A series of experiments was carried out to study whether pretreatment with the cholinergic agonist physostigmine or the opiate antagonist naltrexone could reverse this behavioral effect of microwave exposure. In addition, since the origin (peripheral or central) of the endogenous opioid effect was not known, the effect of pretreatment with the peripheral opiate antagonist naloxone methiodide was also studied. If the behavioral effect involves only endogenous opioids inside the CNS, treatment with naloxone methiodide would have no significant effect on the spatial memory deficit.
|Pulse width||2 µs|
|Packets per second||500|
|Chamber||circular waveguide with circularly polarized TE11 mode field; Each tube containing a plastic chamber to house a rat|
|Additional info||Source of exposure: described in Guy et al.  Guy AW. Wallace J. McDougall JA (1979).|
After exposure the rats showed retarded learning while performing in the radial-arm maze to obtain food rewards (food was situated at the end of each arm), indicating a deficit in spatial working memory function. This behavioral deficit was reversed by pretreatment before radiation with the cholinergic agonist physostigmine or the opiate antagonist naltrexone. The pretreatment with the peripheral opiate antagonist naloxone methiodide showed no reversal of effect. The results indicate that both cholinergic and endogenous opioid neurotransmitter systems in the brain are involved in the microwave-induced spatial memory deficit.