Maternal linalool treatment protects against radiofrequency wave-induced deteriorations in adolescent rats: A behavioral and electrophysiological study.

The prenatal period is a critical phase of brain development. During this time, the brain is highly susceptible to stress factors, such as RF radiation from mobile phones. Numerous studies indicate that mobile phone radiation can cause anxiety, cognitive impairment, disturbances in calcium homeostasis, and increased permeability of the blood–brain barrier. The blood–cerebrospinal fluid barrier and the cerebrospinal fluid–brain barrier regulate trace element balance in the brain via complex mechanisms. Copper (Cu), manganese (Mn), iron (Fe), and zinc (Zn) are essential for physiological function and brain development. These elements, among other things, regulate gene expression, act as enzyme activators, and protect against the formation of reactive oxygen species (ROS). Disrupting the homeostasis of these trace elements can lead to neurodegenerative diseases such as Alzheimer's or Parkinson's disease. Linalool, a monoterpene found in essential oils, is used in naturopathy. It is said to have antioxidant, anti-inflammatory, and anxiolytic properties. This study investigates the effects of intrauterine mobile phone exposure on adolescent rats and the potential protective effects of linalool.

Twenty pregnant female rats were randomly divided into four groups of five rats each (n = 5): 1. Control Group (saline); 2. Linalool Group (25 mg/kg linalool); 3. Exposed Group (RF radiation exposure + saline); and 4. Exposed + Linalool Group (RF radiation exposure + 25 mg/kg linalool). The exposure source was a commercial 900 MHz GSM mobile phone (Nokia 1616) with the following manufacturer specifications: SAR value 1.19 W/kg (head) and 0.32 W/kg (whole body). The daily exposure duration during the entire gestation period (21 days) was 1 hour and 40 minutes. Mobile phone radiation was generated by 100 missed calls per day, with the phone placed 20 cm from the cages. Three to five offspring per mother were placed in sex-separated cohorts (n = 10) for subsequent analysis. Behavioral tests (elevated plus maze, Morris water maze, and light-dark box) were performed on day 50 after birth. Electrophysiological tests were performed on brain neurons on day 60 after birth. We examined the excitability of hippocampal neurons using an input/output protocol and long-term potentiation with 100 Hz stimulation of Schaffer collaterals. Next, we quantified the trace elements copper (Cu), manganese (Mn), iron (Fe), and zinc (Zn) in the hippocampus. Statistical analyses were performed using ANOVA with the appropriate post hoc tests. All examinations were performed on a gender-specific basis.

In neurobehavioral tests, offspring exposed prenatally (Group 3) exhibited statistically significant differences compared to the control group (Group 1). Both male and female animals exhibited anxiety-like behaviors, as well as impaired spatial learning and memory. The female animals were more severely affected than the males. Maternal linalool treatment greatly reduced the harmful effects of mobile phone radiation exposure, often bringing them down to the level of the unexposed control group. Electrophysiological examinations revealed significantly reduced excitability of hippocampal neurons, accompanied by impaired induction and maintenance of long-term potentiation, in Group 3 compared to Group 1. No sex-based differences were observed. Once again, maternal administration of linalool led to significant improvements in electrophysiological findings, bringing them to the level of the control group. The homeostasis of the examined trace elements in the hippocampus was disturbed in a statistically significant manner: Fe, Cu, and Mn increased significantly, while Zn decreased significantly. With the exception of Zn, maternal linalool treatment restored homeostasis. This also significantly improved the Cu/Zn ratio.

In a rat model, prenatal exposure to a commercial mobile phone can cause substantial and persistent damage in both sexes. This damage includes impaired neuronal excitability and synaptic plasticity, both of which are associated with altered behavior and cognitive performance. The authors suggest that oxidative stress or increased blood–brain barrier permeability is responsible for altered trace element homeostasis. The Cu/Zn ratio is an indicator of inflammation and oxidative stress. According to the authors, the documented neuroprotective effect of linalool may be related to its antioxidant properties or its ability to increase synaptic plasticity.

Editor’s note:

The multimodal design of the study, which includes neurobehavioral, electrophysiological, and biochemical analyses, as well as gender-specific data, yields robust results. Earlier studies in various species have confirmed the observed harmful effects of mobile phone radiation [1–3]. Although dosimetric verification of the RF radiation level was not performed because the RF radiation was generated by a commercial mobile phone that falls below international limits, this is a realistic exposure scenario. Due to the simplicity of the exposure parameters, the study can be easily reproduced. (RH)

1. Deniz ÖG, Kaplan S (2022). The effects of different herbals on the rat hippocampus exposed to electromagnetic field for one hour during the prenatal period. Journal of Chemical Neuroanatomy, 119, 102043. https://doi.org/10.1016/j.jchemneu.2021.102043

2. Qin TZ, Wang X, Du JZ, Lin JJ, Xue YZ, Guo L et al. (2024). Effects of radiofrequency field from 5G communications on the spatial memory and emotionality in mice. International Journal of Environmental Health Research, 34(1), 316–327. https://doi.org/10.1080/09603123.2022.2149708

3. Dasgupta S, Wang G, Simonich MT, Zhang T, Truong L, Liu H et al. (2020). Impacts of high dose 3.5 GHz cellphone radiofrequency on zebrafish embryonic development. PLOS One, 15(7), e0235869. https://doi.org/10.1371/journal.pone.0235869