Effect of Low-Intensity Microwave Radiation on Monoamine Neurotransmitters and Their Key Regulating Enzymes in Rat Brain
Megha K, Deshmukh PS, Ravi AK, Tripathi AK, Abegaonkar MP, Banerjee BD. Effect of Low-Intensity Microwave Radiation on Monoamine Neurotransmitters and Their Key Regulating Enzymes in Rat Brain. Cell Biochem Biophys. 2015 Feb 12. [Epub ahead of print]
Abstract
The increasing use of wireless communication devices has raised major concerns towards deleterious effects of microwave radiation on human health. The aim of the study was to demonstrate the effect of low-intensity microwave radiation on levels of monoamine neurotransmitters and gene expression of their key regulating enzymes in brain of Fischer rats.
Animals were exposed to 900 MHz and 1800 MHz microwave radiation for 30 days (2 h/day, 5 days/week) with respective specific absorption rates as 5.953 × 10-4 and 5.835 × 10-4 W/kg. The levels of monoamine neurotransmitters viz. dopamine (DA), norepinephrine (NE), epinephrine (E) and serotonin (5-HT) were detected using LC-MS/MS in hippocampus of all experimental animals. In addition, mRNA expression of key regulating enzymes for these neurotransmitters viz. tyrosine hydroxylase (TH) (for DA, NE and E) and tryptophan hydroxylase (TPH1 and TPH2) (for serotonin) was also estimated.
Results showed significant reduction in levels of DA, NE, E and 5-HT in hippocampus of microwave-exposed animals in comparison with sham-exposed (control) animals. In addition, significant downregulation in mRNA expression of TH, TPH1 and TPH2 was also observed in microwave-exposed animals (p < 0.05).
In conclusion, the results indicate that low-intensity microwave radiation may cause learning and memory disturbances by altering levels of brain monoamine neurotransmitters at mRNA and protein levels.
Animals were exposed to 900 MHz and 1800 MHz microwave radiation for 30 days (2 h/day, 5 days/week) with respective specific absorption rates as 5.953 × 10-4 and 5.835 × 10-4 W/kg. The levels of monoamine neurotransmitters viz. dopamine (DA), norepinephrine (NE), epinephrine (E) and serotonin (5-HT) were detected using LC-MS/MS in hippocampus of all experimental animals. In addition, mRNA expression of key regulating enzymes for these neurotransmitters viz. tyrosine hydroxylase (TH) (for DA, NE and E) and tryptophan hydroxylase (TPH1 and TPH2) (for serotonin) was also estimated.
Results showed significant reduction in levels of DA, NE, E and 5-HT in hippocampus of microwave-exposed animals in comparison with sham-exposed (control) animals. In addition, significant downregulation in mRNA expression of TH, TPH1 and TPH2 was also observed in microwave-exposed animals (p < 0.05).
In conclusion, the results indicate that low-intensity microwave radiation may cause learning and memory disturbances by altering levels of brain monoamine neurotransmitters at mRNA and protein levels.
Excerpts
... Rats were exposed to microwave radiation at frequencies 900 and 1800 MHz and power level 1 mW for 30 days (2 h/day, 5 days/week) ... kept at a
distance of 100 cm from the source.
... Rats were exposed to microwave radiation at frequencies 900 and 1800 MHz and power level 1 mW for 30 days (2 h/day, 5 days/week) ... kept at a
distance of 100 cm from the source.
... Group I (sham exposed)—animals not irradiated to microwave radiation but kept under same conditions as that of other groups, Group II—animals irradiated at frequency of 900 MHz, SAR 5.953 9 10-4 W/kg and Group III—animals irradiated at frequency of 1800 MHz, SAR 5.835 9 10-4 W/kg ...
The results of present study indicate that low-intensity microwave radiation altered the levels of monoamine neurotransmitters viz. catecholamines (dopamine; DA,
norepinephrine; NE and epinephrine; E) and serotonin (5-HT) in hippocampus of experimental animals ...
A significant reduction in concentrations of DA (3.49 ± 0.24), NE (8.31 ± 0.51) and E (3.92 ± 0.22) (p\0.05, Fig. 3a (values expressed in lg/ml wet weight of tissue, mean ± SEM) was observed in hippocampus of 900 MHz-exposed animals in comparison with sham-exposed animals [5.14 ± 0.16 (DA), 11.95 ± 0.54 (NE), 5.89 ± 0.438 (E)] (Fig. 3a). Contrastingly, serotonin was not reduced significantly (4.99 ± 0.44) in animals exposed to 900 MHz microwave radiation when compared to sham-exposed animals (7.37 ± 1.05) as presented in Fig. 3b. Animals exposed to 1800 MHz microwave radiation showed significant decrease in levels of all neurotransmitters viz. DA (2.76 ± 0.35), NE (6.65 ± 0.44), E (3.16 ± 0.19) and also 5-HT (4.27 ± 0.31) (p<0 .05="" 1800="" 3="" 3a="" 5-ht="" 900="" among="" analysis="" and="" animals.="" as="" b.="" b="" br="" compared="" comparison="" concentrations="" da="" different="" e="" each="" fig.="" found="" group="" groups="" hoc="" ig.="" in="" indicated="" levels="" mhz="" ne="" not="" of="" other="" p="" post="" revealed="" sham-exposed="" significantly="" that="" were="" when="" whereas="" with="">
The results of gene expression analysis showed that low-intensity microwave exposure altered mRNA levels of enzymes [Tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH1 and TPH2)] involved in synthesis of catecholamines (DA, NE and E) and serotonin, respectively. Quantitative real-time PCR results revealed that expression level of TH mRNA showed a significant reduction in hippocampus of microwave-exposed animals (1.35-fold in 900 MHz animals and 1.83-fold in 1800 MHz group) in comparison with sham-exposed animals (p<0 .05="" br="">
Advancement in mobile phone technology and its extensive usage has brought serious attention towards possible adverse effects of microwave radiation on human health, in particular brain. A variety of neurological effects have been postulated including influence on synaptic plasticity, neurotransmitter release, neuronal survival, learning, and memory [17–20].
The first important finding of our study demonstrated that low-intensity microwave radiation exposure at 900 and 1800 MHz for 30 days induced significant reduction in levels of monoamine neurotransmitters (DA, NE, E and 5-HT) in hippocampus of experimental animals, substantiating that low-intensity microwave radiation might alter synthesis of these neurotransmitters, thereby leading to their reduced levels in brain. Since these biogenic amines play important role in learning and memory functions, the reduction in their levels can be strongly associated with learning and memory disturbances...
The second important finding of the study shows significant downregulation in mRNA expression of TH (rate-limiting enzyme in synthesis of catecholamines) in hippocampus of animals exposed to low-intensity microwave radiation (900 and 1800 MHz) for 30 days in comparison with sham-exposed animals. This decrease in mRNA expression of TH indicates reduced synthesis of enzyme THand can be strongly associated with reduced production of catecholamines viz. DA, NE and E. Similarly, mRNA expression of TPH1 and TPH2 (isoforms of TPH), rate-limiting enzymes in the synthesis of serotonin, was also decreased in response to low-intensity microwave exposure which indicates reduced synthesis of these enzymes and subsequently decreased serotonin synthesis in hippocampus.
Overall, the results of present study indicate that exposure to low-intensity microwave radiation induces alterations in brain monoamine neurotransmitters (play role in learning and memory functions) at mRNA and protein levels which might be the possible cause of cognitive dysfunction.
In conclusion, the results obtained in the present study provide strong evidence for extreme sensitivity of brain monoamine neurotransmitters to low-intensity microwave radiation. Thus, it is suggested that alterations caused in these neurotransmitters at mRNA and protein levels following low-intensity microwave exposure might be the possible cause for cognitive dysfunction. In view of these findings and to investigate other factors involved in cognitive dysfunction, further study is required.
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Joel M. Moskowitz, Ph.D., Director
Center for Family and Community Health
School of Public Health
University of California, Berkeley
Electromagnetic Radiation Safety
Website: http://www.saferemr.com
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