Biological Effects - RF/Microwave Interaction with Biological Tissues - page 117

3.7 INFLUENCE OF DRUGS

From data obtained at low-level microwave irradiation, it has been concluded
that endogenous opioids may play a mediating role in some of the neurological
effects of microwaves, summarized as follows [45]:

1. Microwaves enhance morphine-induced catalepsy in the rat.
2. Microwaves attenuate the naloxone-induced wet-dog shake, a morphine
withdrawal symptom, in morphine-dependent rats.
3. Narcotic antagonist blocks a transient increase in body temperature after
microwave exposure.
4. There is an effect of acute microwave exposure on amphetamine-
induced hyperthermia.
5. Microwave-induced changes in high-affinity choline uptake in the brain
can be blocked by narcotic antagonists.
6. Changes in concentrations of muscarinic cholinergic receptors in the
brain after repeated sessions of microwave exposure can be blocked by
pretreatment with narcotic antagonists before each session of microwave
exposure.
7. The three major subtypes of opioid receptor, m, d, and k, are involved in
the effect of microwaves on hippocampal high-affinity choline uptake.

Some research has been led under the assumption that the effects of
microwaves can be better understood while an animal is under the influence of
a drug. It was found that each brain region responds differently to microwaves
depending on exposure parameters. Effects on the frontal cortex are inde-
pendent of the exposure system and of the use of pulsed or CW microwaves.
The hippocampus responds to pulsed but not to CW microwaves. The response
of the striatal choligernic system depends on the exposure system used. Also,
under the same exposure conditions, different brain regions have different sen-
sitivities to microwaves. Hence the areas of the brain that show changes in
cholinergic activity are not correlated with localized SAR in the brain.
An important conclusion of investigations is that the long-term biological
consequences of repeated microwave exposure also depend on the parameters
of irradiation. Furthermore, some experiments showed that changes in cholin-
ergic receptors after repeated microwave exposure also depend on endoge-
nous opioids in the brain, as mentioned in Sections 3.2 and 3.5. The microwave
effects could be blocked by pretreatment, before each session of daily expo-
sure, with the narcotic antagonist naltrexone [83]. At present, there is no con-
vincing evidence that repeated exposure to low-level microwaves could lead
to irreversible neurological effects.
The action of drugs has already been mentioned in Section 3.6 relating to
effects on the eye. When the eye of a nonhuman primate was submitted to an