Study On The Preventive Effect Of Huperzine A Against Nerve Agents Attack

Objective: Most of nerve agents are organophosphate compounds, which irreversiblyinhibit peripheral and central acetylcholinesterase (AChE), was highly toxic and not easyto detect. They were used by terrorist and also used as chemical agents in regional conflictsSo studies about them were emphasized, but there were no any ideal prophylaxis foragainst the nerve agents so far. Huperzine A(9-amino-13-ethylidene-11-methyl-4-azatricyclo [7.3.1.0(3.8)] trideca-3(8), 6, 11-trien-5-one) is a lycopodium alkaloid isolatedfrom the moss Huperzia serrate. Huperzine A acts as a potent, highly specific andreversible inhibitor of acetyl cholinesterase. May be it can be used as the effectiveprophylaxis against nerve agents. There were no any reports about Huperzine A againstnerve agents. Our objective was to study the basic feature of Huperzine A inhibiting theactivity of acetylcholine esterase and collect data for screening the ideal dose of HuperzineA to prevent against nerve agent attack, and study the preventive effect of Huperzine A andselect the ideal dose of Huperzine A being used to against nerve agents attack, and comparewith Pyridostigmine bromide.Methods: This study was divided into four parts. According WS/T 67—1996, wemodified the method of Acetylthiocholine-Dithio—bis—nitrobenzoic acid (ASCH-DTNB)determining acetylcholine esterase activity and the standard curve using this modifiedmethod was established in first part. The second part was to study the basic feature ofHuperzine A inhibiting the activity of acetylcholine esterase. The dose of 0.2, 0.5, 0.7, 1.0,1.5, 2.0, 3.0, 5.0, 10.0mg/kg of Huperzine A was used to study the dose-effect relationshipon inhibition of cholinesterase activity of whole blood, frontal cortex, cerebellum,hippocampus in rats. The dose of 2.0mg/kg Huperzine A was used to study the time-effectrelationship on inhibition of rat cholinesterase activity 0.5, 1, 2, 4, 8, 12, 24 hours after exposure. The third part was to study the preventive effect of Huperzine A against nerveagents and select the ideal dose of Huperzine A being used to against nerve agents attack,we used Paraoxon as nerve agent, Paraoxon only treated group (2.7mg/kg) was regarded asthe control and the 0.5,1.0,2.0,5.0mg/kg of Huperzine A combined Paraoxon(2.7mg/kg) asthe treatment group. The mortality, death time, score of SLUD and IM were comparedamong all experimental groups. Paraoxon treated group (3.6mg/kg) was used as thecontrol and the 0.5,1.0,2.0,3.0mg/kg of Huperzine A combined Paroxon(3.6mg/kg) used asthe treatment group. The mortality, death time were compared among all experimentalgroups. In the fourth parts, we compared the preventive effect of Huperzine A andPyridostigmine against nerve agent attack, the dose of 1.0mg/kg Huperzine A and5.82mg/kg Pyridostigmine bromide were used to against nerve agent attack before2.7mg/kg Paraoxon was administered, the mortality, score of SLUD and IM were recordedand compared with the control group.Result: The inhibition of cholinesterase activity reaches the peak after 0.5 hour andretrieved after 24 hours. The inhibition on cholinesterase activity obtained by the dose of0.5-3.0 mg/kg of Huperzine-A was the ideal inhibition ratio for using Huperzine A againstnerve agent attack; After given 1.0mg/kg huperzine A, score of SLUD and IM of the treatment groupof 1.0mgH+2.7mgP were low than control group after Paraoxon exposure 0.5h or 1.0h, the mortalityis 14.28%. The difference between this group and control group showed statistically significant (P＜0.05).The average death time of the treatment group of 1.0mgH+3.6mgP is (22.75±13.69) min, Thedifference between this group and control group showed statistically significant (P＜0.05); After given1.0mg/kg huperzine A or 5.82mg/kg Pyridostigmine bromide, the mortality of Huperzine A andPyridostigmine treatment group were 10.00% and 15.00%, the mortality of control group was 54.54%,score of SLUD and IM of the treatment group were low than control group, the difference betweentreatment group and control group showed statistically significant (P＜0.05), no significant differencebetween two treatment group was found (P＞0.05).Conclusions: Huperzine A was a reversible, long effective cholinesterase inhibitor, itcan breakthrough the blood brain barrier, and it was an effective prophylaxis against nerve agents, 1.0mg/kg of Huperzine A is the ideal dose for nerve agents prevention in rats, andits preventive efficiency was equal to Pyridostigmine bromide.