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discovery of dopamine as a neurotransmitter

Alan J. Robinson robin073 at maroon.tc.umn.edu
Tue Nov 14 23:13:04 EST 1995

On 14 Nov 1995 05:08:46 GMT, 
cyble   <bmiller at scott.skidmore.edu> wrote:

>i'm afraid that i can't help on this one, but i have an additional 
>question: are levels of various neurotransmitters hereditary? in other 
>words, have there been any studies suggesting that normal/abnormal 
>levels of chemicals like dopamine and serotonin have a genetic basis? 
>i'm doing a paper on the hereditary nature of bipolar disorder and 
>schizophrenia, and i'm intrigued by this part.


Cloninger at Washington U., St. Louis, has developed a brain model for 
the Cluster B and C personality disorders which is based on the 
genetically determined variations in the activity of the brain 
monoaminergic pathways (dopamine, norepinephrine, and serotonin.)  
He has authored quite a few papers on this subject, starting about 
1985 and continuing to this day, which you can find in Medline.

An interesting sidelight to this research is that it was conducted to 
shed more light on the phenomenon of somatization - physical symptoms 
accompanying psychological ones.  It turns out that the cluster B 
personalities have this characteristic, which is associated with such 
personality traits as extroversion and social dominance.

The variation in monoamine levels is reflected as a variation in the 
levels of the enzyme(s) monoamine oxidase, which can be measured in 
blood platelets.   Even though there are no common polymorphisms for 
MAO, its level is controlled by at least 5 genetic loci.

Manic depression and schizophrenia have a substantial genetic basis, 
as shown by work on identical twins, but these diseases appear to 
involved some additional genes over and above those involved with 
the personality disorders.  MD and SCH also tend to have an onset in 
early adulthood, which points to some additional age related 
gene expression.  There is some connection between MD and personality, 
but SCH is much more enigmatic - unlike MD etc., a lot of the 
data still doesn't fit into any coherent picture of a disease process.


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