Einfluss der Anästhetika Sevofluran und Propofol auf den nekrotischen und den apoptotischen Zelltod nach inkompletter zerebraler Hemisphärenischämie und Reperfusion in der Ratte über einen Beobachtungszeitraum von 28 Tagen

The long-term effect of sevoflurane and propofol on necrotic and
apoptotic cell death after incomplete cerebral ischemia and
reperfusion in the rat The present study investigates the effect of
the anesthetic agents propofol and sevoflurane on irreversible cell
damage (necrosis) and programmed cell death (apoptosis) for a time
period of 28 days after incomplete transient cerebral ischemia and
reperfusion in the rat. Ninety-six fasted male Sprague-Dawley rats
(415±40g) were anesthetized, intubated and ventilated with 2 Vol%
isoflurane and N2O/O2 (FiO2=0.33). Catheters were inserted into the
right femoral artery and vein as well as in the right jugular vein
for drug administration and blood withdrawal. At the end of surgery
animals were randomly assigned to one of the following groups:
control (n=32): 25 µg/kg/h fentanyl i.v. and N2O/O2 (FiO2=0.33);
propofol (n=32): 25 µg/kg/h propofol i.v. and O2/air (FiO2=0.33);
sevoflurane (n=32) 2 Vol% sevoflurane in O2/air (FiO2=0.33).
Ischemia (45min) was produced by unilateral common carotid artery
occlusion plus hemorrhagic hypotension (MAP=40 mmHg). Pericranial
temperature (37.5°C), arterial blood gases and pH were maintained
constant. Animals were then randomly assigned to a postischemic
reperfusion time of 01, 03, 07, or 28 days. At the end of the
observation period the animals were deeply anesthetized and killed,
the brains were removed, frozen at –70 °C, and sectioned for
further evaluation. Hematoxylin-Eosin staining was used to evaluate
eosinophilic cell damage and tissue damage in 7 μm sections in the
hippocampus, dentate gyrus and surrounding tissues.
Immunohistochemistry was used to detect activated caspase-3 as a
marker of apoptotic cell death. To distinguish activated
caspase-3-positive neurons from other cells, a double staining,
using the specific neuronal marker NeuN was used additionally. The
results showed that with the exception of one animal in the
sevoflurane group there is no tissue damage or eosinophilic cell
damage in either the propofol or the sevoflurane treated animals up
to 28 days after ischemia. The only eosinophilic tissue damage was
present in the control group. About one percent of the hippocampal
neurons of all three groups were activated caspase-3-positive,
independently of the observation period. Though there was a
tendency in both treatment groups to a lower number of activated
caspase-3-positive cells. Results of the double staining showed
that activated caspase-3, though mainly expressed in neurons, is
also expressed in other cells. The present study showed that
propofol and sevoflurane both produce a sustained inhibition of
eosinophilic cell damage up to 28 days after incomplete cerebral
ischemia in rats. Although the amount of activated
caspase-3-positive neurons was similar in the three groups there
was a tendency towards a lower number in the treatment groups
compared to control. This suggests that neuroprotection seen with
both, propofol and sevoflurane, involves anti-necrotic mechanisms
rather than anti-apoptotic mechanisms. Further investigations will
be required in the future to investigate the detailed mechanisms of
propofol and sevoflurane to develop a successful treatment of
ischemic insults and their consequences.