Xref: utzoo sci.bio:836 sci.med:3884
Path: utzoo!mnetor!uunet!nbires!hao!husc6!spdcc!dyer
From: dyer@spdcc.COM (Steve Dyer)
Newsgroups: sci.bio,sci.med
Subject: Re: Acetylcholine source needed...
Message-ID: <573@spdcc.COM>
Date: 18 Jan 88 02:38:21 GMT
References: <506@dl901b.engin.umich.edu> <560@spdcc.COM> <1559@aecom.YU.EDU>
Organization: S.P. Dyer Computer Consulting, Cambridge MA
Lines: 25

In article <1559@aecom.YU.EDU>, werner@aecom.YU.EDU (Craig Werner) writes:
> 	Two other "drugs" that increase acetylcholine in the nervous
> system are Malathion and Parathion, which are not used as drugs, but
> rather as industrial insecticides.  However, as far as increasing
> Acetylcholine levels, they are quite "efficient," probably the most
> efficient in general use.

Actually, malathion is a relatively "inefficient" cholinesterase inhibitor
for most birds and mammals, including humans.  One of its sulfur atoms must be
enzymatically replaced by an oxygen atom to "activate" it.  Before this
happens, mammalian decarboxylases detoxify the compound into an inactive
metabolite which has no effect on cholinesterase.  Insects also "activate"
the compound, but they have no detoxification pathway, hence malathion's
relative selectivity for insects over mammals and birds.  It is possible
to overwhelm the detoxification pathway, but it takes a LOT of malathion.
Malathion is also poorly (10%) absorbed through the skin.  This is why you
will find malathion in use as a topical ectoparasiticide and advertised as
a common garden insecticide, whereas parathion is limited to agricultural use,
necessitates impermeable clothing and a respirator, and has been implicated
in more poisonings and deaths than any other insecticide.

-- 
Steve Dyer
dyer@harvard.harvard.edu
dyer@spdcc.COM aka {ihnp4,harvard,husc6,linus,ima,bbn,m2c}!spdcc!dyer