title: Low-level microwave irradiation and central cholinergic systems.
abstract: Our previous research showed that 45 min of exposure to low-level, pulsed microwaves (2450-MHz, 2-microseconds pulses, 500 pps, whole-body average specific absorption rate 0.6 W/kg) decreased sodium-dependent high-affinity choline uptake in the frontal cortex and hippocampus of the rat. The effects of microwaves on central cholinergic systems were further investigated in this study. Increases in choline uptake activity in the frontal cortex, hippocampus, and hypothalamus were observed after 20 min of acute microwave exposure, and tolerance to the effect of microwaves developed in the hypothalamus, but not in the frontal cortex and hippocampus, of rats subjected to ten daily 20-min exposure sessions. Furthermore, the effects of acute microwave irradiation on central choline uptake could be blocked by pretreating the animals before exposure with the narcotic antagonist naltrexone. In another series of experiments, rats were exposed to microwaves in ten daily sessions of either 20 or 45 min, and muscarinic cholinergic receptors in different regions of the brain were studied by 3H-QNB binding assay. Decreases in concentration of receptors occurred in the frontal cortex and hippocampus of rats subjected to ten 20-min microwave exposure sessions, whereas increase in receptor concentration occurred in the hippocampus of animals exposed to ten 45-min sessions. This study also investigated the effects of microwave exposure on learning in the radial-arm maze. Rats were trained in the maze to obtain food reinforcements immediately after 20 or 45 min of microwave exposure.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Pharmacology, University of Washington School of Medicine, Seattle 98195.
authors.forename: H
authors.initials: H
authors.lastname: Lai
authors.forename: M A
authors.initials: MA
authors.lastname: Carino
authors.forename: A
authors.initials: A
authors.lastname: Horita
authors.forename: A W
authors.initials: AW
authors.lastname: Guy
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism / Q000528:radiation effects; D002794:Choline / Q000378:metabolism; D007858:Learning / Q000528:radiation effects; D008297:Male; D008872:Microwaves; D009292:Narcotic Antagonists / Q000494:pharmacology; D009622:Noise; D010275:Parasympathetic Nervous System / Q000528:radiation effects*; D011813:Quinuclidinyl Benzilate; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000187:drug effects; D012149:Restraint, Physical; D012964:Sodium / Q000502:physiology; D013315:Stress, Psychological / Q000503:physiopathology / Q000523:psychology; D013997:Time Factors; D014916:Whole-Body Irradiation
chemical_list: D009292:Narcotic Antagonists; D011976:Receptors, Muscarinic; D011813:Quinuclidinyl Benzilate; D012964:Sodium; D002794:Choline