Assessment of a combination of physostigmine and scopolamine as pretreatment against the behavioural effects of organophosphates in the common marmoset (Callithrix jacchus).
BACKGROUND
There is a requirement to ensure that UK armed forces are provided with the best possible medical countermeasures to prevent or mitigate the effects of exposure to nerve agents. When pretreatments are under consideration, it is of particular importance to ensure that they do not in themselves give rise to adverse effects and do not exacerbate the effects of agent exposure.


OBJECTIVE
The present study was designed to address these considerations for a combination of physostigmine and scopolamine as a potential pretreatment regimen.


METHODS
Common marmosets were trained to perform a two-choice discrimination serial reversal task, and baseline data were collected. Subjects received a dose of either soman or sarin after 2 weeks of pretreatment with either saline or physostigmine and scopolamine via miniosmotic pump.


RESULTS
No effects of physostigmine and scopolamine were seen on task accuracy or response rates. Neither accuracy of reversal performance nor number of responses made were significantly changed by administration of either soman or sarin subsequent to pretreatment with physostigmine/scopolamine. In the groups pretreated with saline, performance of the behavioural task, in terms of responses made, was virtually abolished on the day the OP was administered, but a significant increase in accuracy of performance was seen over the 2- to 14-day period following administration.


CONCLUSIONS
A combination of physostigmine and scopolamine, which is known to protect against nerve-agent lethality, offers protection against the effects of soman and sarin on behavioural performance, as measured by a discrimination reversal task. The improved performance observed following nerve agent requires further investigation.
Muggleton
N G
NG
Psychopharmacology Unit, School of Medical Sciences, University Walk, BS8 1TD, Bristol, UK. neil.muggleton@psy.ox.ac.uk
Bowditch
A P
AP
Crofts
H S
HS
Scott
E A M
EA
Pearce
P C
PC
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D002144:Callithrix; D002800:Cholinesterase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D004193:Discrimination Learning / Q000187:drug effects; D004343:Drug Implants; D004347:Drug Interactions; D005260:Female; D008297:Male; D018727:Muscarinic Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D009943:Organophosphorus Compounds / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D010830:Physostigmine / Q000008:administration & dosage / Q000494:pharmacology*; D012193:Reversal Learning / Q000187:drug effects; D012524:Sarin / Q000037:antagonists & inhibitors / Q000633:toxicity; D012601:Scopolamine / Q000008:administration & dosage / Q000494:pharmacology*; D012691:Serial Learning / Q000187:drug effects; D012999:Soman / Q000037:antagonists & inhibitors / Q000633:toxicity
D002800:Cholinesterase Inhibitors; D004343:Drug Implants; D018727:Muscarinic Antagonists; D009943:Organophosphorus Compounds; D012999:Soman; D010830:Physostigmine; D012524:Sarin; D012601:Scopolamine