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 DOI: 10.1177/0748233709345942

2009 25: 479Toxicol Ind HealthRamazan Yilmaz, Recep Sutcu and Sadettin Caliskan

Bumin Dundar, Gokhan Cesur, Selcuk Comlekci, Ahmet Songur, Alparslan Gokcimen, Onder Sahin, Ozlem Ulukut, H.development and IGF-1 levels in female Wistar rats

The effect of the prenatal and post-natal long-term exposure to 50 Hz electric field on growth, pubertal  

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The effect of the prenatal and post-natallong-term exposure to 50 Hz electricfield on growth, pubertal developmentand IGF-1 levels in female Wistar rats

Bumin Dundar1, Gokhan Cesur2, Selcuk Comlekci3, Ahmet Songur4,Alparslan Gokcimen5, Onder Sahin6, Ozlem Ulukut3, H Ramazan Yilmaz7,Recep Sutcu8 and Sadettin Calıskan2

AbstractTo investigate prenatal and post-natal effects of extremely low frequency (ELF) electric field (EF) on growth and pub-ertal development, pregnant Wistar rats were randomly distributed among three groups. The pregnant rats of theprenatal group were exposed to 24-hour EF at 50 Hz EF 10 kV/min during pregnancy and their subsequent randomlyselected female pups continued to be exposed until puberty. The post-natal group was unexposed to EF during preg-nancy, but randomly selected female pups from this group were exposed to EF between delivery and puberty at thesame doses and duration as the prenatal group. The third group was a sham-exposed group. The mean birth weightand weight gain of the pups during study period were found significantly reduced in prenatal group than post-nataland sham-exposed groups (p < 0.001). No difference could be found among the three groups for body weight atpuberty (p > 0.05). The mean age at vaginal opening and estrous were significantly higher at prenatal group thanpost-natal and sham-exposed groups (p < 0.001). Serum insulin-like growth hormone-1 (IGF-1) levels were foundsignificantly reduced in prenatal exposure group compared with the other two groups (p < 0.001). There was nodifference for birth weight, weight gain, the mean age at vaginal opening and estrous and IGF-1 levels betweenpost-natal and sham-exposed groups (p > 0.05). There was also no difference for FSH, LH and E2 levels at pubertyamong the three groups (p > 0.05). Histological examination revealed that both the prenatal and post-natal groupshad the evidence of tissue damage on hypothalamus, pituitary gland and ovaries. In conclusion, early beginning ofprenatal exposure of rats to 24 hours 50 Hz EF at 10 kV/m until puberty without magnetic field (MF) resulted ingrowth restriction, delayed puberty and reduced IGF-1 levels in female Wistar rats. These effects probably associ-ated with direct toxic effects of EF on target organs. Post-natal exposure to EF at similar doses and duration seems tobe less harmful on target organs. Post-natal exposure to EF at similar doses and duration seems to be less harmful.

Keywords50 Hz, electric field, extremely low frequency, growth, IGF-1, puberty

1 Department of Pediatric Endocrinology, Suleyman Demirel University, Cunur, Isparta, Turkey2 Department of Physiology Faculty of Medicine, Suleyman Demirel University, Cunur, Isparta, Turkey3 Department of Electronics and Communication Engineering, Suleyman Demirel University, Cunur, Isparta, Turkey4 Department of Anatomy, Kocatepe University, Afyon, Turkey5 Department of Histology and Embriology, Suleyman Demirel University, Cunur, Isparta, Turkey6 Department of Pathology, Kocatepe University, Afyon, Turkey7 Department of Medical Biology, Suleyman Demirel University, Cunur, Isparta, Turkey8 Department of Biochemistry, Suleyman Demirel University, Cunur, Isparta, Turkey

Corresponding author:Bumin Dundar, Department of Pediatric Endocrinology, Faculty of Medicine, Suleyman Demirel University, Cunur 32260, Isparta,Turkey. Email: bumindundar@gmail.com

Toxicology and Industrial Health25(7) 479–487ª The Author(s) 2009Reprints and permission: http://www.sagepub.co.uk/journalsPermission.navDOI: 10.1177/0748233709345942tih.sagepub.com

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Introduction

Since the numbers of electromagnetic devices have

increased due to industrial development during last

decades, the intensity and variety of exposure to elec-

tric fields (EF) and/or magnetic fields (MF) of organ-

isms living in land have grown dramatically.

Therefore, their possible biologic effects on human

health have continued to be a controversial issue and

have continued to receive increasing scientific interest.

The electric power frequency chosen was of 50 or

60 Hz. These frequencies can be placed in the band of

extremely low frequency. The effects of extremely

low frequency electromagnetic field (EMF) on biolo-

gical parameters, in vivo and in vitro, have been

reported in many studies, but most of the recent stud-

ies focused on the side effects of MF components

(World Health Organization, 1984; Repacholi and

Greenebaum, 1999). There is a lack of data regarding

the biologic effect of pure EF in the current literature.

Whereas, exposure to extremely low frequency (ELF)

EF without MF is not rare in daily life and some prod-

ucts like the electric charges and power lines may

interact with or produce EF in live cells, which result

in enormous dielectric responses.

Many post-natal biological events are programmed

at the intrauterine life and it is well known that expo-

sure to environmental agents at this period usually may

affect prenatal and post-natal growth, and development

of neurological and reproduction systems of fetus ini-

tially (Barker, 1995; Hales and Barker, 2001).

Although the accepted exposure limit is about 10 kV/

m at power frequencies for EF (World Health Organi-

zation, 1984; ICNIRP, 1998), it should be taken into

consideration that the organism may be more sensitive

to the effect of environmental agents during pregnancy.

For this reason, the effects of prenatal exposure of ELF

EF on prenatal and post-natal growth have been inves-

tigated in several studies (Sikov et al., 1984; Portet and

Cabanes, 1988; Rommereim et al., 1989, 1990).

Although the majority of well-conducted studies have

failed to demonstrate any adverse effects of EF and/

or EMF exposure on growth and development, con-

flicting results have also been reported. On the other

hand, some important peptides like insulin-like growth

hormone-1 (IGF-1) that has an important role on the

growth of dams in prenatal and post-natal life, which

were evaluated in a small part of these studies and

inconsistent results have been obtained about the effect

of EF on IGF-1 levels (Rodriguez et al., 2002; Burch-

ard et al., 2004, 2007)

The reproductive system has been thought of as a

major target of EMF and the effect of EMF on repro-

ductive system of humans and animals have also been

investigated in many studies (Rommereim et al., 1989,

1990; Juutilainen, 2005; Al-Akhras et al., 2006; Khaki

et al., 2006; Cao et al., 2006; Davis et al., 2006). How-

ever, most of these studies generally have addressed

the effects of EMF on reproduction and fertility and its

relation to MF. The possible effects of long-term expo-

sure to ELF EF, especially on pubertal development,

have not been evaluated adequately yet.

This study was designed to investigate the effects

of prenatal and post-natal long-term 24-hour exposure

to 50 Hz ELF EF on prenatal and post-natal growth,

pubertal development, IGF-1 levels, and some endo-

crine glands related to puberty, such as hypothalamus,

pituitary gland and gonads of female Wistar rats.

Materials and methods

Study design

The study was approved by the Institutional Review for

Animal Research Board of Suleyman Demirel Univer-

sity and was conducted in accordance with the institu-

tional guidelines. Twenty-four 5-month-old female

Wistar albino rats were mated with 24 male rats in the

study. Each rat was placed into the cage overnight with

a male rat, and the first 24-hour period following the

mating procedure was designated as day 0 of pregnancy.

Firstly, all pregnant female rats were placed into

one cage and they were randomly distributed among

three groups (n ¼ 8) as prenatal, post-natal and

sham-exposed (control) groups. The pregnant rats of

prenatal group were exposed to 24-hour EF at

50 Hz EF 10 kV/min during pregnancy and their pups

continued to be exposed to EF after delivery. The

post-natal group was unexposed to EF during preg-

nancy, but the pups from this group were exposed to

EF at delivery. The third group was the sham-

exposed group. Pups that were born in the field

remained with their dams through the suckling period.

At 21 days of age, eight female rats from each group

were subsequently randomly selected and isolated.

The female pups from prenatal and post-natal groups

continued to be exposed to 24-hour EF at 50 Hz EF

10 kV/min. Female pups selected from the control

group were sham exposed to EF until puberty. Blood

samples were obtained and rats decapitated when

vaginal opening and estrous were detected.

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All pups were fed with breast milk and standard

food during the first 21 days of their lives. After

weaning, rats in all groups were continually fed with

standard food. All animals were fed ad libitum and

subjected to normal daylight cycles (08.00-20.00) at

normal room temperature (21-22�C). During experi-

ments, all animals were provided with the same feed-

ing and watering process. Groups were kept at the

same environmental conditions (humidity (55-60%),

temperature, light intensity and electromagnetic

fields). In the same room, the sham-exposed and

exposure groups were separated by custom-made

stainless steel shield (Figures 1 and 2).

According to the standards and regulations of Insti-

tute of Electrical and Electronic Engineers (IEEEE)

and World Health Organization (WHO), power fre-

quency exposure limit is 10 kV/m (World Health

Organization, 1984; ICNIRP, 1998). For this reason,

we decided to use about 10 kV/min EF intensity in

power frequency, 50 Hz, pure EF condition in this

study.

All animals had EF exposure for a duration of 24

hours a day. These animals were exposed to EF during

life in the experimental room.

The weight of the rats was measured weekly and

genital examinations were performed twice a day to

determine vaginal opening after 15 days of age. Vagi-

nal smear was taken to evaluate cornified epithelium

after vaginal opening. The day of vaginal opening and

determination of cornified epithelium were recorded

as the time of the onset of the puberty.

At the end of the study, all animals were decapi-

tated under ether anesthesia. Blood samples were

collected from the inferior vena cava and separated

by centrifugation at 3000 rpm for 10 min, and the

serum was stored at �80� C until use. At the end of

the procedure, the rat brains (right hemispheres),

pituitary glands and ovaries (right) were removed

immediately for histological examination.

Electric field application set-up

Exposure system: In this study, a custom-made paral-

lel plate exposure system was used. It was planned,

constructed and tested in the Antennas and Propaga-

tion Laboratory of Department of Electronics and

Communication Engineering at Suleyman Demirel

University. From the basic electromagnetic theory,

the E field lines in a set of parallel plate and field

between them is highly uniform. The plates’ effective

area is 0.5 m2 (0.5 � 1.0 m) and space between the

plates is d(variable 0.1-1.0 m) to avoid changing

value of field between plates at power frequency

range (Comlekci, 2006) This set-up is suitable to

use for small animal studies because the size of a

Figure 1. Schematic view of the electric field application set-up.

Figure 2. The appearance of the electric field applicationset-up.

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6-8-animal cage is about 40 � 50 � 20 cm3 (w � l �h), with 2 mm thickness. A perfect conductor (stain-

less steel) was used in construction of plates because

free surface charges can be homogenous in order to

get uniform fields.

The set-up was schematically illustrated in

Figure 1. The EF strength was calculated according

to the equation E ¼ Vd

where E is electric potential

between the plates, d is the distance, and E is the

EF intensity in volt/meter. The corners were rounded

to get rid of corruptions due to end effect. They were

placed upright on wooden stands and positioned paral-

lel to each other. In order not to disturb the field, leads

were connected to the center of the plates on their outer

sides (Aydin et al., 2006; Okudan et al., 2006).

In the exposure system, a step-up transformer rated

220 Vrms/5000 Vrms and 1000 VA was used. The

plates were spaced at 50 cm in distance. Cages were

adequately sized to ensure free movement of rats and

their pups, hence homogenous shielding of each other.

In addition to weekly cleanups of the plates and cages,

the set-ups were frequently scrutinized for gross soil

and wetness that would disturb the homogeneity of

EF. The attenuation due to routine soiling could be

estimated to cause very small variation in EF. From

the equation above, average EF density, between the

plates, were calculated to be 5000 V/0.5 m ¼10,000 V/m (10 kV/m) in EF group. Multimeter (Max

3000 TRMS Model Chauvin Arnoux, Paris, France)

was used for voltage measurements. Primary voltage

of power transformer, secondary voltage and EF den-

sity were in the range of 219-229 Vrms, 4975-5202

Vrms and 9951-10405 V/m, respectively. Digital

Gauss/Tesla Meter (Unilab, Blackburn, UK) was

used to test the purity of EF from background MFs.

Maximum MF density was about 0.001 mT. In the

experiment room, unwanted high-frequency fields

were tested by using HI-3804 Electromagnetic Field

Survey Meter-Industrial Compliance Meter and its

probe (Holaday Industries, Inc, UK).

Histopathological examination

Hypothalamus and pituitary gland: Specimens were

fixed in 10% neutral buffered formaldehyde solution.

After dehydration procedures, the samples were

blocked in paraffin. Five micrometer thick sections

of hemispheres including the hypothalamus and pitui-

tary were cut by a microtome and stained with

hematoxylin-eosin. Mounted slides were examined

under a light microscope (Nikon Microscope

ECLIPSE E600W, Tokyo, Japan) and photographed

using a digital camera (Microscope Digitale Camera

DP70, Tokyo, Japan). In the evaluation of hypothala-

mus sections, the distribution apoptotic changes

(pycnosis and karyorhexis), edema, cellular disorga-

nization and vacuolization were defined as criteria.

Apoptotic changes reduced in basophilic and acido-

philic cells ratio (normally 1/5) and vascular conges-

tion was defined as criteria in the pituitary gland.

These criteria were scored 0-3 (no, low, moderate and

high, respectively) as semi-quantitatively.

Ovaries: Ovarian tissues were fixated in 10% neu-

tral formaline solution. After performing routine tissue

processing procedures, samples were embedded in par-

affin blocks. For microscopic evaluation, 15 sections

were cut from each block by using systematical rando-

mized sampling method. All sections were stained with

hematoxyline-eosine dye. Stained sections were exam-

ined under Olympus-BX 50 light microscope.

Hormone analysis

Follicle stimulating hormone (FSH), luteinizing hor-

mone (LH) and estradiol (E2) were measured in

Architect System (2002 Abbott, Germany) by chemi-

luminescense method for the quantitative determina-

tion on the human serum. IGF-1 levels were also

analysed using chemiluminescense assay by Immulite

2000 kits (BIODPC, LA, USA).

Statistical analysis

SPSS 11.0 software for Windows was used for statis-

tical analysis of the data. The data were presented as

means + standard error of mean (SEM). Kruscal-

Wallis and Mann-Whitney U tests were performed for

group comparisons. p Values of less than 0.05 were

considered as statistically significant.

Results

The data of the mean body weight at delivery and pub-

erty, weight gain during study period and age at vaginal

opening and estrous of the pups at prenatal, post-natal

and sham-exposed groups are shown in Table 1.

The mean birth weight and weight gain during study

period were found significantly reduced in the prenatal

group compared with the post-natal and the sham-

exposed groups (p < 0.001). There was no difference

for the mean birth weight and weight gain during study

period between the post-natal and sham-exposed

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groups (p > 0.05). Body weights of the three groups at

puberty were not significantly different (p > 0.05).

The mean age at vaginal opening and estrous of

three groups are shown in Table 1. Age at vaginal

opening and estrous were significantly higher in prena-

tal groups than in post-natal and sham-exposed groups

(p < 0.001). Vaginal opening time of the post-natal and

sham-exposed groups were similar (p > 0.05).

Serum FSH, LH and E2 levels of groups at puberty

are presented in Table 2. No significant difference for

these hormonal parameters could be detected (p > 0.05).

Serum IGF-1 levels were shown in Figure 3. IGF-1

levels were found significantly reduced in prenatal

exposure group (p < 0.001). No significant difference

was present in IGF-1 levels of the post-natal and the

sham-exposed groups (p > 0.05).

The results of the histopathological examinations

of the hypothalamus and pituitary glands are summar-

ized in Table 3. Increases in degenerative changes

including apoptotic changes, edema, cellular disorga-

nization, vacuolization, reduce in basophilic and acid-

ophilic cells ratio (normally 1/5) and vascular

congestion were determined in prenatal and post-

natal groups. The degenerative signs for both tissues

were more evident in prenatal group than post-natal

exposure group (Figures 4 and 5).

Normal follicles cannot be seen in cortical region

of ovarian tissue obtained from the prenatal and

post-natal groups. There are some other follicles with

developmental degeneration, connective tissue

increment and fibrosis. Especially the primordial and

primary follicles are absent in both groups.

Table 2. Serum FSH, LH and E2 levels of three groups atpuberty

Prenatal Post-natal Control p

FSH (IU/L) 1.05 + 0.1 1.21 + 0.3 1.44 + 0.6 >0.05LH (IU/L) 0.96 + 0.12 1.11 + 0.2 1.22 + 0.31 >0.05E2 (pg/mL) 21.4 + 0.92 23.8 + 2.1 20.8 + 1.55 >0.05

FSH, follicle stimulating hormone; LH, luteinizing hormone; E2,estradiol.

Table 1. The mean body weight at delivery, weight gain per month during study period and the age at vaginal opening andestrus of the pups at prenatal, post-natal and control groups

Prenatal Post-natal Control p

The mean body weight at delivery (g) 3.07 + 0.07 4.80 + 0.08 5.6 + 0.09 <0.001The mean body weight at vaginal opening (g) 72.3 + 4.3 73.3 + 2.3 70.6 + 6.3 >0.05Weight gain per month during study period (g) 21.20 + 2.6 27.610 + 1.8 32.3 + 2.1 <0.001Age at vaginal opening (day) 93.7 + 3.9 71.7 + 4.79 67.7 + 3.52 <0.001Age at estrous (day) 93.8 + 3.9 81.2 + 4.2 68.6 + 3.1 <0.001

Figure 3. Serum insulin-like growth hormone-1 (IGF-I)levels of the three groups at puberty (9.4 + 2.6, 24.33 +5.3 and 30.2 + 6.5 ng/mL, respectively, p < 0.001).

Table 3. The semiquantitative histopathological scores incontrol, prenatal and post-natal magnetic fields groups’hypothalamus and pituitary

Prenatal Post-natal Control

HypothalamusApoptotic changes 3 1 0Edema 2 2 0Cellular disorganization 2 2 0Vacuolization 2 3 1

Pituitary glandApoptotic changes 3 2 2Reduce in basophilic

and acidophiliccells ratio

2 1 0

Vascular congestion 2 1 1

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Discussion

Although there are a few conflicting results about the

adverse effects of EF and/or EMF on growth and

development, the majority of the previous studies

involved large group size using 60 Hz or 50 Hz EF,

and field strengths from 10 to 150 kV/m reported no

adverse effect on growth and development. Portet and

Cabanes (1988) reported that exposure to 50 Hz

50 kV/m EF did not induce significant effects on

growth and development in 8-week-old male rats

exposed 8 hours per day for 4 weeks or rabbits

exposed 16 hours per day from the last 2 weeks of

gestation to 6 weeks after birth. In their other study,

application of 50 Hz EF on rabbits with a dose of

8 hours per day started 6th day of gestation resulted

in no any body and organ growth retardation (Portet

et al., 1984). In contrast, Rommerein et al. (1990)

observed slightly depressed weight gain of dams dur-

ing gestation and more weight loss during lactation

period in rats exposed to 60 Hz EF in high field

strengths. Although the presence of MF makes this

study different from our study, a recent study per-

formed by Cao et al. (2006) reported slower body

weight increase in offsprings prenatally exposed to

50 Hz, 1.2 mT 8 hours per day EMF than the sham-

exposed group in the first 2 weeks of life. In this

study, lower birth weight, reduced post-natal growth

and delayed puberty with reduced levels of IGF-1,

have been observed in pups of rats exposed to long-

term 24/hour 50 Hz 10 kV/m EF during prenatal and

post-natal period compared with post-natal and sham-

exposed groups. However, our study seems to be in

discordance with the majority of data of previous

studies. It is clear that our inconsistent results might

be associated with the differences in animals in used

Figure 5. The representative photomicrographs pituitary gland sections are subjected to prenatal (A), post-natal (B) andcontrol (C). VC, vascular congestion; black arrow, acidophilic cell; and white arrow, basophilic cell, hematoxylin-eosin(H/E) �200 CI.

Figure 4. The representative photomicrographs of hypothalamus sections are subjected to prenatal (A), post-natal (B)and control (C). Black arrow, vacuolization; white arrow, hematoxylin-eosin (H/E) �200.

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previous studies. On the other hand, we think that

starting off exposure to 50 Hz EF at the first day of

pregnancy and 24 hour/day exposure differentiate our

study from most of the previous studies and might

explain how these adverse effects occurred especially

the in prenatal exposure group. It is well known that

timing and duration of environmental effects are very

important during prenatal period.

In this study, while the adverse effects of ELF EF on

growth and pubertal development of prenatal group

have been clearly detected, these parameters for the

post-natal exposed group were found similar with the

sham-exposed group. Our results seem to be consistent

with the literature reporting the lack of the adverse

effect of EF exposure on post-natal and adult life (Juu-

tilainen, 2005). These data indicate that the side effects

of ELF EF on growth and development are more

important, especially during the early prenatal period.

The absence of post-natal catch-up growth of pups

on the prenatal exposure group in the present study

could bring to mind that intrauterine growth was

affected in early stage of embryogenesis in prenatal

EF exposed group. The genotoxic potential effects of

EF and MF, which have been reported previously, sup-

port our consideration (McCann et al., 1998).

It has been known that IGF-1 has a very important

role on fetal and post-natal growth. The variations in

IGF-1 levels associated with EMF exposure have

been reported in a few previous studies. Rodriguez

et al. (2002) observed increased IGF-1 levels in preg-

nant lactating cows exposed to 16 hours vertical EF of

60 Hz 10 kV/m and a horizontal MF of 30 mT. How-

ever, the study of Burchard et al. (2004) did not con-

firm these results in which IGF-1 levels on pregnant

dairy heifers exposed to 10 kV/M 60 Hz EF could not

been detected significantly different than sham-

exposed groups. Nevertheless, in their recent study,

slight decrease in concentration of IGF-1 of pregnant

dairy heifer was reported with 60 Hz and 30 mT EMF

exposures (Burchard et al., 2007). IGF-1 levels were

found significantly lower in prenatal exposure group

than the post-natal and sham-exposed groups in this

study. It can be thought that the lack of catch-up

growth of prenatal exposure rats might be associated

with low IGF-1 levels. To explain how EF caused

reduced IGF-1 levels is difficult. It may depend on the

toxic effect of EF on target organs. On the other hand,

we think that reduced IGF-1 levels might also be

related to maldigestion and/or malabsorbtion associ-

ated with EF effects. Because there is a close relation-

ship between IGF-1 levels and nutrition as well as

growth hormone levels, and nutritional status is the

most important factor during prenatal and early

post-natal life and body weight losses under restricted

diets are associated with reduction in IGF-1 blood

concentrations (Turan et al., 2007; Leon et al.,

2004). However, we did not measure food consump-

tion in the present study and it seems to be the limita-

tion of our study. To clarify the reason of low IGF-1

levels associated with EF, more studies are needed.

There are conflicting results regarding the effects

of ELF EF without MF on reproduction in the litera-

ture. Rommereim et al. (1987) found a statistically

significant decrease in fertility of female rats exposed

to 60 Hz 100 kV/m EF. Nevertheless, they could not

show similar effects on reproduction of rats with

exposure of 60 Hz 150 kV/m EF in their another

study (Rommereim et al., 1989). A significant reduc-

tion in the fertility of adult male and female Sprague

Dawley rats was found after 90 days of exposure to a

50 Hz, 25 mT EMF (Al-Akhras et al., 2001). Hong

et al. (2003) has also reported adverse effects on

reproduction in male rats at similar doses. However,

another study did not confirm these results at the same

doses (Elbetieha et al., 2002). In a recent study, Al-

Akhras et al. (2006) reported a significant decrease

in sperm count, the weights of seminal vesicles and

testosterone levels in the exposed male rats and sug-

gested that long-term exposure to ELF could have

adverse effects on mammalian fertility and reproduc-

tion. There is a lack of study investigating the effect of

ELF EF on pubertal development. In a previous study,

the vaginal opening time of female rats exposed to

ELF EMF has been reported to be identical with that

of the sham-exposed groups (Chung et al., 2004).

However, delayed puberty was detected in the prena-

tal exposure group compared with post-natal and

sham-exposed groups in the present study. As men-

tioned before, it can be considered that intrauterine

growth retardation and absence of catch-up growth

with low IGF-1 levels might lead to delay in puberty

in prenatal exposure group. The presence of statisti-

cally identical levels of FSH, LH and E2 of three

groups at puberty support this point of view. How-

ever, histological evidence of degenerative findings

in hypothalamus and pituitary gland which were

clearer especially, in pre-natal exposure group and

ovaries indicate that direct toxic effect of ELF EF

on target organs might also contribute to this condi-

tion. We think that degenerative findings on these tis-

sues might be related to the effect of EF on membrane

transport mechanisms and electropermeabilization of

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the cells, which can cause biochemical and physiolo-

gical changes in the cell. Because it has been shown

that application of EF to the cell may cause exceeding

in threshold value of the transmembrane potential and

allowing entrance of molecules that otherwise cannot

cross the membrane and further increase in EF inten-

sity may cause irreversible membrane permeabiliza-

tion and cell death (Mir, 2001; Valic et al., 2003).

All side effects have been seen in lower strength

field in this study compared with other studies. This

finding shows that beginning and duration of exposure

time seems to be the more important factors than the

severity of strength field in prenatal side effects of EF.

In conclusion, exposure to 50 Hz 10 kV/sec EF

from the beginning of prenatal period until puberty

without MF resulted in growth restriction, delayed

puberty and reduced IGF-1 levels in female Wistar

rats. Further studies are needed to explain the effect

of 50 Hz EF on intrauterine and post-natal growth,

pubertal development and relation to growth factors.

Acknowledgement

This study was supported by Suleyman Demirel University

Scientific Research Projects Unit (project number: 1052-

m-05).

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