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NeuroQuantology | December 2013 | Volume 11 | Issue 4 | Page 582-590
Odacı et al., Effects of 900 Megahertz EMF in the prenatal period on hippocampus and learning behavior
eISSN 1303-5150
www.neuroquantology.com
582
The Effects of Prenatal Exposure to a 900
Megahertz Electromagnetic Field on
Hippocampus Morphology and Learning
Behavior in Rat Pups
Ayşe İkinci*, Ersan Odacı*, Mehmet Yıldırım
†
, Haydar Kaya
‡
,
Metehan Akça
†
, Hatice Hancı*, Ali Aslan
§
, Osman Fikret Sönmez
ll
, Orhan Baş**
ABSTRACT
The purpose of this study was to examine the effect on hippocampus morphology and learning behavior in rat pups
following prenatal exposure to a 900 megahertz (MHz) electromagnetic field (EMF). Female Sprague Dawley rats
weighing 180-250 g were left to mate with males. The following day, pregnant rats identified as such by the vaginal
smear test were divided into two groups, control (n=3) and EMF (n=3). No procedures were performed on the control
group. The rats in the EMF group were exposed to 900 MHz EMF on days 13 to 21 of pregnancy, for 1 h a day. Female
rat pups were removed from their mothers at 22 days old. We then established two newborn rat groups, a 13
member control group and a 10 member EMF group. Radial arm maze and passive avoidance tests were used to
measure rat pups’ learning and memory performance. All rats were decapitated on the postnatal 32nd day. Routine
histological procedures were performed on the brain tissues, and sections were stained with Cresyl fast violet. The
radial arm maze (p=0.007) and passive avoidance (p=0.032) tests were administered to both groups under identical
conditions, and compromised learning behavior was determined in the EMF group rats. Morphological compromise
was also determined in the EMF group sections. Our results show that the application of a 900 MHz EMF in the
prenatal period adversely affected female pups’ learning behavior and also resulted in histopathological changes
appearing in the hippocampus.
Key Words: newborn female rats, hippocampus, electromagnetic field, learning behavior
NeuroQuantology 2013; 4:582-590
Introduction
1
The rapid growth of technology and the
intensive use in daily life of devices that
Corresponding author: Ersan Odacı
Address: *Department of Histology and Embryology, School of
Medicine, Karadeniz Technical University, Turkey.
†
Department of
Physiology, School of Medicine, Karadeniz Technical University, Turkey.
‡
Department of Electrical and Electronics Engineering, Faculty of
Engineering, Karadeniz Technical University, Turkey.
§
Department of
Physiology, School of Medicine, Sakarya University, Turkey.
ll
Department of Neurosurgery, Samsun Education and Research
Hospital, Turkey. **Department of Anatomy, School of Medicine, Ordu
University, Turkey.
Phone: +90 462 3777729 and Fax: +90 462 325 2270
e-mail eodaci@gmail.com; eodaci@yahoo.com
This study was given as an oral presentation at the Controversies on
Electromagnetic Field in Medicine and Biology Symposium, Turkey,
Samsun, June 17 2013.
Received: September 13, 2013; Revised: October 20, 2013;
Accepted: December 1, 2013
produce an electromagnetic field (EMF) effect
pose a number of health problems. There is no
doubt that due to their being used close to the
head and being accessible to people of all ages,
with the exception of babyhood, mobile phones
head the list of such devices (Barcal and Vozeh,
2007; Odaci et al., 2008; Wigle et al., 2008).
Mobile phones can also be described as the
technological devices that most expose humans
to the effect of EMF. However, these marvels of
technology that produce considerable revenues
for companies involved with mobile phones, are
regarded as harmless due to the written and
visual advertizing appearing in the media.
Despite all the innocent and marvelous
impressions given, research into the subject is
increasingly raising doubts concerning the
NeuroQuantology | December 2013 | Volume 11 | Issue 4 | Page 582-590
Odacı et al., Effects of 900 Megahertz EMF in the prenatal period on hippocampus and learning behavior
eISSN 1303-5150
www.neuroquantology.com
583
effect of the EMF emitted by mobile phones
(Odaci et al., 2008; Bas et al., 2009a; 2009b;
Sonmez et al., 2010; Hancı et al., 2013). The
mobile phone and all aspects of its probable
effects on human health are therefore attracting
considerable interest from researchers.
Studies investigating the effect of the
EMF emitted by mobile phones using
stereological methods (Kaplan et al., 2012a;
2012b; İkinci et al., 2013; Aktürk et al., 2013)
have shown that quantitative losses at the
cellular level may develop in the brains and
brain-related structures of rats exposed to the
effect of 900 MHz EMF in both the prenatal
(Bas et al., 2009b; Odaci et al., 2008) and
postnatal (Bas et al., 2009a; Sonmez et al.,
2010) periods. These studies encourage the
investigation of the kind of effect exposure to
EMF in the prenatal or postnatal terms will
have on behavior. That is because an agent that
causes losses at the cellular level will very
probably also affects behaviors for which these
cells are responsible.
Studies investigating the relationship
between EMF and behavior have reported
differing results. While some studies report that
there may be problems with learning and
memory in rats exposed to the effect of 900
MHz EMF (Dubreuil et al., 2002; Hao et al.,
2013), others report the exact opposite
(Dubreuil et al., 2003; Kumlin et al., 2007). For
example, one study on rats using the eight-arm
maze test showed that long-term EMF (916
MHz, 10 w/m
2
) administered for approximately
10 weeks (5 times a week) for 6 h a day
compromised spatial memory (Hao et al.,
2013). On the other hand, it has also been
reported that neither spatial nor non-spatial
memory were affected by EMF in rats exposed
to 900 MHz EMF (Specific absorption rate
(SAR) = 1 and 3 W/kg) (Dubreuil et al., 2003).
Another study on mice reported no adverse
effect on spatial memory caused by 900 MHz
EMF (SAR = 0.05 W/kg) (Sienkiewicz et al.,
2000).
Studies investigating the effect on the
cognitive functions of rodents of EMF caused by
mobile phones have particularly concentrated
on different postnatal periods. To the best of
our knowledge, however, there are insufficient
studies investigating the effect of exposure to
EMF emitted by mobile phones on cognitive
functions in the prenatal period, the initial and
most sensitive period of brain development
(Rodier, 1980; Weinstock, 2001; Sakatani et al.,
2002; Tunc et al., 2007). The purpose of this
study was therefore to determine the probable
changes that 900 MHz EMF applied between
days 13 and 21 of the prenatal period would
cause in female rats’ behaviors and
hippocampus morphology.
Materials and methods
Acquisition of newborn rats and
establishment of newborn groups
At the beginning of the study, 14 female and 14
male rats (6-8 weeks old, weighing 180-250 g)
were mated for the purpose of obtaining
pregnant rats. These animals were obtained
from the Karadeniz Technical University
Surgery Research Center (KTUSRC), Turkey.
They were kept in the KTUSRC in standard
plastic cages on sawdust bedding in an air-
conditioned room at 22 ± 1
0
C under a 12-h
light/12-h dark cycle. Ad libitum access to
standard rat chow and tap water was allowed.
Approval for the study was granted by the
Karadeniz Technical University Faculty of
Medicine Experimental Animal Ethical
Committee. All Animal experiments and
procedures were conducted in compliance with
the U.S. National Institutes of Health Guide for
the Care and Use of Laboratory Animals. On the
evening of the first day, those of the 14 female
rats exhibiting two regular cycles were placed in
the same cages as male rats for mating
purposes. The vaginal smear test was used on
the following day to determine pregnancy. Rats
whose smear specimens contained sperm were
regarded as pregnant. That day was taken as
day 0 of pregnancy. Six rats were identified as
pregnant. These were then randomly divided
into two groups containing three rats each. No
procedures were performed on the first, control
group (CG) during pregnancy. The other three
rats were adopted as the EMF group (EMFG).
These were placed inside a Plexiglas jar for 1 h
at the same time every day, between days 13
and 21 of pregnancy, where they were exposed
to EMF of 900-MHz. Apart from the application
of EMF, no procedure was performed on the
rats during the hour they spent in the Plexiglas
jar, and they were allowed to move around
freely.
Pregnant rats were placed in individual
cages before giving birth. After birth, pups were
allowed to feed naturally with their own
mothers in the same cages. The newborn rats
were not subjected to any procedure after birth.
Thirteen female rat pups were obtained from
NeuroQuantology | December 2013 | Volume 11 | Issue 4 | Page 582-590
Odacı et al., Effects of 900 Megahertz EMF in the prenatal period on hippocampus and learning behavior
eISSN 1303-5150
www.neuroquantology.com
584
the control group mother rats and 11 from the
experimental group rats. The study proceeded
with 24 female rat pups. Female pups obtained
from control group mother rats were classified
as the newborn control group (NCG) and female
pups from EMF group mothers as the newborn
EMF group (NEMFG). Female rat pups were
kept in the same cages as their mothers until
the 22
nd
day after birth, and were allowed to
feed naturally with no procedure being
performed. On the postnatal 22
nd
day, they were
removed from their mothers and placed in a
separate cage. The rat pups were kept for 4 days
under the same laboratory conditions, with
access to standard rat chow and tap water, in
order for anxiety caused by separation from
their mothers to subside (Savignac et al., 2011).
One rat pup from the NEMFG died during this
time. The study thus continued with a total of
23 newborn female rats, 13 in NCG and 10 in
NEMFG. When the rats were 26 days old,
learning and memory tests began. The eight
arm radial maze test was applied to test rats’
spatial memory (Hao et al., 2013), the passive
avoidance test in order to investigate passive
avoidance behavior (Yildirim and Marangoz,
2004) and the open field test to examine
locomotor efficacy. The study was concluded on
the 32
nd
day postnatally.
EMF exposure system
A special EMF exposure room was prepared in
the KTUSRC, compatible with normal
laboratory conditions but containing only the
EMF exposure system, solely for the application
of 900 MHz EMF to NEMFG. NEMFG rats were
only placed in this room during EMF
application. Apart from during exposure to the
900 MHz EMF, the groups were kept in
different cages but in the same room. EMFG
rats were separated from CG animals for EMF
exposure, which took place in the EMF
exposure room. The EMF exposure system
consisted of an ultra-high-frequency oscillator
(1218-BV, Lockable Oscillator, 900–2000 MHz,
General Radio Company, Concord,
Massachusetts, USA, Serial No. 1483) with a
constant power source (1267-B Regulated
Power Supply, General Radio Company,
Concord Massachusetts, USA, Serial No. 903)
(with output power of approximately 300 mW
and a frequency adjusted to 900-MHz) and a
Plexiglas jar specifically produced for the study
(30 cm X 42 cm X 52 cm). The oscillator was
connected to a half-wave dipole antenna made
from a 1 mm x 15 cm copper rod by means of a
coaxial cable. The antenna was inserted into the
central area of the jar, approximately 11 cm
inside the open surface of a glass jar (Hancı et
al., 2013). EMFG pregnant rats were placed
inside the jar and exposed to 900-MHz EMF for
1 h (at the same time each day). Positional
averaging of electrical field intensity was
calculated using a wide-range measuring device
with a measurement range of 100 kHz-2.5 GHz
(Chauvin Arnoux CA43 Isotropic Electrical
Field Intensity Meter).
Radial Arm Maze Test
The eight arm radial maze apparatus was made
from wood. It was 50 cm from the ground, with
dimensions of 50 x 12 x 24 cm and consisted of
eight arms of the same size and a central area
40 cm in diameter at the junction of the arms.
At the beginning of each arm was a rubberized
flap, with a chamber containing chow at each
end (Figure 1A). Before the experiment began,
clues were sited around to make it easier for
rats to learn their surroundings. The
experiment was performed over three days, in
three stages, habituation, acquisition and
testing. In the habituation stage, two rats were
placed in the equipment at the same time. Rats
were allowed 10 min to familiarize themselves
with and become accustomed to the apparatus
and were able move around freely within the
maze. The rats were then fasted for 24 h. The
rats were placed in the apparatus 24 h later for
the acquisition stage. All arms were closed,
apart from one. Chow was placed in the open
arm and rats were placed in the apparatus one
by one. Rats were kept in the device for 10 min.
The test itself was performed on the third day.
In the test stage, all the arms were kept open.
Chow was placed in the same arm in which it
had been placed on the second day. Rats
entered the apparatus from the same location.
Time to entering the arm containing the chow
and number of times arms with no chow were
entered (error numbers) were recorded (Hao et
al., 2013). All data were recorded on camera.
After each procedure, the entire apparatus was
wiped down with 30 % alcohol to eliminate
scent clues.
Passive Avoidance Test
The passive avoidance test apparatus consisted
of two parts, light and dark areas. The light
section was 20 x 10 x 10 cm in size and the dark
section 20 x 20 x 20 cm. A rubberized flap 5 x 7
NeuroQuantology | December 2013 | Volume 11 | Issue 4 | Page 582-590
Odacı et al., Effects of 900 Megahertz EMF in the prenatal period on hippocampus and learning behavior
eISSN 1303-5150
www.neuroquantology.com
585
cm divided the two sections. The light section
was made of transparent material and was lit
with a 60 W light source located 60 cm above
the floor of the apparatus. The dark section was
made out of wood painted black and contains a
grill made out of stainless steel 2 x 3 cm in size
on the floor. The grill was connected via a cable
to an electroshock device capable of supplying
1.5 mA current (Figure 1B) (Yildirim et al.,
2013).
In the passive avoidance test, the aim
was to produce a sensation of fear through
administration of electroshock and for rats to
learn and remember what they learned. The test
was therefore performed in two days. On the
first day, acquisition of passive avoidance
behaviors (learning acquisition) and acquisition
latencies were measured. For that purpose, the
rats were first placed in the light area of the
apparatus with the dark section closed. The
rubberized flap to the dark section was opened
5 s later. We waited for rats to enter the dark
area and lengths of time to entry were recorded.
When rats entered the dark section, the flap was
closed and a 1.5 mA electroshock was
administered for 1.5 s. Rats were removed from
the dark area and replaced in the light section,
and the flap to the dark area was opened again.
Rats were allowed 120 s to enter the dark
section. Those that did not enter were regarded
as successful. The procedure was repeated with
those that did enter, and length of time to entry
was recorded. The recall test was performed 24
h later. Rats were placed in the light section in
the same apparatus. The rubberized flap of the
dark area was opened. Lengths of time from
passage from the light to the dark area
(avoidance latencies) were recorded. The test
was concluded for those rats that did not enter
the dark area within 300 s, and the avoidance
latency was recorded as 300 s. Lengths of time
to entry for those rats entering earlier were
recorded as avoidance latencies (Yildirim and
Marangoz, 2004; Yildirim et al., 2013).
Histological procedures and
histopathological examination
At the end of the study period (postnatal 32
st
day) (at the end of the learning, memory and
passive avoidance tests), all newborn female
rats were sacrificed on the same day by
decapitation under deep anesthesia (Ketalar 50
mg/kg). The brains were extracted and placed
in 10 % formaldehyde. After being kept in
formaldehyde for 1 week, brains were placed
under running tap water overnight. Brains were
fixed in paraffin for routine histological tissue
examinations. Brains embedded in paraffin
were sliced into 30-micron sections with the aid
of a microtome (Leica RM 2255, Leica
Instruments, Nussloch, Germany) and stained
with Cresyl violet. A research light microscope
(Olympus, BX51, Japan) was used for
histopathological examination of the stained
sections, and images were produced using an
Olympus DP 71 (Japan) camera microscope.
Figure 1. Radial arm maze test (A) and passive avoidance test
apparatus (B).
Statistical analyses
The nonparametric Mann–Whitney U test
(Tunc et al., 2007) was used to compare results
between the groups. Mean values are presented
with their standard error means (SEM).
Significance was set at p<0.05. All statistical
analyses were performed on SPSS software
(Statistical Package for the Social Sciences,
version 15.0, SSPS Inc., Chicago, IL, USA).
NeuroQuantology | December 2013 | Volume 11 | Issue 4 | Page 582-590
Odacı et al., Effects of 900 Megahertz EMF in the prenatal period on hippocampus and learning behavior
eISSN 1303-5150
www.neuroquantology.com
586
Results and Discussion
Behavioral test results
Animals’ eight arm radial maze test
performances were assessed under two
parameters; latency for finding the arm with the
chow placed in it beforehand (correct arm
selection), and number of incorrect choices
before finding the right arm. Mean latency for
finding the arm with chow left in it was 18±4 s
in NCG and 63±27 s in NEMFG. Mean number
of incorrect choices was 2.2±0.5 in NCG and
4.6±1.3 in NEMFG. Latency for finding the arm
with chow left in it beforehand was significantly
higher in NEMFG (p=0.007). Number of
incorrect choices was also higher in NEMFG
compared to NCG, though the difference was
not statistically significant (p=0.086) (Figure
2).
Figure 2. Radial arm maze test results from the newborn
control and newborn electromagnetic field (EMF) groups.
Statistical analysis revealed that newborn EMF group rats had a
significantly higher latency in terms of finding the maze arm
containing food (p=0.007), while the number of false selections
was not significant (p=0.086).
In the passive avoidance test, mean
acquisition latency before application of electric
shock was 12±4 s for NCG and 12±3 s for
NEMFG. Statistical analysis revealed no
significant difference between the groups.
Mean avoidance latency, recorded on the
second day of the test and regarded as the
primary finding in the learning of passive
avoidance behavior, was 262±26 s in NCG and
151±48 s in NEMFG. Avoidance latency was
significantly lower in NEMFG compared to
NCG (p=0.032) (Figure 3).
Figure 3. Passive avoidance test results from the newborn
control and newborn electromagnetic field (EMF) groups.
Statistical analysis revealed significantly lower avoidance
latency in the newborn EMF group rats than in newborn control
group (p=0.032).
Physical examination and
histopathological observation
Histopathological examination of the cornu
ammonis sections revealed no pathology in the
NCG (Figure 4 A, B and C). However, both
neuronal and morphological compromise was
determined in the NEMFG (Figure 4 D, E and
F). Physical examination revealed no skeletal
anomalies or unexpected findings in either
group.
Controversy still surrounds the potential
side-effects of EMFs emitted by mobile phones
on the human central nervous system
(Hietanen, 2006; Corle et al., 2012). However,
effects have been reported in animal brain
tissue morphology and physiological activities
NeuroQuantology | December 2013 | Volume 11 | Issue 4 | Page 582-590
Odacı et al., Effects of 900 Megahertz EMF in the prenatal period on hippocampus and learning behavior
eISSN 1303-5150
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587
(Salford et al., 2003; Odaci et al., 2008; Bas et
al., 2009a; 2009b; Maskey et al., 2010). One
particularly controversial suggestion is that the
use of mobile phones may be able to contribute
to malignant pathologies such as brain tumors
(Hardell et al., 1999; 2006; 2007) and
developmental anomalies (Bas et al., 2009a;
2009b; Sonmez et al., 2010). We therefore
think that this study will represent a significant
contribution to the literature. Our study
examined the cognitive functions of 32-day-old
female rats exposed during the prenatal term to
the effect of EMF emitted by mobile phones.
Behavioral tests were performed and the
hippocampuses were assessed
histopathologically. Negative effects on learning
and memory were determined in the NEMFG
rats in the radial arm maze and passive
avoidance tests. Additionally, neuronal and
morphological compromise was observed in the
EMF group. While both the behavioral and
morphological results bear similarities to
studies by some previous authors, they conflict
with those reported by others.
Figure 4. Histological views of the NCG (A, B and C), and NEMFG (D, E and F) groups. No distinct morphological difference can be
seen between the groups in images A and B for NCG, and D and E for NCG. Morphological differences in pyramidal cells can be seen
between the groups in the magnified equivalent views (image C for NCG and F for NCG). As described in the results section,
prenatal exposure to EMF led to compromise of the pyramidal cell in the NEMFG cornu ammonis (arrow) (F) compared with NCG
(arrow head) (C). NCG, newborn control group; NEMFG, newborn electromagnetic group; EMF, electromagnetic field; CA, cornu
ammonis; DG, dentate gyrus; V, ventricle, (Cresyl fast violet staining), (A and D, X 40; B and E, X 100; C and F, X 200).
Contradictory results have been
reported in studies examining the effect on
cognitive functions of the 900 MHz EMF
emitted by mobile phones. In one study, rats
exposed subchronically (SAR=1.5 W/kg, 45
min/day, 8 weeks) and chronically (SAR=6
W/kg, 15 min/day, 24 weeks) to 900 MHz EMF
from the head only were tested in a radial arm
maze apparatus. Neither application affected
spatial memory (Ammari et al., 2008). The
effect of EMF (900 MHz, 1 and 3.5 W/kg, 45
min) applied to the head only in rats was
examined using classic radial maze and open
field tests; no difference was determined
between the experimental and control groups in
terms of cognitive performance (Dubreuil et al.,
NeuroQuantology | December 2013 | Volume 11 | Issue 4 | Page 582-590
Odacı et al., Effects of 900 Megahertz EMF in the prenatal period on hippocampus and learning behavior
eISSN 1303-5150
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588
2002). In another study, adult male Wistar rats
were exposed to a GSM mobile telephone
(900/1800 MHz) in vibration mode for 3 weeks
(50 unanswered calls per day). The Morris
water maze test was used in that study, and
examination of rats’ spatial memory
performances revealed that exposure to mobile
phone resulted in memory compromise
(Narayanan et al., 2009). In another study rats
were exposed to 900 MHz EMF (0.6 and 60
mW/kg) for 2 h every week for 55 weeks. No
difference was determined in terms of
inquisitive behavior in the open field test, but
memory was impaired in rats exposed to EMF
in the episodic-like memory test (Nittby et al.,
2008). In our study, too, learning and memory
performances of rats exposed to 900 MHz on
prenatal days 13-21, every day for 1 h per day,
was seen to be compromised in the passive
avoidance and radial arm maze tests.
In one study in which Wistar rats were
exposed to low level EMF (17.5-75 mW/kg)
during pregnancy in order to investigate brain
development and the effect of EMF emitted by
mobile phones, prenatal exposure to EMF
resulted in no loss of cognitive performance
(Bornhausen and Scheingraber, 2000). In our
study, however, prenatal exposure
compromised both spatial memory and
learning. We think that the contradictory
findings from the two studies may be attributed
to methodological differences involving
intensity, duration and frequency of EMF
application. On the other hand, another study
applied mobile phone signals to young male
Wistar rats for 5 weeks (2 h/day, 5 days/week)
(mean SAR value=0.3 or 3.0 W/kg). Behavioral
analysis using the open field test, plus maze test
and acoustic startle response test determined
no significant difference between the groups.
Interestingly, however, learning and memory
increased significantly in the water maze test in
rats exposed to EMF (Kumlin et al., 2007). On
the basis of the findings, that study Kumlin et
al., (2007) concluded that mobile phone
radiation at the level to which humans are
exposed does not represent a threat to health.
Additionally, no degenerative changes involving
neuron death and permeability of the blood-
brain barrier were observed at morphological
examination in that study.
However, Kumlin et al.’s (2007) study
involves significant differences from both our
and other studies on the subject. Our
histopathological analysis revealed both
neuronal and morphological compromise in the
EMF group. Several previous studies have also
reported neuronal damage in the cortex,
cerebellum, hippocampus, and basal ganglia in
animals exposed to 900 MHz EMF (Mausset et
al., 2001; 2004; Salford et al., 2003). For
example, one study reported that 900 MHz
EMF can induce cell death, and that this can
inhibit differentiation of neuronal stem cells
into neurons in the embryonic period (Salford
et al., 2003). These studies naturally strengthen
the probability that the effect of the EMF
emitted by mobile phones can create
irreversible health problems, such as brain
tumor, in humans.
It has been suggested, at examination
of studies of the relation between mobile phone
use and brain cancer, that this probability, if it
exists, may be greater in children and young
people (Christ et al., 2010). One of the main
reasons for this is that children and young
people start using mobile phones for
communication at early ages, even though other
communication tools are available (Lenhart et
al., 2010). They will therefore be exposed to
greater effects of EMF during their lives.
Second, the skull and structures inside the skull
have not yet completed their morphological
development in childhood. For example, the
skull bone has not yet attained the thickness it
has in adulthood, and comparing an adult and a
child, the EMF emitted by mobile phones can
reach the brain and structures inside the brain
much easier through the child skull (Christ et
al., 2010). Another factor is that children and
young people are more interested in mobile
phones than adults. Lenhart et al., (2010)
reported that more than four out of five
children/teenagers aged 12 or more in America
sleep with a cell phone beside them, or often
under the pillow. They also reported that one in
three teenagers sends more than 100 text
messages a day, or 3000 texts a month. Such
calls represent a central function of mobile
phones for teenagers. Additionally, voice is the
primary mode of communicating with parents
for many teenagers (Lenhart et al., 2010).
Besides, Christ et al., (2010) compared the SAR
in various regions of the brain cortex for various
MRI-based head phantoms in adults and
children exposed to various makes of mobile
phone. They reported that children exposed to
mobile phone EMF of 1.800 MHz experience
greater exposures to such areas of the brain
cortical regions, the hippocampus and the
hypothalamus, as well as the eye, than adults.
They also reported that tissues such as the
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pineal gland exhibit no increase since the
distanced between them and mobile phones are
not age-dependent (Christ et al., 2010). Some
authors have therefore strongly advocated that
a change in brain tumors incidences in younger
age groups may ensue as exposure to cell
phones reaches long-term status and exceeds 10
years or longer (Christ et al., 2010; Corle et al.,
2012).
The results of an experimental animal
study cannot be applied directly to humans. In
the same way, developmental animal studies
cannot be directly compared with studies
involving human development. However,
animal study results should be compared with
those from the developmental stage in humans,
irrespective of whether testing takes place
during the fetal, prenatal, or postnatal periods
(Rodier, 1980; Jacobson, 1991; Odaci et al.,
2004). For example, the development of the rat
hippocampus in the prenatal period can be
compared with development of the
hippocampus in the third trimester in humans
(Dobbing, 1970; Dobbing and Sands, 1973;
Rodier, 1980; Jacobson, 1991). Therefore, the
results of this and previous studies of ours
(Odaci et al., 2008; Bas et al., 2009b) may be
interpreted as meaning that long-term (1 h per
day) mobile phone use in pregnancy can
damage the development of the hippocampus in
the human fetus. Since girls use mobile phones
more in general in comparison with males
(Lenhart et al., 2010), we used female rats in
the present study. It would therefore be more
accurate to interpret our study results as
meaning that mobile phone use in pregnancy
may affect hippocampus development in the
female fetus. Since most mobile phones operate
at a frequency of 900 MHz in Europe (Koyu et
al., 2005; Panagopoulos et al., 2007), we used
900 MHz EMF in our studies.
Conclusion and outlook
The purpose of this study was to investigate
how the effects of the 900 MHz EMF emitted by
mobile phones on the development of nervous
system structures in the prenatal period might
affect both behavior and hippocampus
morphology in the postnatal period. The
literature on the subject contains different
findings. We encountered no studies assessing
the behavior and hippocampus development of
female rat pups exposed to the effect of 900
MHz EMF on days 13-21 of pregnancy. We
therefore think that this study can add a new
dimension to the debate. Our results show that
exposure to a 900 MHz EMF in the prenatal
period had an adverse effect on female pups’
learning behavior and also caused
histopathological changes in the hippocampus.
The fact that rats’ learning behavior was
affected, in addition to the histopathological
changes seen in the hippocampus, suggests that
there may be an association between
pathological changes and behavior. However,
further electromicroscopic,
immunohistochemical and autoradiographic
studies are needed in order to reveal this
relationship. It should also be borne in mind
when planning these studies that our results
involve female rats.
About Authors
Ayşe İkinci, PhD student, PhD student of Histology and Embryology,
Dept. of Histology and Embryology, Karadeniz Technical University,
School of Medicine, Trabzon, Turkey. Ersan Odacı, MD, PhD, Professor
of Histology and Embryology, Dept. of Histology and Embryology,
Karadeniz Technical University, School of Medicine, Trabzon, Turkey.
Mehmet Yıldırım, PhD, Associate Professor of Physiology, Dept. of
Physiology, Karadeniz Technical University, School of Medicine,
Trabzon, Turkey. Haydar Kaya, PhD, Assistant Professor of Electrical
and Electronics Engineering, Dept. of Electrical and Electronics
Engineering, Karadeniz Technical University, School of Engineering,
Trabzon, Turkey. Metehan Akça, PhD student, PhD student of
Physiology, Dept. of Physiology, Karadeniz Technical University, School
of Medicine, Trabzon, Turkey. Hatice Hancı, PhD student, PhD student
of Histology and Embryology, Dept. of Histology and Embryology,
Karadeniz Technical University, School of Medicine, Trabzon, Turkey. Ali
Aslan, MD, PhD, Assistant Professor of Physiology, Dept. of Physiology,
Sakarya University, School of Medicine, Sakarya, Turkey. Osman Fikret
Sönmez,
MD,
Associate Professor of Neurosurgery, Dept. of
Neurosurgery, Samsun Education and Research Hospital, Samsun,
Turkey. Orhan Baş, PhD, Associate Professor of Anatomy, Dept. of
Anatomy, School of Medicine, Ordu University, Ordu, Turkey.
NeuroQuantology | December 2013 | Volume 11 | Issue 4 | Page 582-590
Odacı et al., Effects of 900 Megahertz EMF in the prenatal period on hippocampus and learning behavior
eISSN 1303-5150
www.neuroquantology.com
590
References
Aktürk Z, Odacı E, İkinci A, Baş O, Canpolat S, Çolakoğlu S, Sönmez
OF. Effect of Ginkgo biloba on brain volume after carotid artery
occlusion in rats: a stereological and histopathological study. Turk
J Med Sci DOI: 10.3906/sag-1305-40.
Ammari M, Jacquet A, Lecomte A, Sakly M, Abdelmelek H, de Seze R.
Effect of head-only sub-chronic and chronic exposure to 900-
MHz GSMelectromagnetic fields on spatial memory in rats. Brain
Inj 2008; 22(13-14): 1021-9.
Barcal J, Vozeh F. Effect of whole-body exposure to high-frequency
electromagnetic field on the brain cortical and hippocampal
activity in mouse experimental model. Neuroquantology 2007;
l5(3): 292-302.
Bas O, Odaci E, Kaplan S, Acer N, Ucok K, Colakoglu S. 900 MHz
electromagnetic field exposure affects qualitative and quantitative
features of hippocampal pyramidal cells in the adult female rat.
Brain Res 2009a; 1265: 178-85.
Bas O, Odaci E, Mollaoglu H, Ucok K, Kaplan S. Chronic prenatal
exposure to the 900 megahertz electromagnetic field induces
pyramidal cell loss in the hippocampus of newborn rats. Toxicol
Ind Health 2009b; 25(6): 377-84.
Bornhausen M, Scheingraber H. Prenatal exposure to 900 MHz, cell-
phone electromagnetic fields had no effect on operant-behavior
performances of adult rats. Bioelectromagnetics 2000; 21(8): 566-
74.
Christ A, Gosselin MC, Christopoulou M, Kuhn S, Kuster N. Age-
dependent tissue-specific exposure of cell phone users. Phys Med
Biol 2010; 55(7): 1767-1783.
Corle C, Makale M, Kesari S. Cell phones and glioma risk: a review of
the evidence. J Neurooncol 2012; 106(1): 1-13.
Dobbing J. Undernutrition and the developing brain: the relevance of
animal models to the human problem. Am J Dis Child 1970; 120:
411-415.
Dobbing J, Sands J. Quantitative growth and development of human
brain. Arch Dis Child 1973; 48: 757-767.
Dubreuil D, Jay T, Edeline JM. Does head-only exposure to GSM-900
electromagnetic fields affect the performance of rats in spatial
learning tasks? Behav Brain Res 2002; 129(1-2): 203-10.
Dubreuil D, Jay T, Edeline JM. Head-only exposure to GSM 900-MHz
electromagnetic fields does not alter rat’s memory in spatial and
non-spatial tasks. Behav Brain Res 2003; 145: 51-61.
Hancı H, Odacı E, Kaya H, Aliyazıcıoğlu Y, Turan I, Demir S,
Colakoğlu S. The effect of prenatal exposure to 900-MHz
electromagnetic field on the 21-old-day rat testicle. Reprod
Toxicol 2013;42C:203-209. doi: 10.1016/j.reprotox.2013.09.006.
Hardell L, Näsman A, Påhlson A, Hallquist A, Hansson Mild K. Use of
cellular telephones and the risk for brain tumours: a case-control
study. Int J Oncol 1999; 15(1); 113-116.
Hardell L, Carlberg M, Hansson Mild K. Pooled analysis of two case-
control studies on use of cellular and cordless telephones and the
risk for malignant brain tumours diagnosed in 1997–2003. Int
Arch Occup Environ Health 2006; 79(8): 630-9.
Hardell L, Carlberg M, Söderqvist F, Mild KH, Morgan LL. Long-term
use of cellular phones and brain tumours: increased risk
associated with use for Nor =10 years. Occup Environ Med 2007;
64(9): 626-32.
Hietanen M. Establishing the health risks of exposure to
radiofrequency fields requires multidisciplinary research. Scand J
Work Environ Health 2006; 32(3): 169-70.
Hao D, Yang L, Chen S, Tong J, Tian Y, Su B, Wu S, Zeng Y. Effects of
long-term electromagnetic field exposure on spatial learning and
memory in rats. Neurol Sci 2013; 34(2): 157-64.
İkinci A, Odacı E, Baş O. Effects of ethyl pyruvate administration on
female rats’ pyramidal cells of cornu ammonis after brain
ischemia: a stereological and histopathological study. Turk J Med
Sci 2013; 43(3): 354-361.
Jacobson M. Histogenesis and morphogenesis of cortical structures.
In: Jacobson, M (ed), Developmental Neurobiology. Third ed.
New York: Plenum Press 1991; 401-451.
Kaplan S, Odacı E, Canan S, Onger ME, Aslan H, Ünal B. The Disector
counting technique. Neuroquantology 2012a; 10: 44-53.
Kaplan S, Canan S, Altunkaynak ME, Odacı E, Aslan H, Unal B. An
unbiased way to estimate total quantities: the fractionator
technique. Neuroquantology 2012b; 10: 54-65.
Koyu A, Cesur G, Ozguner F, Akdogan M, Mollaoglu H, Ozen S. Effects
of 900 MHz electromagnetic field on TSH and thyroid hormones
in rats. Toxicol Lett 2005; 157(3): 257-62.
Kumlin T, Iivonen H, Miettinen P, Juvonen A, van Groen T, Puranen
L, Pitkäaho R, Juutilainen J, Tanila H. Mobile phone radiation
and the developing brain: behavioral and morphological effects in
juvenile rats. Radiat Res 2007; 168(4): 471-9.
Lenhart A, Ling R, Campbell SW, Purcell K. Teens and mobile phones.
A project of the Pew Research Center and the University of
Michigan. Available at http://www.pewinternet.org/
Reports/2010/Teens-and-Mobile-Phones.aspx
Maskey D, Kim M, Aryal B, Pradhan J, Choi IY, Park KS, Son T, Hong
SY, Kim SB, Kim HG, Kim MJ. Effect of 835 MHz radiofrequency
radiation exposure on calcium binding proteins in the
hippocampus of the mouse brain. Brain Res 2010; 1313: 232-41.
Mausset AL, de Seze R, Montpeyroux F, Privat A. Effects of
radiofrequency exposure on the GABAergic system in the rat
cerebellum: clues from semiquantitative immunohistochemistry.
Brain Res 2001; 912: 33-46.
Mausset AL, Hirbec H, Bonnefont X, Privat A, Vignon J, de Seze R.
Acute exposure to GSM 900-MHz electromagnetic fields induces
glial reactivity and biochemical modifications in the rat brain.
Neurobiol Dis 2004; 17: 445-454.
Narayanan SN, Kumar RS, Potu BK, Nayak S, Mailankot M. Spatial
memory performance of Wistar rats exposed to mobile phone.
Clinics (Sao Paulo) 2009; 64(3): 231-4.
Nittby H, Grafström G, Tian DP, Malmgren L, Brun A, Persson BR,
Salford LG, Eberhardt J. Cognitive impairment in rats after long-
term exposure to GSM-900 mobile phone radiation.
Bioelectromagnetics 2008; 29(3): 219-32.
Odaci E, Kaplan S, Sahin B, Bas O, Gevrek F, Aygun D, Unal B,
Sonmez OF, Colakoglu S, Bilgic S. Effects of low-dose
oxcarbazepine administration on developing cerebellum in
newborn rat: A stereological study. Neuroscience Research
Communications 2004; 34(1): 28-36.
Odaci E, Bas O, Kaplan S. Effects of prenatal exposure to a 900 MHz
electromagnetic field on the dentate gyrus of rats: a stereological
and histopathological study. Brain Res 2008; 1238: 224-9.
Panagopoulos DJ, Chavdoula ED, Nezis IP, Margaritis LH. Cell death
induced by GSM 900-MHz and DCS 1800-MHz mobile telephony
radiation. Mutat Res 2007; 626(1-2): 69-78.
Rodier PM. Chronology of neuron development: animal studies and
their clinical implications. Dev Med Child Neurol 1980; 22(4):
525-45.
Sakatani S, Okada YC, Hirose A. A quantitative evaluation of
dominant membrane potential in generation of magnetic field
using a pyramidal cell model at hippocampus CA3.
Neurocomputing 2002; 44: 153-160.
Salford LG, Brun AE, Eberhardt JL, Malmgren L, Persson BR. Nerve
cell damage in mammalian brain after exposure to microwaves
from GSM mobile phones. Environ Health Perspect 2003; 111:
881-883.
Savignac HM, Dinan TG, Cryan JF. Resistance to early-life stress in
mice: effects of genetic background and stress duration. Front
Behav Neurosci 2011; 5: 13.
Sienkiewicz ZJ, Blackwell RP, Haylock RG, Saunders RD, Cobb BL.
Low-level exposure to pulsed 900 MHz microwave radiation does
not cause deficits in the performance of a spatial learning task in
mice. Bioelectromagnetics 2000; 21(3): 151-8.
Sonmez OF, Odaci E, Bas O, Kaplan S. Purkinje cell number decreases
in the adult female rat cerebellum following exposure to 900 MHz
electromagnetic field. Brain Res 2010; 1356: 95-101.
Tunc AT, Aslan H, Turgut M, Ekici F, Odaci E, Kaplan S. Inhibitory
effect of pinealectomy on the development of cerebellar granule
cells in the chick: a stereological study. Brain Res 2007; 1138: 214-
220.
Yildirim M, Abidin I, Cansu A. Effects of chronic treatment with
commonly used antiepileptic drugs on passive avoidance learning
in prepubertal rats. J Exp Clin Med 2013; 30: 57-61.
Yildirim M, Marangoz C. Effects of nitric oxide on passive avoidance
learning in rats. Int J Neurosci 2004; 114(5): 597-606.
Weinstock M. Alterations induced by gestational stres in brain
morphology and behaviour of the offspring. Prog Neurobiol 2001;
65(5): 427-51.
Wigle DT, Arbuckle TE, Turner MC, Brub A, Yang Q, Liu S, Krewski D.
Epidemiologic Evidence of Relationships Between Reproductive
and Child Health Outcomes and Environmental. Chemical
Contaminants, Journal of Toxicology and Environmental Health,
Part B: Critical Reviews 2008; 11: 5-6, 373-517.
