The time-dependent effect of lipopolysaccharide on kainic acid-induced neuronal death in hippocampal CA3 region: possible involvement of cytokines via glucocorticoid.
It has been reported that glucocorticoid (Gc) can induce neuronal cell toxicity in the hippocampus. In addition, we examined that serum Gc increased by restraint stress aggravated kainic acid (KA)-induced neuronal death in hippocampal CA3 region. However, the effect of other stressful stimulus like lipopolysaccharide (LPS) increasing serum Gc on KA-induced neuronal death was not elucidated until now. Thus, we examined the time course effect of LPS on KA-induced neuronal death in the hippocampal CA3 region of mice, especially to address the role of Gc and inflammatory mediators. In the present study, we found that an aggravating effect of LPS on KA-induced neuronal death was correlated with an alteration of hippocampal IL-1beta mRNA level at all time points, and the serum Gc and hippocampal IL-1beta mRNA level was peak at 90 min after LPS treatment (LPS 90 min) when the aggravating effect of LPS on KA-induced neuronal death was maximum. In addition, RU38486 (glucocorticoid receptor antagonist) decreased the hippocampal IL-1beta mRNA level and abolished the aggravating effect of LPS on KA-induced neuronal death at LPS 90 min and 24 h. In the immunohistochemical study, we found activated and ramified microglia (OX-42) and astrocyte (GFAP) at 24 h after LPS treatment (LPS 24 h) in the hippocampus. These results suggest that Gc itself, cytokines triggered by Gc, or both appears to be involved in the LPS effect depending on LPS pretreatment time.
Kwon
M-S
MS
Department of Aerospace Medical Research, Aerospace Medical Center, Republic of Korea Air Force (ROKAF), Chungcheongbuk-Do, South Korea.
Seo
Y-J
YJ
Choi
S-M
SM
Won
M-H
MH
Lee
J-K
JK
Park
S-H
SH
Jung
J-S
JS
Sim
Y-B
YB
Suh
H-W
HW
D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000502:physiology; D056654:CA3 Region, Hippocampal / Q000187:drug effects* / Q000503:physiopathology; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D003345:Corticosterone / Q000097:blood / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D018690:Excitatory Amino Acid Agonists / Q000633:toxicity*; D053583:Interleukin-1beta / Q000378:metabolism; D007608:Kainic Acid / Q000633:toxicity*; D008070:Lipopolysaccharides / Q000633:toxicity*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D017628:Microglia / Q000187:drug effects / Q000502:physiology; D015735:Mifepristone / Q000494:pharmacology; D015213:Neuroimmunomodulation / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000037:antagonists & inhibitors / Q000378:metabolism; D013997:Time Factors
D016207:Cytokines; D018690:Excitatory Amino Acid Agonists; D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid; D015735:Mifepristone; D007608:Kainic Acid; D003345:Corticosterone