Related Experiment Video
Updated: Aug 8, 2026
Stereotactic Injection of MicroRNA-expressing Lentiviruses to the Mouse Hippocampus CA1 Region and Assessment of the Behavioral Outcome
Published on: June 10, 2013
Intraseptal microinjection of beta-funaltrexamine blocked a microwave-induced decrease of hippocampal cholinergic
1Department of Pharmacology, University of Washington, Seattle 98195, USA. hlai@u.washington.edu
Abstract:
Acute (45 min) exposure to pulsed (2 microseconds pulse width, 500 pulses per second) 2450-MHz microwaves at a power density of 1 mW/cm2 (whole body specific absorption rate 0.6 W/kg) microwaves caused a decrease in cholinergic activity in the hippocampus of the rat as measured by the sodium-dependent high-affinity choline uptake. Microinjection of beta-funaltrexamine (1 microgram) into the septum before microwave exposure blocked this effect. These data indicate that mu-opioid receptors in the septum mediate a microwave-induced decrease in cholinergic activity in the hippocampus and support our hypothesis that microwaves at a whole body SAR of 0.6 W/kg can activate endogenous opioids in the brain.
Insights
Microwave exposure decreased brain cholinergic activity via mu-opioid receptors in rats. This suggests that microwaves may activate the brain's natural opioid system.
Area of Science:
- Neuroscience
- Electromagnetic field effects
- Neuropharmacology
Background:
- Cholinergic activity in the hippocampus is crucial for memory and cognitive functions.
- Endogenous opioids play a role in modulating neuronal activity and pain perception.
- The effects of microwave exposure on brain neurochemistry are not fully understood.
Purpose of the Study:
- To investigate the impact of pulsed 2450-MHz microwave exposure on cholinergic activity in the rat hippocampus.
- To determine the role of mu-opioid receptors in mediating microwave-induced neurochemical changes.
- To explore the hypothesis that microwaves activate endogenous opioid systems in the brain.
Main Methods:
- Acute exposure of rats to pulsed microwaves (2 microseconds pulse width, 500 pulses/s) at 1 mW/cm2 (SAR 0.6 W/kg) for 45 minutes.
- Measurement of sodium-dependent high-affinity choline uptake in the hippocampus to assess cholinergic activity.
- Intraseptal microinjection of beta-funaltrexamine (a mu-opioid receptor antagonist) prior to microwave exposure.
Main Results:
- Microwave exposure significantly decreased cholinergic activity in the hippocampus.
- Pre-treatment with beta-funaltrexamine blocked the microwave-induced decrease in cholinergic activity.
- The findings indicate that mu-opioid receptors in the septum are involved in this effect.
Conclusions:
- Microwave exposure at a whole-body specific absorption rate of 0.6 W/kg can decrease hippocampal cholinergic activity.
- Mu-opioid receptors located in the septum mediate this microwave-induced neurochemical alteration.
- These results support the hypothesis that microwaves can activate endogenous opioid pathways in the brain.
