Intraseptal microinjection of beta-funaltrexamine blocked a microwave-induced decrease of hippocampal cholinergic activity in the rat.

Lai H, Carino MA, Horita A. Guy AW

Pharmacol-Biochem-Behav. 1996 Mar. 53(3). P 613-6. 1996

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.