Effect of microwave radiation on adult neurogenesis and behavior of prenatally exposed rats.

Accumulating evidence suggests that neurogenesis persists in the adult mammalian brain. New neurons arise in two main regions: the subventricular zone (SVZ) of the lateral ventricles, followed by migration along the rostral migratory stream (RMS), and the subgranular zone (SGZ) of the dentate gyrus (DG), which is part of the hippocampus. Adult neurogenesis is essential for cognitive and emotional functions, and disruptions in these processes have been linked to neurodegenerative disorders. Among the various signaling molecules involved, nitric oxide (NO), a free radical, plays a particularly important role in regulating adult neurogenesis. Previous studies by this research group revealed that radiofrequency electromagnetic fields can adversely affect neurogenesis in the olfactory regions of rats. The current study aims to determine the influence of prenatal exposure to a pulsed 2.45 GHz microwave field on postnatal neuronal proliferation, neuronal death, and nitrergic neuron populations, and behavior in rat offspring.

Pregnant Wistar rats were exposed daily for two hours to a pulsed 2.45 GHz electromagnetic field (power density 28 W/m²; whole-body SAR = 1.73 W/kg) within shielded chambers throughout gestation. Control rats underwent identical sham exposure procedures. Their offspring (n = 12) were evaluated at two developmental stages: juveniles at five weeks of age and adults at three months of age. For both age groups, neurogenic regions were assessed through a combination of immunohistochemical and histochemical techniques. Specifically, Ki-67 immunolabeling was used to quantify proliferating cells, and Fluoro-Jade C staining identified dying cells in the RMS and DG. In parallel, NADPH-diaphorase histochemistry enabled the quantitative analysis of nitrergic (NO-releasing) neurons, revealing both cell counts and morphological features. In addition, adult offspring underwent blinded behavioral assessments, comprising the Open Field Test, Elevated Plus Maze, and Light–Dark Box, to evaluate anxiety-like behavior and locomotor activity.

Exposure to Wi-Fi radiation during gestation produced significant alterations in neurogenesis-related markers in both juvenile and adult rats, though the direction of the changes varied by age. In juveniles, a pronounced increase in proliferative cells was observed in both the RMS, particularly in the "elbow" subregion, and the DG. This proliferation was accompanied by a significant increase in cell death within the RMS. In addition, the number of nitrergic neurons in the RMS decreased markedly, and surviving cells exhibited immature morphology, indicating delayed neuronal differentiation. In contrast, adult rats that had been exposed prenatally showed a significant decrease in cell proliferation in both the RMS and DG compared to sham-exposed controls. Apoptosis in the RMS remained elevated, while cell death in the DG showed no significant difference. Similar to the juveniles, the number of nitrergic neurons in the RMS decreased, and cellular morphology suggested developmental delay. Behaviorally, adult rats exhibited signs of reduced anxiety and hyperactivity, a phenotype that paralleled the histological findings and suggested an ADHD-like profile.

The data indicate that prenatal exposure to pulsed 2.45 GHz Wi-Fi radiation produces long-lasting disruptions in postnatal neurogenesis. In the RMS, this manifests as a biphasic pattern: an initial proliferative surge in juveniles, followed by a decline in proliferative capacity in adults. This decline is accompanied by persistently elevated neuronal death in both stages. Alterations in nitrergic neuron populations, characterized by decreased cell numbers and delayed maturation, further underscore the disturbed maturation of NO-releasing neurons. According to the authors, the emergence of hyperactivity and reduced anxiety-like behavior in adult rats suggests functional consequences that parallel ADHD-like phenotypes in humans. Although extrapolation to human neurodevelopment requires caution, these findings highlight the potential impact of ubiquitous radiofrequency exposure on critical developmental processes in the central nervous system.

Editor's note:

The strength of this study lies in its rigorous dosimetric validation (pulsed 2.45 GHz, SAR < 2 W/kg, two hours per day) alongside the use of sham controls and the comprehensive, blinded analyses. These analyses included histological markers of proliferation, cell death, and nitrergic neuron populations, as well as behavioral assays. By examining both juvenile and adult offspring, the authors reveal developmental stage-dependent, biphasic responses to prenatal microwave exposure. Balanced sex distribution across groups minimizes the likelihood of gender-related confounders. Nevertheless, the direct analogy drawn between the observed hyperactivity and human ADHD remains speculative. (RH)