Possible involvement of NO/NOS signaling in hippocampal amyloid-beta production induced by transient focal cerebral ischemia in aged rats.
In the present study, to define the roles of nitric oxide (NO) signaling in amyloid-beta (A beta) production after transient cerebral ischemia, extracellular levels of NO and A beta were monitored by intracerebral microdialysis in the hippocampus of aged rats exposed to transient middle cerebral artery occlusion and reperfusion (MCAO/R). The results indicated that 1-h MCAO significantly upregulated hippocampal NO and A beta levels. In addition, the NO elevation preceded the A beta changes. The Western blotting suggested that acute hypoperfusion could increase the expression of beta-secretase 1 (BACE1) but not BACE2. The enhanced NO concentration in acute stage of MCAO/R was coincident with increased eNOS expression, while in subacute stage was coincident with increased iNOS and nNOS. Our results also indicated that pretreatment of L-NAME, one non-selective NOS inhibitor could decrease the BACE1 expression, reverse both NO and A beta changes and rescue the delayed neuronal death. These preliminary findings indicated that activation of NOS/NO signaling system could trigger A beta production through BACE1 pathway during acute ischemic episode. The present data may be important in understanding, at least in part, the pathological role of NO/NOS system involved in hippocampal A beta production and neuronal damage induced by transient cerebral ischemia.
Li
Song
S
Institute of Neuroinformatics, Dalian University of Technology, 116024 Dalian, China. lisong_spu2005@yahoo.com
Wang
Wei
W
Wang
Che
C
Tang
Yi-Yuan
YY
D000208:Acute Disease; D000375:Aging; D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000503:physiopathology*; D020244:Infarction, Middle Cerebral Artery / Q000188:drug therapy / Q000503:physiopathology*; D002546:Ischemic Attack, Transient / Q000188:drug therapy / Q000503:physiopathology*; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000008:administration & dosage / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors
D016229:Amyloid beta-Peptides; D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases; C509287:Bace2 protein, rat; C509281:Bace1 protein, rat; D019331:NG-Nitroarginine Methyl Ester