Medical/biological study (experimental study)

Effects of prenatal exposure to a 50-Hz magnetic field on one-trial passive avoidance learning in 1-day-old chicks med./bio.

By: Sun H, Che Y, Liu X, Zhou D, Miao Y, Ma Y

Published in: Bioelectromagnetics 2010; 31 (2): 150-155

Aim of study (acc. to author)

To study memory impairment in newly hatched chicks following in ovo exposure (i.e. egg exposure) to a 50 Hz magnetic field of 2 mT (60 min/day) on embryonic days 12-18.

Background/further details

Chick learning was compared in two experimental groups: isolated and paired chicks (these two groups are known to experience different stress levels). 295 chicks were divided into the following groups: 1) magnetic field exposure - isolated chicks, 2) magnetic field exposure - paired chicks, 3) sham exposure - isolated chicks, and 4) sham exposure - paired chicks. Within each group, chicks were randomly and further divided into one of three testing time sets of 10, 30, or 120 min (according to different stages of memory formation following hatching).

Endpoint

cognitive/behavioral endpoints: memory

Exposure

- 50/60 Hz
- magnetic field

Exposure	Parameters
Exposure 1: 50 Hz Exposure duration: 60 min/day on embyonic days 12 - 18	magnetic flux density: 2 mT

General information

chicks were divided into four groups: i) MF exposure - isolated ii) MF exposure - paired iii) sham exposure - isolated iv) sham exposure - paired

Exposure 1

Main characteristics

Frequency	50 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	60 min/day on embyonic days 12 - 18

Exposure setup

Exposure source	coil(s)
Setup	four sets of 250 turns of 1.68 mm copper wire wrapped horizontally around a 70 cm x 40 cm x 43 cm plastic frame; wooden box with eggs kept inside this coil
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	2 mT	-	measured	-	-

Reference articles

Bao X et al. (2006): A possible involvement of beta-endorphin, substance P, and serotonin in rat analgesia induced by extremely low frequency magnetic field

Exposed system:

animal
chicken embryos (eggs)

Methods Endpoint/measurement parameters/methodology

effects on embryo/fetus: hatching success, time of hatching, body weight, abnormalities
cognitive/behavioral endpoints: memory retention (passive avoidance test at 10, 30, and 120 min following administration of a bitter-tasting bead (methylanthranilate); number of pecks)

Investigated system:

investigation on living organism

Investigated organ system:

brain/CNS

Time of investigation:

after exposure

Main outcome of study (acc. to author)

The data demonstrated that magnetic field exposure in ovo during late incubation impaired young chick's memory in the passive avoidance test, depending on the stress level and the time of memory consolidation. Memory was intact at 10 minutes in both isolated and paired chicks with or without magnetic field exposure. However, magnetic field exposure did influence the performance of isolated chicks at 30 and 120 minutes, but not the performance of paired chicks.
With the exception of increased hatch weight in chicks exposed to magnetic field, there were no other obvious differences in hatching success, hatching time, and abnormalities.
The data suggest a potential disruption of memory formation following in ovo exposure to magnetic field, but this effect was only evident in the more stressed, isolated chicks.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

Chinese National Science Foundation
Chinese-Finnish International Collaboration Project NEURO
National Basic Research Program (Program 973), China
National High-tech R&D Program (863 Program), China
National Key Technologies R&D Program, China
Program of CASC

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