TY - JOUR
T1 - Natural killer cell activity reduced by microwave exposure during pregnancy is mediated by opioid systems
AU - Nakamura, Hiroyuki
AU - Seto, Toshio
AU - Hatta, Kotaro
AU - Matsuzaki, Ichiyo
AU - Nagase, Hirofumi
AU - Yoshida, Masami
AU - Ogino, Keiki
N1 - Funding Information:
1This work was supported in part by Grant-in Aid for Scienti®c Research (C; No. 07670431, C; No. 09670382) from Ministry of Education, Science, and Cultures of Japan for 1995—1998. All animal studies were conducted in accordance with national and international guidelines for the protection of animal welfare, as stated under Materials and Methods.
PY - 1998/11
Y1 - 1998/11
N2 - We have previously demonstrated immunosuppression including reduced splenic natural killer cell activity (NKCA) in pregnant rats exposed to microwaves produced mainly by their thermal action. To examine the involvement of opioid systems in reduced NKCA in pregnant rats exposed to microwaves at a relatively low level (2 mW/cm2 incident power density at 2450 MHz for 90 min), we assayed β-endorphin (βEP) in blood, pituitary lobes, and placenta as well as splenic NKCA in virgin and/or pregnant rats. Although microwaves elevated colonic temperatures by 0.8°C for virgin and 0.9°C for pregnant rats, and βEP in blood and anterior pituitary lobes (ALP) significantly, it did not change blood corticosterone as an index of hypothalamic-pituitary adrenal axis. There were significant interactions between pregnancy and microwave exposure on splenic NKCA, βEP in both blood and AP, and blood progesterone. Intraperitoneal administration of opioid receptor antagonist naloxone prior to microwave exposure increased NKCA, blood, and placental βEP in pregnant rats. Alterations in splenic NKCA, βEP and progesterone in pregnant rats exposed to microwaves may be due to both thermal and nonthermal actions. These results suggest that NKCA reduced by microwaves during pregnancy is mediated by the pituitary opioid system.
AB - We have previously demonstrated immunosuppression including reduced splenic natural killer cell activity (NKCA) in pregnant rats exposed to microwaves produced mainly by their thermal action. To examine the involvement of opioid systems in reduced NKCA in pregnant rats exposed to microwaves at a relatively low level (2 mW/cm2 incident power density at 2450 MHz for 90 min), we assayed β-endorphin (βEP) in blood, pituitary lobes, and placenta as well as splenic NKCA in virgin and/or pregnant rats. Although microwaves elevated colonic temperatures by 0.8°C for virgin and 0.9°C for pregnant rats, and βEP in blood and anterior pituitary lobes (ALP) significantly, it did not change blood corticosterone as an index of hypothalamic-pituitary adrenal axis. There were significant interactions between pregnancy and microwave exposure on splenic NKCA, βEP in both blood and AP, and blood progesterone. Intraperitoneal administration of opioid receptor antagonist naloxone prior to microwave exposure increased NKCA, blood, and placental βEP in pregnant rats. Alterations in splenic NKCA, βEP and progesterone in pregnant rats exposed to microwaves may be due to both thermal and nonthermal actions. These results suggest that NKCA reduced by microwaves during pregnancy is mediated by the pituitary opioid system.
KW - Immunosuppression
KW - Naloxone
KW - Pitutary
KW - Placenta
KW - β-endorphin
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U2 - 10.1006/enrs.1998.3866
DO - 10.1006/enrs.1998.3866
M3 - Article
C2 - 9841809
AN - SCOPUS:0031744224
VL - 79
SP - 106
EP - 113
JO - Environmental Research
JF - Environmental Research
SN - 0013-9351
IS - 2
ER -