Expression of apoptosis regulatory factors during myocardial dysfunction in endotoxemic rats.
OBJECTIVE
To document the time course of apoptosis pathway activation in sepsis and to determine whether Bcl-2 overexpression would improve endotoxin-induced myocardial dysfunction and mortality rate.


METHODS
Randomized, controlled trial.


METHODS
Experimental laboratory.


METHODS
Male Sprague Dawley rats, wild-type C57BL/6 female mice, C57BL/6 female mice overexpressing Bcl-2.


METHODS
Hearts were isolated from rats treated with endotoxin (10 mg/kg, intravenously) to perform heart function, immunohistochemistry (terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick 3'-end labeling, caspase 3), RNase protection assay, reverse transcriptase polymerase chain reaction, Western blotting (caspase 3), and radiolabeled annexin V studies. Twenty-four hours before endotoxin challenge (10 mg/kg, intravenously), rats were pretreated with saline or endotoxin (0.5 mg/kg, intraperitoneally), with or without parthenolide (1 mg/kg, intraperitoneally). Isolated hearts were used to test myocardial function. Mortality induced by endotoxin (10 mg/kg, intraperitoneally) was tested on wild-type or mice overexpressing Bcl-2.


RESULTS
Endotoxin-induced heart dysfunction was maximal at 4 and 8 hrs postinjection, started to improve, and was fully restored at 24 hrs after endotoxin treatment. Endotoxin also induced phosphatidylserine outer leaflet membrane exposure, caspase 3 activation, nuclear apoptosis, and changes in apoptosis gene expression. Bcl-2 overexpression induced by endotoxin pretreatment prevented endotoxin-induced myocardial dysfunction. Mice overexpressing Bcl-2 had dramatic improvement in survival rate compared with wild-type mice.


CONCLUSIONS
These observations suggest that both death receptor and caspase-mediated apoptosis processes are activated in this sepsis model. Bcl-2 overexpression before endotoxin challenge prevents myocardial dysfunction in rats and improves survival rate in mice.
Lancel
Steve
S
Département de Physiologie, Faculté de Médecine, Université de Lille 2, Lille, France.
Petillot
Patrice
P
Favory
Raphael
R
Stebach
Nicolas
N
Lahorte
Christophe
C
Danze
Pierre Marie
PM
Vallet
Benoît
B
Marchetti
Philippe
P
Neviere
Remi
R
D000818:Animals; D017209:Apoptosis; D009202:Cardiomyopathies / Q000503:physiopathology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D004731:Endotoxins; D005260:Female; D015870:Gene Expression; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009206:Myocardium / Q000166:cytology / Q000473:pathology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D018805:Sepsis / Q000235:genetics / Q000401:mortality / Q000503:physiopathology*; D016019:Survival Analysis
D004731:Endotoxins; D019253:Proto-Oncogene Proteins c-bcl-2; C505409:Casp3 protein, mouse; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases