Evidence for Effects on Neurology and Behavior - BioInitiative Report

oxidase inhibitors, but was not significantly affected by serotonin [Lobanova, 1974a]. Some of
these results can be explained by the pharmacological properties of the drug tested. Pentobarbital
and chloral hydrate are hypnotic agents and are known to have anticonvulsant effects.
Chlorpromazine, nicotine, and monoamine oxidase inhibitors can lower the seizure threshold or
induce convulsions depending on their dosages. Atropine, a cholinergic antagonist, has been
shown to enhance the seizure threshold. It is puzzling that bemegride decreased RFR induced
seizures, since it is a nervous system stimulant with similar pharmacological actions as the
convulsant pentylenetetrazol.
Exposure to pulsed RFR (7 and 20 mW/cm 2 ) was reported to affect the effects of the
convulsants, pentylenetetrazol and strychnine, on EEG activity [Baranski and Edelwejn, 1974].
Another study showed that low-level RFR altered the sensitivity of animals to the seizure
inducing effect of pentylenetetrazol [Servantie et al., 1974]. Rats and mice were subjected to 8-
36 days of pulsed RFR (3000 MHz, 0.9-1.2 s pulses, 525 pps, 5 mW/cm 2 ). No significant
change in susceptibility to the drug was seen after eight days of exposure; however, a decrease
in susceptibility was observed after 15 days, and an increase in susceptibility was observed after
20, 27, and 36 days of irradiation. Mice became more susceptible to the convulsive effect of
pentylenetetrazol and more animals died from convulsions. Thus, the sensitivity of the nervous
system to the convulsive action of the drug changed as a function of the duration of exposure. In
another study, Pappas et al. [1983] showed in the rat that acute (30 min) exposure to 2700-MHz
pulsed RFR at 5, 10, 15, and 20 mW/cm 2 (SARs 0.75, 1.5, 2.25, and 3.0 W/kg, respectively)
produced no significant interaction effect on pentylenetetrazol induced seizure or the efficacy of
chlordiazepoxide (an anticonvulsant) to block the seizure.
Drugs affecting cholinergic functions in the nervous system have also been studied.
Chronic RFR-exposed rats (10-15 days) were found to be less susceptible to the paralytic effect
of curare-like drugs, which block nicotinic cholinergic transmission. A similar effect was
observed on muscle preparations from the irradiated rats. Presumably, the cholinergic
transmission in the neuromuscular junction was affected by RFR. Ashani et al. [1980] reported
that acute pulsed RFR (10 min, 10 mW/cm 2 ) enhanced the hypothermic effects of an inhibitor of
AChE (the degradation enzyme of acetylcholine). The site of this effect was determined to be
located inside the central nervous system. Monahan [1988] also reported that RFR (2450 MHz,
continuous-wave, whole body SARs 0.5-2.0 W/kg) affected the actions of scopolamine, a
cholinergic antagonist, and physostigmine, a cholinergic agonist, on motor activity of mice in a
maze. The data suggested enhancement of cholinergic activity after RFR irradiation.
Several studies investigated the actions of benzodiazepines, a group of drugs used <strong>for</strong>
anticonvulsion, sedation-hypnosis, and antianxiety purposes. Two of the most commonly used
benzodiazepines <strong>for</strong> the treatment of anxiety disorders are chlordiazepoxide (Librium) and
diazepam (Valium). Low-level pulsed RFR (1 mW/cm 2 , whole body SAR 0.2 W/kg)
potentiated the effect of chlordiazepoxide on bar-pressing behavior of rats working on a DRLschedule
<strong>for</strong> food rein<strong>for</strong>cement; however, the same authors also reported no interaction effects
between RFR and diazepam on bar pressing [Thomas et al., 1979, 1980].
Increase in brain benzodiazepine receptors in the brain after RFR exposure [Lai et al,
1992a] could explain the <strong>for</strong>mer effect. A possible explanation <strong>for</strong> the discrepancy of the results
observed with chlordiazepoxide and diazepam was that diazepam has a higher potency than
chlordiazepoxide. The potency of diazepam that was effective in attenuation of experimental
conflict, an animal model of anxiety, was about four times that of chlordiazepoxide [Lippa et al.,
1978], and the in vitro relative affinity of diazepam with benzodiazepine receptors was 30-65
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