Time-dependent mitochondrial-mediated programmed neuronal cell death prolongs survival in sepsis.
OBJECTIVE
To investigate whether apoptosis is a possible mechanism of brain dysfunction occurring in septic syndrome.


METHODS
Experimental prospective study.


METHODS
Laboratory of Surgical Research at the University of Athens.


METHODS
Male pathogen-free Wistar rats.


METHODS
Rats (n = 112) were subjected to sepsis by cecal ligation and puncture. Sham-operated animals (n = 40) underwent the same procedure but without ligation or puncture. Septic animals were either randomly divided (n = 62) in six groups and studied at 6, 12, 24, 36, 48, and 60 hrs after the operation or monitored (n = 50) for 48 hrs as a survival study group. Sham-operated animals were killed at 6, 12, 24, 36, 48, and 60 hrs after the procedure. Brain and cecum were then removed and postfixed in paraffin sections. Apoptosis was evaluated by light microscopy in hematoxylin and eosin-stained specimens and by transmission electron microscopy. In paraffin-embedded sections, immunostaining for bax, bcl-2, cytochrome c, and caspase-8 was done.


RESULTS
In septic rats, increased apoptosis was detected in neurons of the CA1 region of the hippocampus, in choroid plexus, and in Purkinje cells of the cerebellum. Bax immunopositivity was found decreased after the septic insult (p =.03). Bax immunoreactivity was altered as the septic syndrome evolved; it was up-regulated in the early stages (6-12 hrs) and progressively decreased in the late phases (p =.001). Cytochrome c presented a similar regional pattern of expression and was found to be the sole gene marker carrying an independent prognostic role (p =.03). Both bcl-2 and caspase-8 expression remained at constant levels at all times evaluated.


CONCLUSIONS
There is evidence that more neurons undergo apoptosis during sepsis than in normal brain tissue in certain sites where the blood-brain barrier is compromised. In this phenomenon, mitochondrial gene regulators such as bax and products such as cytochrome c seem to play important regulating and prognostic roles, respectively.
Laboratory of Surgical Research, First Department of Propaedeutic Surgery, Athens Medical School, Hippokration Hospital, Athens, Greece.
Evangelos
E
Messaris
Nicholas
N
Memos
Emmy
E
Chatzigianni
Manousos M
MM
Konstadoulakis
Evangelos
E
Menenakos
Stylianos
S
Katsaragakis
Constatine
C
Voumvourakis
George
G
Androulakis
D000818:Animals; D017209:Apoptosis / Q000235:genetics; D053181:Caspase 8; D020169:Caspases / Q000032:analysis; D002432:Cecum / Q000473:pathology; D002831:Choroid Plexus / Q000473:pathology*; D045304:Cytochromes c / Q000032:analysis; D003593:Cytoplasm / Q000737:chemistry / Q000648:ultrastructure; D004195:Disease Models, Animal; D019254:Genes, bcl-2; D006624:Hippocampus / Q000473:pathology*; D008297:Male; D008928:Mitochondria / Q000648:ultrastructure; D009474:Neurons / Q000737:chemistry / Q000648:ultrastructure*; D011379:Prognosis; D011518:Proto-Oncogene Proteins / Q000032:analysis; D019253:Proto-Oncogene Proteins c-bcl-2; D011689:Purkinje Cells / Q000648:ultrastructure*; D051381:Rats; D017208:Rats, Wistar; D018805:Sepsis / Q000201:enzymology / Q000473:pathology*; D016019:Survival Analysis; D013997:Time Factors; D051028:bcl-2-Associated X Protein
C494828:Bax protein, rat; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c; C505528:Casp8 protein, rat; D053181:Caspase 8; D020169:Caspases