Ognjanović, Branka I.

Pavlović, Slađan

Saičić, Zorica

Štajn, Andraš Š.

Žikić, Radoslav V.

English

 Digital Repository of Archived Publications - Institute for Biological Research Sinisa Stankovic (RADaR)

Cadmium (Cd) has been recognized as being among the most
toxic environmental and industrial pollutants, one that is pres-
ent in soils, sediments, air, and water (S t o e p p l e r, 1991).
After penetrating into the organism, mostly through the respir-
atory and gastrointestinal tracts, Cd accumulates in the liver and
kidneys, as well as in other tissues and organs, causing many
metabolic, histological, and pathological changes, such as neph-
rotoxicity, cardiotoxicity, increased lipid peroxidation and hem-
orrhagic lesions of seminal tubules. In tissues, Cd also binds to
proteins of low molecular mass, producing metallothioneins by
the induction of metallothionein mRNA synthesis (G e o r g e
et al., 1996). Cadmium depletes glutathione and protein-bound
sulfhydryl groups, resulting in enhanced production of reactive
oxygen species (ROS). These ROS result in increased lipid per-
oxidation, enhanced excretion of urinary lipid metabolites,
modulation of intracellular oxidized states, DNA damage,
membrane damage, altered gene expression, and apoptosis
(K i m et al., 2003).
The main antioxidant functions of coenzyme Q10 (CoQ10)
are: to inhibit the process of lipid peroxidation and regenerate
the active form of vitamin E (E r n s t e r and B e y e r, 1991);
and to stabilize extracellular ascorbate in the organism (G o -
m e z - D i a z et al., 1997). It is known that CoQ10 protects
DNA from oxidation caused by lipid peroxidation and also pro-
tects the organism from oxidative stress induced by various tox-
ic agents (E r n s t e r and D a l ln e r, 1995).
Our experiments were carried out with male 60-day-old
white rats of Wistar strain weighing 190 ± 20 g at the onset of
experiments. They were kept in individual cages under con-
trolled conditions (light on from 5 a.m. to 5 p.m.; temperature
of 23 ± 2°C) and had free access to water and food. The animals
were divided into four experimental groups and treated for a pe-
riod of 30 days. The first group of animals was the control (C,
drinking tap water). The second group was treated with cadmi-
um (Cd, 200 mg of CdCl2 x 5H2O/l of drinking water for 30
days + 100 ml of olive oil, i.m., every fifth day). The third group
was treated with coenzyme Q10 (CoQ10, 40 mg of CoQ10/ml dis-
solved in olive oil, i.m., every fifth day, drinking tap water). The
fourth group was treated with cadmium and coenzyme Q10 con-
comitantly (Cd+CoQ10 in the above mentioned amounts). The
average intake of 17 mg Cd/day/kg body mass was calculated
from water consumed during the 30-day treatment. The average
intake of CoQ10 was 16 mg/kg body mass every fifth day. All
animals were invariably decapitated between 8 and 10 a.m. to
avoid any possible rhythmic variations in the antioxidant level.
The testes were dissected out within 3 min and prepared for fur-
ther analysis. All chemicals were from Sigma (St. Louis, MO,
USA). The concentration of ascorbic acid (AsA) was deter-
mined spectrophotometrically by the dinitrophenylhydrazine
method (R o e, 1957). Vitamin E (Vit E) concentration was as-
sayed by the method of  D e s a i (1984) using bathophenanthro-
line. Coenzyme Q (CoQ) was determined by the method of
B e y e r (1989). Protein content was determined by the meth-
od of  L o w r y et al. (1951) using bovine serum albumin as a
reference. Statistical analysis of the results was based on the
Student’s t test considering the a level of p < 0.05 to be signifi-
cant (H o e l, 1966). 
Data on AsA, Vit E, and CoQ concentrations are given and
compared to the control rats (C) in Table 1. The concentration
of AsA was significantly increased in relation to the controls in
all experimental groups, i.e., treated with Cd, with CoQ10 con-
comitantly (p<0.005), and with Cd+CoQ10 (p<0.01). Our earli-
er results on rat kidneys (P a v l o v i ć  et al., 2001) showed that
Cd induces elevation of AsA concentration after chronic treat-
ment. Increased concentration of AsA in testes of CoQ10-treat-
ed animals tallies nicely with increased concentration of Vit E
in these organs. It is known that AsA and Vit E are capable of
acting synergistically as antioxidants and that each can exert
sparing effects in relation to the other (T a n a k a  et al., 1997).
The data of G o m e z-D i a z  et al. (1997) also showed that
CoQ10 and its NADH-dependent reductaze stabilize extracellu-
lar ascorbate in the organism. The concentration of Vit E was
significantly higher in testes of animals treated with Cd, with
CoQ10, and with both Cd and CoQ10 concomitantly than in tes-
tes of the controls (p<0.005). Vitamin E radical (Vit E., a-tocop-
heroxyl radical) formed in the reaction with free lipid radicals
(LOO.) would be regenerated by the reduced form of CoQ10
(CoQ10H2), could explain the increased concentration of Vit E
in the testes of rats treated with CoQ10 (E r n s t e r and F o s -
m a r k - A n d r e e , 1993). Increased concentrations of Vit E
EFFECT OF COENZYME Q10 ON ASCORBIC ACID, VITAMIN E, AND COENZYME Q
CONCENTRATIONS IN TESTES OF RATS CHRONICALLY EXPOSED TO CADMIUM. S. Z.
Pavlović1, Branka I. Ognjanović2, A. Š. Štajn2, R. V. Žikić2 and Zorica S. Saičić1. 1Department of Physi-
ology, Siniša Stanković Institute for Biological Research, 11060 Belgrade, Serbia; and 2Institute of Biology,
Faculty of Science, University of Kragujevac, 34000 Kragujevac, Serbia.
Key words: Coenzyme Q10, rat exposure to cadmium, testes
UDC 591.463.2:612]:504.2
19P
Arch. Biol. Sci., Belgrade, 58 (3), 19P-20P, 2006.
20P
in the testes have a protective role against the toxic influence of
Cd, which represents a physiological adaptation of the organism
to toxic Cd effects. Contrary to AsA and Vit E, the concentra-
tion of CoQ in the testes was not significantly changed in any
of the investigated groups of animals in comparison with the
controls. Other authors performing dose- and time-dependent
studies demonstrated that CoQ concentration after parenteral
administration was increased only in the plasma and liver of rats
(S c a l o r i  et al., 1986).
It can be concluded that CoQ10 administration to rats
chronically exposed to exogenous Cd exerts beneficial effects
on AsA and Vit E concentrations in the testes, resulting in im-
proved antioxidant protection against Cd toxicity.
Acknowledgement - This research was supported by the Ministry of Sci-
ence and Environment Protection of the Republic of Serbia (Grant
143035B).
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TESTES 
K 
Cd 
CoQ10 
Cd + CoQ10 
 
AsA 
(mg/100 g tissue) 
15.20 ± 0.97 
         22.30 ± 0.79 **** 
         32.42 ± 0.88 ****  
       19.03 ± 0.85 *** 
 
Vit E 
(mg/g tissue) 
7.76 ± 0.06 
        12.39 ± 0.20 **** 
        12.86 ± 0.15 **** 
        14.61 ± 0.20 **** 
 
CoQ 
(nM/mg proteins) 
  626.83 ± 15.81 
  609.41 ± 19.62 
  593.37 ± 33.58 
  622.30 ± 15.13 
 
In relation to the controls (C): ***p<0.01; ****p<0.005 by Student¢s t test. 
 
Table 1. Concentrations of ascorbic acid (AsA), vitamin E (Vit E), and coenzyme Q (CoQ) in the testes of control rats (C) and rats
treated with cadmium (Cd), with coenzyme Q10 (CoQ10), and with cadmium and coenzyme Q10 concomitantly (Cd + CoQ10).
Values are means ± S.E. from seven animals.


Effect of coenzyme Q10 on ascorbic acid, vitamin E, and coenzyme Q concentrations in testes of rats chronically exposed to cadmium

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Effect of coenzyme Q10 on ascorbic acid, vitamin E, and coenzyme Q concentrations in testes of rats chronically exposed to cadmium

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