamate uptake in both undifferentiated and differentiated astrocytes; and LPA-induced inhibition of glutamate uptake was still observed in lpa(1)-deficient astrocytes. Taken together, these observations demonstrate that LPA(1) mediates LPA-induced stimulation of cell proliferation but not inhibition of glutamate uptake in astrocytes. (C) 2007 Elsevier Ltd. All rights reserved.