LIPOPOLYSACCHARIDE-INDUCED EXPRESSION OF IP-10 MESSENGER-RNA IN RAT-BRAIN AND IN CULTURED RAT ASTROCYTES AND MICROGLIA

Using mRNA differential display technique, we have found a differentia lly expressed band in rat brain, designated HAP(2)G1, which was the st rongest one induced in response to peripheral administration of lipopo lysaccharide (LPS). Sequence analysis showed that HAP(2)G1 cDNA is the rat homologue of the human alpha-chemokine IP-10. Using RT-PCR techni que and in situ hybridization, we demonstrate that IP-10 mRNA was expr essed only in brain tissue of rats treated with LPS and not in control brain tissue. Using semi-quantitative PCR, we found that both culture d astrocytes and microglia express IP-10 mRNA after treatment with LPS . LPS-induced IP-10 mRNA reached peak levels in rat brain and in cultu red microglia at approximately 3 h after treatment with LPS. At 10 h, IP-10 mRNA was markedly decreased, and at 24 h it was low but still de tectable by PCR or in situ hybridization. In contrast to unstimulated microglia, unstimulated astrocytes constitutively expressed IP-10 mRNA at a low level. Increased IP-10 expression could possibly be involved in the microglia response to inflammatory stimuli in vivo. (C) 1998 E lsevier Science B.V. All rights reserved.