Lysophospholipids trigger calcium signals but not DNA synthesis in cortical astrocytes

Astrocytes generate calcium signals and proliferate in response to a growth factor-like lipid bound to plasma and serum albumin, in a process likely t o be important in the formation of glial scars, A number of potential candi dates for the physiologically active lipid were investigated. Lysophosphati dic acid, lysophosphatidylcholine, sphingomyelin, and platelet-activating f actor all elicited calcium signals of varying magnitudes in cortical astroc ytes, although only lysophosphatidic acid elicited calcium signals comparab le in amplitude to those induced by the active physiological lipid. None of these lipids, however, caused cell division in astrocytes. There is theref ore no invariable relationship between the ability of lipids to induce calc ium signals and mitogenic activity. None of the lipids investigated demonst rate the activity of the natural lipid factor in generating both calcium si gnals and mitotic activity in astrocytes. (C) 1999 Wiley-Liss, Inc.