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From: carter@gatech.CSNET (Carter Bullard)
Newsgroups: net.med
Subject: Nutrasweet(psychological problems?)
Message-ID: <617@gatech.CSNET>
Date: Tue, 23-Jul-85 19:46:33 EDT
Article-I.D.: gatech.617
Posted: Tue Jul 23 19:46:33 1985
Date-Received: Thu, 25-Jul-85 06:24:10 EDT
Reply-To: carter@gatech.UUCP (Carter Bullard)
Organization: School of ICS, Georgia Institute of Technology, Atlanta
Lines: 41
Summary: 

Well,
	  The effects of dietary phenylalanine in large quantities has been 
	  investigated to the point of absurdity since the early 60's, when
	  phenylketonuria was being heavily researched.  The documented
	  behavioral changes in rodents and humans appear to be quite dramatic,
	  in some cases causing symptoms similar to schizophrenia and/or
	  general psychosis.

	  This is of course not unexpected, since pheylalanine is the precursor
	  for two neurotransmitters, norepinephrine and dopamine.  Now dopamine
	  is very interesting, since it has been successfully argued as a 
	  principle agent in the development of several types of psychosis.
	  The greatest evidence that dopamine is involved in psychotic behavior 
	  is that most anti-psychotic drugs are very potent inhibitors of dopamine 
	  receptors.   This has been demonstrated with both classical and molecular
	  pharmacological techniques and is not disputed in the literature. 

	  In relation to aspartame, however, the problem is not simply that
	  one of its metabolites is pheylalanine, rather it is that a portion
	  of aspartame "looks" very similar to pheylalanine, and as a result
	  could have a tendency to enter the dopamine pathway itself, if it
	  can get into the brain without being metabolized.  The odds of this
	  happening are very good, since aspartame is rather cyclic and the
	  pheylalanine "part" is rather exposed, making it available for active
	  transport past the blood brain barrier and making the pheylalanine
	  "part" available for interaction with dopamine related receptor sites. 

	  Remember that when aspartame was being first developed, it was
	  described as a new amino acid derivative with unique properties.
	  Aspartame in actuality is a brand new amino acid, not ever seen
	  before in this universe.  It is difficult to predict how the CNS
	  will respond to a brand new amino acid that possesses unique 
	  properties as well as being physically similar to amino acids
	  that the brain is currently using for its normal function.

	  The problem that I have with all of this, then, is that the screening
	  process for new compounds does not include tests for psychological
	  effects, only tests for frank toxicity, teratogenic and carcinogenic
	  problems. 

	  Any comments?