研究のタイプ: 医学/生物学の研究 (experimental study)

[ウィスター雌ラットの社会認知行動および嗅球のエストロゲン受容体発現に対する超低周波電磁界の9日間および30日間の反復ばく露の影響] med./bio.

Effects of repeated 9 and 30-day exposure to extremely low-frequency electromagnetic fields on social recognition behavior and estrogen receptors expression in olfactory bulb of Wistar female rats.

掲載誌: Neurol Res 2016: 165-175

この研究は、ウィスター雌ラットに60Hz電磁界EMFばく露を9日間または30日間、反復的に与え(ばく露パラメータは抄録には不記載)、ばく露終了後に社会認知行動テストを実施し、その後、嗅球でのエストロゲン受容体(α-およびβ- ER)発現免疫組織化学的測定した。実験には、無傷、卵巣切除(OVX)、卵巣切除+エストラジオール補充(OVX+E2)の3条件のラットを用いた。その結果、OVX群では、9日間のEMFばく露後に社会認知行動異常が見られたが、OVX+E2群では異常は見られず、30日ばく露でも同様であった;9日間のEMFばく露では、無傷ラット群でβ-ER発現が増加したが、他の群では増加が見られなかった;30日ばく露では、無傷ラット群でβ-ER発現が低下したが、他の群では増加した、と報告している。

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研究目的(著者による)

The effects of exposure of rats to a 60 Hz magnetic field on the social recognition behavior and expression of estrogen receptors in the olfactory bulb should be investigated.

詳細情報

The olfactory bulb plays a fundamental role in rat social recognition, e.g., of family members, and it is suggested that estrogen plays also an important role in social behavior. Studies demonstrated that mice lacking estrogen receptors showed modified social behavior. In a previous study (Reyes-Guerrero et al. 2006), the authors demonstrated that social recognition in ovariectomized rats was improved by estrogen supplement and exposure to an extremely low frequency magnetic field.
Female virgin rats were divided into the following groups (n=20 each): 1) exposure of intact rats to the magnetic field, 2) exposure of ovariectomized rats to the magnetic field, 3) exposure of ovariectomized rats supplemented with 17 β-estradiol (25 µg/kg daily, subcutaneous) to the magnetic field, 4) sham exposure of ovariectomized rats supplemented with estradiol, 5) sham exposure of ovariectomized rats, 6) sham exposure of intact rats. Each group was divided into 2 subgroups (n=10 each); one subgroup was exposed for 9 days, the other one for 30 days.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 60 Hz
ばく露時間: for 2 hours/day for 9 days
ばく露2: 60 Hz
ばく露時間: for 2 hours/day for 30 days

ばく露1

主たる特性
周波数 60 Hz
タイプ
  • magnetic field
ばく露時間 for 2 hours/day for 9 days
ばく露装置
ばく露の発生源/構造
ばく露装置の詳細 exposure system consisted of a chamber with a pair of circular double-wrapped Helmholtz coils, each made of 180 turns of 18-gage copper wire and with an internal diameter of 36 cm; coils were placed symmetrically one on each side of the experimental area (50 x 50 x 18 cm3) along the axis, separated by a distance equal to the radius of the coil and connected in parallel; field was uniform; experiments were performed at 22-23°C room temperature
Sham exposure A sham exposure was conducted.
Additional information sham-exposure followed the same protocol, but with the coils turned off
パラメータ
測定量 種別 Method Mass 備考
磁束密度 1 mT - 測定値 - -

ばく露2

主たる特性
周波数 60 Hz
タイプ
  • magnetic field
ばく露時間 for 2 hours/day for 30 days
ばく露装置
ばく露の発生源/構造
  • E1と同じ装置
Sham exposure A sham exposure was conducted.
パラメータ
測定量 種別 Method Mass 備考
磁束密度 1 mT - 測定値 - -

Reference articles

ばく露を受けた生物:

方法 影響評価項目/測定パラメータ/方法

研究対象とした生物試料:
研究対象とした臓器系:
  • 感覚器
調査の時期:
  • ばく露後

研究の主なアウトカム(著者による)

Social recognition was significantly impaired in ovariectomized rats exposed to the magnetic field (group 2) compared to intact sham exposed rats (group 6) after 9 and 30 days of exposure. This effect could be negated by supplement of 17 β-estradiol (group 3). After 30 days of exposure, also intact rats exposed to the magnetic field (group 1) showed significantly impaired social recognition compared to all groups without magnetic field exposure.
The authors state, that the protein expression data indicate that the amount of α- and β-estradiol receptors may be modified by exposure to the magnetic field and that this modification in the receptors correlates with changes in the olfactory behavior. However, no significant effect of the magnetic field alone on the protein expression of estrogen receptors can be seen. (remark EMF-Portal: results and conclusions are not consistent and not comprehensive with respect to the figures.)
The authors conclude that exposure of rats to a 60 Hz magnetic field might alter social recognition behavior. Supplement of estrogens might protect from this effect and could increase the expression of estrogen receptors in the olfactory bulb, which might play a role in olfactory memory.

研究の種別:

研究助成

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