Behavioral performance, brain histology, and EEG sequela after immediate combined atropine/diazepam treatment of soman-intoxicated rats.
It is known that rats poisoned with near-lethal doses of pinacolyl methylphosphonofluoridate (soman) develop brain lesions, particularly when convulsions are induced. When rats were intoxicated with a LD50 of soman and treated immediately thereafter with a combination of low doses of atropine and diazepam (LOW AS/DZ treatment), large decrements in performance of an earlier acquired shuttle-box task were found 6 days after intoxication. In contrast, no such decrements were found in soman-intoxicated animals treated similarly with a combination of high doses of these drugs (HIGH AS/DZ treatment). Surprisingly, surviving LOW AS/DZ animals acquired the same task again at a speed that was almost as fast as before intoxication. Similarly treated animals were examined light-microscopically 24 h after intoxication; in LOW-AS/DZ-treated animals, neuropathology was only observed in animals that had exhibited convulsions, whereas in HIGH AS/DZ animals neither convulsions nor brain damage were observed. Power spectra, obtained from electroencephalograms (EEGs) 6 days after intoxication, revealed significant differences between both treatment groups, particularly in the delta-, theta-, and beta-frequencies. After the HIGH AS/DZ treatment, a significant increase in delta activity was found compared to control values, suggestive of neuropathology. It is concluded that, in contrast with the LOW AS/DZ combination, HIGH AS/DZ prevents active avoidance deficits, convulsions, and light-microscopically detectable neuropathology after soman intoxication. However, the results of EEG measurements suggest that some aberrations may still remain even after the HIGH AS/DZ treatment.
Philippens
I H
IH
TNO Medical Biological Laboratory, Rijswijk, The Netherlands.
Melchers
B P
BP
de Groot
D M
DM
Wolthuis
O L
OL
D000818:Animals; D001285:Atropine / Q000627:therapeutic use*; D001362:Avoidance Learning / Q000187:drug effects; D001522:Behavior, Animal / Q000187:drug effects*; D001921:Brain / Q000473:pathology*; D003975:Diazepam / Q000627:therapeutic use*; D004569:Electroencephalography / Q000187:drug effects*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012640:Seizures / Q000503:physiopathology; D012999:Soman / Q000633:toxicity*
D001285:Atropine; D012999:Soman; D003975:Diazepam