The Science of Heroin
There are three important brain chemicals--neurotransmitters--that
relate to heroin: dopamine, norepinephrin, and the endorphins.
Dopamine
Dopamine helps to control human appetites for both food and
sex. Large amounts of this substance are also associated
with being out-going and exuberant. Parkinson's Disease and
depression are related to having too little dopamine in the
brain whereas schizophrenia is related to having too much.
Heroin, like pretty much all drugs that get a person high,
causes a release of dopamine.
Norepinephrin
Norepinephrin governs the sympathetic nervous system--the
nerves of the body that cannot be voluntarily controlled.
It's primary purpose is to stabilize blood pressure so that
it does not get too low. When a provocative situation arises,
the brain's release of this substance stimulates the
fight or flight response. Heroin depresses the middle
brain--the locus coeruleus, in particular--and so provides
the user with the opposite feelings: safety and contentment.
Opioid Receptors
There are sites in the body--primarily in the brain and spinal
cord--called opioid receptors which are involved in happiness
and feelings of safety. These sites were originally discovered
by scientists searching for mechanisms that allowed morphine
to cause pleasure and relieve pain. All of the opioids attach
to these sites where their effects are felt. There are at least
five different kinds of opioid receptors but only four that
are closely associated with the effects of the opioids: mu,
kappa, delta, and sigma. The mu and kappa sites affect pain
relief, the delta sites are involved with feelings of euphoria,
and the sigma sites relieve depression.
Endorphines
It makes sense that the body would not have these receptors
unless it created its own chemicals which would fit into
these sites and before long, scientists had discovered
endorphins--morphine-like chemicals used by the body for
many purposes but primarily to modulate mood, promote pleasure,
and manage reactions to stress.
The way that morphine differs from the natural endorphins--and
there is some indication that the body creates its own morphine,
not just morphine-like substances--is that it is possible
to bombard the receptors with it whereas under most circumstances,
the body only produces a small amount of endorphins at any
time.
by Dr. H © 2000
Taken from Little Book of Heroin,
Ronin Publishing, Inc.
Last Modified: 14 January 2004
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