Activation of CysLT receptors induces astrocyte proliferation and death after oxygen-glucose deprivation.
We recently found that 5-lipoxygenase (5-LOX) is activated to produce cysteinyl leukotrienes (CysLTs), and CysLTs may cause neuronal injury and astrocytosis through activation of CysLT(1) and CysLT(2) receptors in the brain after focal cerebral ischemia. However, the property of astrocyte responses to in vitro ischemic injury is not clear; whether 5-LOX, CysLTs, and their receptors are also involved in the responses of ischemic astrocytes remains unknown. In the present study, we performed oxygen-glucose deprivation (OGD) followed by recovery to induce ischemic-like injury in the cultured rat astrocytes. We found that 1-h OGD did not injure astrocytes (sub-lethal OGD) but induced astrocyte proliferation 48 and 72 h after recovery; whereas 4-h OGD moderately injured the cells (moderate OGD) and led to death 24-72 h after recovery. Inhibition of phospholipase A(2) and 5-LOX attenuated both the proliferation and death. Sub-lethal and moderate OGD enhanced the production of CysLTs that was inhibited by 5-LOX inhibitors. Sub-lethal OGD increased the expressions of CysLT(1) receptor mRNA and protein, while moderate OGD induced the expression of CysLT(2) receptor mRNA. Exogenously applied leukotriene D(4) (LTD(4)) induced astrocyte proliferation at 1-10 nM and astrocyte death at 100-1,000 nM. The CysLT(1) receptor antagonist montelukast attenuated astrocyte proliferation, the CysLT(2) receptor antagonist BAY cysLT2 reversed astrocyte death, and the dual CysLT receptor antagonist BAY u9773 exhibited both effects. In addition, LTD(4) (100 nM) increased the expression of CysLT(2) receptor mRNA. Thus, in vitro ischemia activates astrocyte 5-LOX to produce CysLTs, and CysLTs result in CysLT(1) receptor-mediated proliferation and CysLT(2) receptor-mediated death.
Huang
Xiao-Jia
XJ
Department of Pharmacology, School of Medicine, Zhejiang University, Hangzhou 310058, People's Republic of China.
Zhang
Wei-Ping
WP
Li
Cheng-Tan
CT
Shi
Wen-Zhen
WZ
Fang
San-Hua
SH
Lu
Yun-Bi
YB
Chen
Zhong
Z
Wei
Er-Qing
EQ
D000818:Animals; D000831:Animals, Newborn; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism; D001253:Astrocytes / Q000187:drug effects* / Q000201:enzymology; D015153:Blotting, Western; D002452:Cell Count; D016923:Cell Death / Q000187:drug effects; D015687:Cell Hypoxia / Q000502:physiology*; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D005947:Glucose / Q000172:deficiency*; D007150:Immunohistochemistry; D017998:Leukotriene D4 / Q000494:pharmacology; D008565:Membrane Proteins / Q000187:drug effects / Q000502:physiology; D051381:Rats; D018077:Receptors, Leukotriene / Q000819:agonists* / Q000187:drug effects / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction
D008565:Membrane Proteins; D018077:Receptors, Leukotriene; D017998:Leukotriene D4; C412375:cysteinyl leukotriene receptor 2; D001094:Arachidonate 5-Lipoxygenase; D005947:Glucose; C083169:leukotriene D4 receptor