Three groups of rats were examined (n=6 per group): 1.) sham exposure, 2.) 900 MHz microwave exposure and 3.) 1800 MHz microwave exposure.
The enzyme tyrosine hydroxylase catalyzes the reaction to form a precursor for dopamine, which, in turn, is a precursor for the neurotransmitters norepinephrine and epinephrine. Tryptophan hydroxylase is an enzyme involved in the synthesis of the neurotransmitter serotonin.
|Exposure duration||2 hours per day, 5 days per week|
|Distance between exposed object and exposure source||100 cm|
|Chamber||rats were restrained in closed boxes (L: 30 cm x B: 15 cm x H: 20 cm), provided with holes of 1 cm diameter for ventilation and were kept at a distance of 100 cm from the source|
|Setup||GTEM cell was a pyramidal tapered, dual-terminated section (L: 220 cm x B: 120 cm x H: 80 cm); microwave source consisted of a signal generator operating at a frequency range of 9 kHz to 3.2 GHz, an amplifier, a DC regulator and a power meter; microwave chamber was lined with absorbers to minimize reflections|
|Sham exposure||A sham exposure was conducted.|
The levels of the neurotransmitters dopamine, norepinephrine, epinephrine were significantly decreased in exposed rats (900 MHz and 1800 MHz) compared to sham exposed rats. The level of serotonin was also decreased in the exposed groups when compared to the sham exposure, but only significantly in the group exposed to the 1800 MHz microwaves. Additionally, in both exposure groups the gene expression of the enzymes tyrosine hydroxylase and tryptophan hydroxylase was significantly decreased in comparison to the sham exposed animals.
The authors conclude that exposure to low-intensity microwaves influences monoamine neurotransmitter levels and their key regulating enzymes in the brain of rats.