Protective effect of Ginkgolids (A+B) is associated with inhibition of NIK/IKK/IkappaB/NF-kappaB signaling pathway in a rat model of permanent focal cerebral ischemia.
OBJECTIVE
We have previously reported that Ginkgolids which contain Ginkgolids A and B (Ginkgolids (A+B), GKAB) reduce infarct size in a rat model of focal ischemia. NF-kappaB-inducing kinase (NIK)-IkappaBalpha kinase (IKK) pathway plays an important role in activation of nuclear factor kappaB (NF-kappaB). A previous study demonstrated that Ginkgolid B inhibited lipopolysaccharide (LPS)- and platelet activating factor (PAF)-induced NF-kappaB activation in rat pleural polymorphonuclear granulocytes. However, little is known about the inhibitory mechanisms of Ginkgolids on the activation of NF-kappaB. The present study evaluated the effects of GKAB on NIK/IKK/IkappaB/NF-kappaB signaling pathway in a rat model of permanent focal cerebral ischemia.


METHODS
Rats were subjected to permanent middle cerebral artery occlusion (pMCAO) by intraluminal suture blockade. GKAB was injected intravenously (iv) immediately after ischemic onset. Western blot analysis was employed to determine alterations in IkappaBalpha, phosphorylated NIK (p-NIK) and phosphorylated IKKalpha (p-IKKalpha). Immunohistochemistry was used to confirm the nuclear translocation of NF-kappaB p65. RT-PCR was used to detect induction of NF-kappaB target gene c-Myc mRNA.


RESULTS
The results showed a brief increase in p-NIK levels after ischemia. GKAB blocked ischemia-induced increases in p-NIK and p-IKKalpha levels, and reversed the decline in IkappaBalpha levels. Ischemia-induced nuclear translocation of NF-kappaB p65 was attenuated by GKAB(.) GKAB also repressed the ischemia-induced increase in expression of NF-kappaB target gene c-Myc mRNA.


CONCLUSIONS
These findings suggest that GKAB-mediated neuroprotective effect against ischemia appears to be associated with blocking NF-kappaB activation by suppressing the NIK-IKK pathway.
Wang
Xuan
X
Department of Pharmacology and Laboratory of Aging and Nervous Diseases, Soochow University School of Medicine, Suzhou, China.
Qin
Zheng-Hong
ZH
Shi
Hong
H
Savitz
Sean Isaac
SI
Qin
Ai-Ping
AP
Jiang
Yan
Y
Zhang
Hui-Ling
HL
D000818:Animals; D015153:Blotting, Western; D002545:Brain Ischemia / Q000188:drug therapy* / Q000473:pathology / Q000523:psychology*; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D015536:Down-Regulation / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects; D016259:Genes, myc / Q000187:drug effects; D046934:Ginkgolides / Q000494:pharmacology*; D051550:I-kappa B Kinase / Q000037:antagonists & inhibitors; D020672:I-kappa B Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D007150:Immunohistochemistry; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology / Q000523:psychology; D008297:Male; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D018696:Neuroprotective Agents; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects*; D014178:Translocation, Genetic / Q000187:drug effects; D000097782:NF-kappaB-Inducing Kinase
D046934:Ginkgolides; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins; D016328:NF-kappa B; D018696:Neuroprotective Agents; D017346:Protein Serine-Threonine Kinases; D000097782:NF-kappaB-Inducing Kinase