title: Time-course alterations of Toll-like receptor 4 and NF-κB p65, and their co-expression in the gerbil hippocampal CA1 region after transient cerebral ischemia.
abstract: Innate immune system is very important to modulate the host defense against a large variety of pathogens. Toll-like receptors (TLRs) play a key role in controlling innate immune response. Among TLRs, TLR4 is a specific receptor for lipopolysaccharide and associated with the release of pro-inflammatory cytokines. In the present study, we investigated ischemia-related changes of TLR4 immunoreactivity and its protein level, and nuclear factor κB (NF-κB) p65 immunoreactivity regarding inflammatory responses in the hippocampal CA1 region after 5 min of transient cerebral ischemia to identify the correlation between transient ischemia and inflammation. In the sham-operated group, TLR4 immunoreactivity was easily detected in pyramidal neurons of the hippocampal CA1 region (CA1). TLR4 immunoreactivity in pyramidal neurons was distinctively decreased after ischemia/reperfusion (I/R); instead, based on double immunofluorescence study, TLR4 immunoreactivity was expressed in non-pyramidal neurons and astrocytes from 2 days postischemia. In addition, TLR4 protein level was lowest at 1 day postischemia and highest 4 days after I/R. On the other hand, NF-κB p65 immunoreactivity was not detected in the CA1 of the sham-operated group, and NF-κB p65 immunoreactivity was not observed until 1 day after I/R. However, NF-κB p65 immunoreactivity began to be expressed in astrocytes at 2 days postischemia, and the immunoreactivity was strong 4 days postischemia. Our results indicate that TLR4 and NF-κB p65 immunoreactivity are changed in CA1 pyramidal neurons and newly expressed in astrocytes, not in microglia, in the CA1 region after transient cerebral ischemia.
authors.affiliation: Department of Oral Anatomy, College of Dentistry, Gangneung-Wonju National University, Gangneung 210-702, South Korea.
authors.forename: Ki-Yeon
authors.initials: KY
authors.lastname: Yoo
authors.forename: Dae Young
authors.initials: DY
authors.lastname: Yoo
authors.forename: In Koo
authors.initials: IK
authors.lastname: Hwang
authors.forename: Joon Ha
authors.initials: JH
authors.lastname: Park
authors.forename: Choong Hyun
authors.initials: CH
authors.lastname: Lee
authors.forename: Jung Hoon
authors.initials: JH
authors.lastname: Choi
authors.forename: Seung-Hae
authors.initials: SH
authors.lastname: Kwon
authors.forename: Song
authors.initials: S
authors.lastname: Her
authors.forename: Yun Lyul
authors.initials: YL
authors.lastname: Lee
authors.forename: Moo-Ho
authors.initials: MH
authors.lastname: Won
mesh_terms: D000818:Animals; D056547:CA1 Region, Hippocampal / Q000378:metabolism* / Q000473:pathology; D016923:Cell Death; D005849:Gerbillinae; D007113:Immunity, Innate / Q000502:physiology; D002546:Ischemic Attack, Transient / Q000473:pathology / Q000503:physiopathology*; D009474:Neurons / Q000473:pathology; D051197:Toll-Like Receptor 4 / Q000096:biosynthesis*; D051996:Transcription Factor RelA / Q000096:biosynthesis*
chemical_list: D051197:Toll-Like Receptor 4; D051996:Transcription Factor RelA