Abstract:
Microwave (MW) radiation induced oxidative stress reduces dendritic arborization, spine density and number of
hippocampal pyramidal neurons and hence, impair learning and spatial memory through p53-dependent/independent
apoptosis of hippocampal neuronal and nonneuronal cells. However, the mechanisms responsible for MW radiation
induced impairment in memory formation remains still unknown. This study elucidates the effect of short (15 days) and
long-term (30 and 60 days) low level 2.45 GHz MW radiation-induced local stress on the hippocampal spatial memory
formation pathway in adult male mice. Twelve-weeks old mice were exposed to 2.45 GHz MW radiation (continuous-wave
with overall average Power density of 0.0248 mW/cm2 and overall average whole body SAR value of 0.0146 W/Kg) @ 2 h/d for
15, 30, and 60 days. Learning and spatial memory was assessed by 8-arm radial maze. We have investigated the alterations
in serum corticosterone level and the expression of glucocorticoid receptor, corticotropin-releasing hormone (CRH),
inducible nitric oxide synthase (i-NOS), iGluRs, PSD-95-neuronal NOS (n-NOS) system, protein kinase A, protein kinase CeERK1/2-pERK1/2 in all the hippocampal subregions, viz. CA1, CA2, CA3, and DG through immunohistochemistry/
immunofluorescence and alterations in the expression of hippocampal glucocorticoid receptor, CRH-receptor 1 (CRH-R1),
cAMP-response element-binding (CREB), and phosphorylated-CREB (p-CREB) through western blot analysis. We observed
that 2.45 GHz MW irradiated mice showed slow learning and significantly increased number of working and reference
memory errors in radial maze task. Further, 2.45 GHz MW radiation exposure increases serum corticosterone level and the
expression of CRH, CRH-R1, and i-NOS, while the expression of iGluRs, n-NOS, PSD-95, protein kinase Ce, protein kinase A,
ERK-p-ERK, CREB, and p-CREB decreases in above mentioned hippocampal subregions in a duration dependent manner.
Our findings led us to conclude that 2.45 GHz MW radiation exposure induced local stress suppresses signaling
mechanism(s) of hippocampal memory formation
