A Review of Microwave Irradiation and Actions of Psychoactive Drugs

H. Lai irradiation on the action of barbiturates. Mice exposed to A. Horita continuous-wave (CW) 2450 MHz microwaves at 25 to 50 C. K. Chou mW/cm2 showed a dose (power density)-dependent reducA. W. Guy tion in the duration of hexobarbital anesthesia [5]. The effect University of Washington School of Medicine was claimed to be unrelated to stress, as plasma corticosterone level was lower in the irradiated animals than in the controls. Baranski and Edelwejn [61 reported that acute S IMILARITIES exist between microwave irradiation and pulsed microwave irradiation (20 mW/cm2) had little effect drugs with regard to their actions on biological systems. In on the EEG pattern of rabbits given phenobarbital. However, both cases, certain effects follow their absorption into the in chronically exposed animals (7 mW/cm2, 200 h), desynbodies of test animals. Power density and specific absorption chronization of the EEG pattern was seen after phenobarbital rate (SAR) of microwave irradiation are analogous to the administration, whereas synchronization was seen in the concentration of the injection solution and the dosage of drug controls [7]. However, Benson, et al. [81 demonstrated administration, respectively. Conceivably, SAR would be the decreased onset-time and prolonged duration of phenobarbimore pertinent indicator of the resulting effect; similar to the tal-narcosis in mice after irradiation with microwaves (CW, dose-response relationship of drug action, the effect of 10 mW/cm2, 10 min). These effects were caused by an microwave irradiation should be proportional to the SAR. increase in deposition of phenobarbital in the brain. Rabbits Furthermore, analogous to drug effects, the effect of microanesthetized with pentobarbital and then subjected to 5 min waves should be the sum of specific (direct) and nonspecific of microwave irradiation (CW, 0.7 to 2.8 mW/cm2) showed (indirect) effects on the physiological process being studied. periods of alternating EEG arousal and sedation and periods of A further corollary is that consequences similar to those of behavioral excitation [9]. The duration of arousal seemed to drug treatment, e.g., tolerance, sensitization, conditioning to correlate with the power density of the irradiation. Wangeenvironmental cues, and so forth, could occur after micromann and Cleary [10] have also reported that short-term wave irradiation. microwave irradiation (CW, 5-50 mW/cm2) decreased the However, additional properties of microwaves complicate duration of sodium pentobarbital-induced loss of righting this simplistic interpretation. First, in contrast to the relatively reflex in the rabbit. The investigators suggested that this homogeneous distribution of drugs in the body, microwaves effect could be related to the thermal effect of microwaves, have complex absorption patterns that depend on the paramwhich led to a decreased distribution of pentobarbital to the eters of the radiation. For example, differences in absorption central nervous system. Indeed, Bruce-Wolfe and Justesen rate are found even inregions of the brain only millimeters [11] have recently reported that warming an animal with apart [11. Different patterns of energy deposition could lead microwaves during anesthesia can attenuate the effects of to different effects and failure to replicate an effect observed pentobarbital. In a series of recent experiments we in another exposure condition. However, a dose (SAR)[Swearengen, Lai & Horita: Abst. Neurosci. Sci., 12:896, response relationship should be apparent when an effect is 19861 studied the effects of body temperature on pentobarbistudied in animals irradiated under the same exposure condital-narcosis. Hypothermia was prevented in pentobarbitaltions. A second consideration is doubt as to whether microinjected rats by warming with a heat lamp, which maintained waves have specific effects on body functions. The existence the colonic temperature at approximately 38°C. Such treatof specific microwave receptors, similar to drug receptors, is ment did not significantly affect pentobarbital-narcosis, as not likely. Thus, the major effect of microwaves could be judged by the duration of loss of righting reflex, as well as the nonspecific, e.g., as a consequence of changes in tissue concentration of pentobarbital in the brain. Thus, it is temperature, calcium efflux, etc. However, it is also possible interesting that micrQwaves could attenuate the narcoleptic that certain features of microwaves can trigger specific effects of pentobarbital [9-11]. Perhaps this effect of microneural responses; for instance, pulsed microwaves can affect waves is not caused by a generalized thermal effect but is the auditory system [21 and activate specific neural pathdependent on the localized pattern of heating in the body ways, and thermal effect on skin sensors could trigger a caused by the irradiation. specific pattern of thermoregulatory responses. These speWe exposed rats to 2450 MHz pulsed microwaves at 1 cific and nonspecific effects of microwaves can alter the mW/cm2 (2 As, 500 pps, whole-body average SAR 0.6 W/ functions of the nervous system and, in turn, modify the kg), which did not significantly affect the colonic temperature actions of psychoactive drugs. The objective of this paper is of the rat after 45 min of exposure. Effects of pentobarbital to review the research on the effects of microwave irradiation were studied after the exposure, and we found that microon the actions of psychoactive drugs, and to discuss the waves prolonged the narcolepsy and hypothermia induced by implications of the data regarding brain functions. the drug [12]. Interestingly, we also found that exposure of rats in two different orientations in our circular waveguide MICROWAVES AND THE ACTIONS OF (facing towards or away from the source) had different PSYCHOACTIVE DRUGS effects on the pentobarbital-induced hypothermia. In our In iew of the reported effects of low-level microwave exposure system the average whole bodySARs are similar in irradiation on brain functions and its complex effects on the two orientations of exposure, whereas localized absorpbehavior [3, 41, it is conceivable that microwave irradiation tion patterns are different [11. These data suggest that could also affect the action of psychoactive drugs. However, localized SARs are important considerations in determining little work has been done in this area, especially on the the effects of microwaves>.. effects of low-level microwaves (< 1 mW/cm 2). Drugs Affecting the Thermal Effect of Microwaves Barbiturates Studies on the effects of drugs on thermal responses to Several studies have investigated the effects of microwave microwaves have recently been reviewed by Jaucham [13].