catalase (ct) activity in placentas complicated with pregnancy

catalase (ct) activity in placentas complicated with pregnancy

6
9
Zoologica
CATALAS
E - ( C T ) -47/3-4:
A C T I V I T69-73
Y-IN-PLACENTAS
Poloniae
(2002)
69
CATALASE (CT) ACTIVITY IN PLACENTAS
COMPLICATED WITH PREGNANCY INDUCED
HYPERTENSION (PIH)
J OLANTA S ACZKO 1 , M A£GORZATA D ACZEWSKA 2 ,
A NNA M ALARSKA 1 E WA S EWERYN 1 , Z BIGNIEW S ACZKO 3 ,
A NTONI O GORZA£EK 4, T ERESA B ANAŒ 1
Wroc³aw Medical University, Department of Medical Biochemistry,
Cha³ubiñskiego 10, 56-368 Wroclaw, Poland
2
Laboratory of Evolutionary and Developmental Biology of Vertebrates, Zoological Institute, University of Wroclaw, Sienkiewicza 21, 50-335 Wroc³aw, Poland
3
Specialized Hospital, Warszawska 2, Wroclaw, Poland
4
Department of General Zoology, Zoological Institute University of Wroc³aw,
Sienkiewicza 21, 50-335 Wroclaw, Poland
1
Abstract. Catalase (CT) activity was investigated in 10 normal placentas and 15
placentas from women with diagnosed pregnancy induced hypertension (PIH). We found
differences in catalase activity between pathological and normal placentas. CT activity
in normal pregnancies remained at a stable level, whereas in PIH placentas CT activity
was lower compared to normal placentas. Single cases of CT increase in pathological
placentas were observed. The results confirm the role of oxidative stress in etiopathogenesis
of pregnancy induced hypertension.
INTRODUCTION
Pathomechanism of pregnancy induced hypertension has not been fully
elucidated. The latest studies suggest an involvement of oxidative stress in the
PIH etiopathogenesis, which is the cause of uncontrolled increase in reactive
oxygen species (ROS) level (H UBEL C. A., 1997; C ANIGGIA et al., 2000). It is
presumed that the pathological focus of this disorder is placenta where much
oxygen is used (M YATT et al., 2000).
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J.-SACZKO-ET-AL.
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In physiological conditions ROS formation is counterbalanced by
antioxidative processes (L UNEC , 1992; K ELLY , 1998). Oxidative stress resulting from the impairment of pro-oxidative-antioxidative homeostasis of organism destabilizes cell and tissue functioning (H ARMAN , 1998). Enzymes specializing in ROS removal, belonging to antioxidative cellular system, are: superoxide dismutase (SOD), catalase (CT), glutathione peroxidase (GPx). Catalase carries out dismutation reaction converting hydrogen peroxide into water
and oxygen molecule (B ARTOSZ , 1995).
The aim of this work was to measure CT in normal and PIH placentas and
to estimate the oxidative stress role in etiopathogenesis of pregnancy induced
hypertension.
MATERIALS AND METHODS
The studies were conducted on 10 normal placentas (pregnancies finished within the 38th-40th week) and on 15 placentas from women with diagnosed pregnancy induced hypertension (pregnancies finished within the 35th 40th week). The placentas were obtained from Specialized Hospital of Gynecology and Obstetrics in Wroc³aw, Poland.
Pregnancy induced hypertension was diagnosed when the value of systolic arterial pressure exceeded 140 mmHg and the mean value of diastolic
pressure reached values above 90 mmHg. These values concerned blood pressure measured after the 20th week of pregnancy. Before pregnancy the women
did not suffer from chronic arterial hypertension, and after delivery blood
pressure returned to normal values without pharmacological aid.
For the experiments segments from the central part of placental discus (2.5 g)
were taken. Immediately after the uptake the cuttings were frozen at -80°C.
To remove red cells, before homogenization the frozen segments were
cleansed in buffer consisting of 0.9% NaOH, 0.5 mM PMSF, 0.5 mM EDTA,
pH 7.4. Homogenization of the placentas was carried out in 10 mM phosphate
buffer, pH 7.4 with 0.5 mM EDTA for 10 minutes. The obtained placentas
homogenates were centrifuged at 750g for 20 minutes. Total protein content
was measured with Bradford method (B RADFORD , 1976).
Catalase activity was measured in the supernatants. The rate of disappearence of H 2O 2 per minute in absorbence at 240 nm was recorded. Enzyme
activity was calculated using molar extinction coefficient of 43.6M.-1. cm -1
for H 2O 2 . The phosphoric buffer pH 7.0 was used.
RESULTS
The placentas coming from normal and pathological pregnancies, were
found to differ in catalase activity. CT activity in normal placentas remained
at a stable level (mean = 29.32 nmol H 2 O 2 x 0.1 x min -1 x mg -1 ). In PIH
placentas CT showed varied activity. In ten pathological placentas (P1, 2, 3,
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CATALASE-(CT)-ACTIVITY-IN-PLACENTAS
71
4, 5, 6, 7, 8, 14, 15) a clear decrease in CT activity was observed in comparison with normal placentas. In placentas P9, 11, 12, 13 increase in CT activity
was found. In placentas P10 and 13 CT the activity was similar to that in
normal placentas (Fig. 1).
35
30
CT activity
25
20
15
10
5
0
N1
N2
N3
N4
N5
N6
N7
N8
N9 N10 P1
P2
P3
P4
P5
P6
P7
P8
P9 P10 P11 P12 P13 P14 P15
number of normal (N) and pathological placentas (P)
Fig. 1. CT activity in normal and pathological placentas.
DISCUSSION
Studies on etiopathogenesis of pregnancy induced hypertension suggest
that an essential factor causing these changes is oxidative stress (M YOTT , 2000;
H UBEL , 1997). The subject of the present investigation was placenta from pregnancies complicated with PIH, because according to the latest studies it is the
main focus of these changes (C UETO , 1997).
In oxidative stress conditions, an uncontrolled increase in reactive oxygen species is observed. This state is followed by lipid peroxidation, enhanced
oxidation of -SH groups as well as an array of other disturbances in cellular
metabolism of placenta, leading to the observed pathological alterations characteristic for PIH (A LEXA , 1996; M ORIKAVA , 1997; G RATACOS , 1999).
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J.-SACZKO-ET-AL.
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Disturbances in oxidative balance induced by oxidative stress could be,
among others, the reflection of a decreased activity of antioxidative enzymes,
where an important part is played by catalase (CT). Catalase is an antioxidative
enzyme localized in cytosol and peroxisomes. Catalase protects the cell against
hydrogen peroxide toxicity through catalyzing dismutation reaction of H 2O 2
(B ARTOSZ , 1995).
Other studies have shown that CT activity clearly decreases in PIH placentas in comparison to normal placentas. Also the activity of other antioxidative
system enzymes (superoxide dismutase, glutathione peroxidase and glutathione
reductase) decreases in this disorder. In the present study both increase and
decrease of CT activity in pathological placentas was observed as compared to
normal placentas (K ONKOFER , 2001; B UHIMSCHI , 2001).
Uncontrolled increase of ROS level in oxidative stress conditions may
initially lead to antioxidative enzymes activation, causing activity augmentation, which is subsequently inhibited (WALSH , 1994; K LIMEK , 1998). It was
confirmed in our investigations. Therefore, it could be suggested that increase
or decrease in CT activity depends on the stage of pathological alteration
advancement in placental cells (symptoms of duration and intensification and/
or an applied treatment). On the basis of the obtained results a more meticulous approach to monitoring patients with PIH disorder seems to be advisable.
The results of this study concerning changes in CT activity in pathological placentas confirm occurrence of disturbances in oxidative system, which
are manifested as changes in antioxidative enzymes activity, whose direct cause
can be oxidative stress.
KATALAZA (CT) W £O¯YSKACH KOBIET Z NADCIŒNIENIEM
INDUKOWANYM CI¥¯¥ (PIH)
STRESZCZENIE
Badania aktywnoœci katalazy (CT) przeprowadzono na 10 ³o¿yskach
prawid³owych oraz 15 ³o¿yskach kobiet z zdiagnozowanym nadciœnieniem
indukowanym ci¹¿¹ (PIH). Wyniki naszych badañ wykaza³y ró¿nice w CT w
³o¿yskach patologicznych w porównaniu do ³o¿ysk z ci¹¿ prawid³owych. Aktywnoœæ
CT w ³o¿yskach prawid³owych utrzymywa³a siê na podobnym poziomie, natomiast
w ³o¿yskach powik³anych nadciœnieniem indukowanym ci¹¿¹ aktywnoœæ CT
spada wzglêdem aktywnoœci CT w ³o¿yskach prawid³owych. Zaobserwowano
pojedyncze przypadki wzrostu aktywnoœci CT w ³o¿yskach patologicznych.
Uzyskane przez nas wyniki dotycz¹ce zmian aktywnoœci CT w ³o¿yskach pacjentek
ze zmianami PIH potwierdzaj¹ udzia³ stresu oksydacyjnego w etiopatogenezie
nadciœnienia indukowanego ci¹¿¹.
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CATALASE-(CT)-ACTIVITY-IN-PLACENTAS
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Received 2002.11.14.