>Nancy asked:
>" .......a student has asked for an explanation of how hallucinogens act on
>the brain at the cellular level, and how that is different from how
>addictive drugs act on brain cells...."
> and Ed Pollak replied,
>
>The short answer seems to be that most hallucinogens act at serotonergic
>receptors but there's conflicting evidence as to whether the major effects
>are agonistic or antagonistic. Most addictive drugs seem to directly (e.g.,
>cocaine) or indirectly (e.g., heroin) act as dopaminergic agonists. But of
>course it's much more complicated than this. Your student needs to get a
>good psychopharmacology or physiol. psych book if he/she wants more detail.
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
As Ed indicated, it really is more complicated than that. There are
serotonergic hallucinogens or psychedelics (e.g. LSD), Norepinephrine
(noradrenergic) hallucinogens (e.g., mescaline or peyote), and Cholinergic
hallucinogens (e.g., muscarine, physostigmine). There are also psychedelic
anesthetics (e.g phencyclidine, ketamine). I believe folks are still not
sure what receptors or transmitters are involved with the latter. Then
there is marijuana, often misclassified as a hallucinogen, which appears to
bind to the same receptors (in many areas of the brain) as the recently
discovered endogenous substance, anandamide. The term "addictive drugs"
really depends on how you are defining addiction. Nevertheless, while
cocaine acts to block catecholamine reuptake and is thus a
catecholaminergic agonist (as are the amphetamines, which promote
catecholamine release as well as reuptake), the opiates appear to bind to
opiate receptors and mimic the enkephalins. The bottom line is that similar
behaviors can be produced via a variety of different mechanisms at the
cellular level.
George Goedel
Professor & Chairperson
department of Psychology
Northern Kentucky University
Highland Hts., KY 41099-2000
[EMAIL PROTECTED]
