[The changes of inducible nitric oxide synthase activity and apoptosis-related gene expression in endotoxemia-induced rat diaphragm].
OBJECTIVE
To study the changes of inducible nitric oxide synthase (iNOS) activity and apoptosis-related genes Bcl-2, Bax and caspase-3 mRNA expressions in endotoxemia-induced rat diaphragm injury and analyze the related apoptosis mechanism.


METHODS
Thirty-two male SD rats were randomly divided into 4 groups (n = 8): control group (saline 0.5 ml ip), endotoxin 24 h, 48 h and 96 h group (endotoxin 12 mg/kg ip, animals were killed either 24, 48 or 96 h after injections). Body weight were measured, the ratio between diaphragm weight and body weight, activities of constitutive nitric oxide syntheses (cNOS), iNOS and succinate dehydrogenase (SDH) were also measured. The expressions of Bcl-2, Bax and caspase-3 mRNA were detected by RT-PCR analysis.


RESULTS
Endotoxin induced significant reductions in diaphragm mass in endotoxin 96 h group (P < 0.05). Endotoxin increased diaphragm cNOS or iNOS activities, and they were significantly higher in endotoxin 96 h group than those in endotoxin 24 h and 48 h groups, diaphragm SDH activity was reduced, and it was lower in endotoxin 96 h group than that in endotoxin 24 h and 48 h groups (P < 0.01). Endotoxin significantly increased Bax and caspase-3 mRNA expressions, and they were higher in endotoxin 48 h and 96 h groups than those in endotoxin 24 h group (P < 0.01). Endotoxin significantly reduced Bcl-2 mRNA expression and the ratio of Bcl-2/Bax, and they were lower in endotoxin 48 h and 96 h groups than those in endotoxin 24 h group (P < 0.01).


CONCLUSIONS
iNOS is activated in endotoxemia-induced rat diaphragm injury. It damages mitochondria, upregulates Bax expression and downregulates Bcl-2 expression, then induces caspase-3 related apoptotic pathway. These changes may cause diaphragm injury and atrophy.
Department of Physiology, Bengbu Medical College, Bengbu 233030, China.
Ying-Yan
YY
Fang
Su-Dong
SD
Guan
Xiao-Lei
XL
Guo
Hong-Wei
HW
Ye
Hua-Xue
HX
Wang
Qin
Q
Gao
D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D003964:Diaphragm / Q000378:metabolism* / Q000503:physiopathology; D019446:Endotoxemia / Q000378:metabolism*; D015870:Gene Expression; D008297:Male; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D051028:bcl-2-Associated X Protein / Q000378:metabolism
C494828:Bax protein, rat; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; C505410:Casp3 protein, rat; D053148:Caspase 3