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Nearly 15% of all men and 30% of all women admit to a craving for chocolate.
Over 300 substances have been identified in chocolate. Some of these, including caffeine and theobromine (another, less powerful stimulant) could actually cause dependency effects. But the amounts of these substances in chocolate are too small to really have any effect.
The same goes for phenylethylamine, a substance related to a family of stimulants called amphetamines. For example, chocolate contains less phenylethylamine than goat cheese.
Anandamide, a neurotransmitter produced naturally by the brain, has also been isolated in chocolate. The neural receptors for anandamide are the same ones to which THC, the main active ingredient in cannabis, binds. The anandamide in chocolate might therefore contribute to the feeling of well-being reported by “chocoholics” (though you would have to eat well over 30 kilos of chocolate to experience effects comparable to one dose of cannabis!).
Be that as it may, many scientists agree that dependency on chocolate could simply be due to its taste, which causes a sensation of intense pleasure that people want to repeat.
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| HOW DRUGS AFFECT NEUROTRANSMITTERS |
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Dopamine appeared
very early in the course of evolution and is involved in many functions
that are essential for survival of the organism, such as motricity,
attentiveness, motivation, learning,
and memorization. But most of all, dopamine is a key element
in identifying natural rewards for the organism. These natural
stimuli such as food and water cause individuals to engage in approach
behaviours. Dopamine is also involved in unconscious memorization
of signs associated with these rewards.
It has now been established that all substances that trigger dependencies
in human beings increase the release of a neuromediator, dopamine,
in a specific area of the brain: the
nucleus accumbens. 
But not all drugs increase dopamine levels in the brain in the
same way.
- Some substances imitate natural
neuromediators and take their place on their receptors. Morphine,
for example, binds to the receptors for endorphin (a natural "morphine" produced
by the brain), while nicotine binds to the receptors for acetylcholine.
- Other substances increase the secretion of
natural neuromediators. Cocaine, for example, mainly increases
the amount of dopamine in the synapses, while ecstasy mainly
increases the amount of serotonin.
- Still other substances block a natural neuromediator.
Alcohol, for example, blocks the NMDA receptors.
Click on the names of each of the
following drugs to read about how they work and what effects
they have.
Alcohol ----- Opiates
(heroin, morphine, etc.) ----- Cocaïne ----- Nicotine
Caffeine ----- Amphetamines ----- Cannabis ----- Ecstasy ----- Benzodiazepines
Benzodiazepines
Benzodiazepines, such as diazepam
(Valium) and clonazepam (Rivotril) are anxiolytics that
can also have hypnotic or amnesia-inducing effects. Like
alcohol, these drugs increase the efficiency of synaptic
transmission of the neurotransmitter GABA by acting on
its receptors.
A GABA receptor is actually a macromolecular complex that,
in addition to containing sites for binding GABA, also
contains sites for binding other molecules such as benzodiazepines
that modulate GABA’s activity.
When benzodiazepines bind to a specific site on a GABA
receptor, they do not stimulate it directly. Instead, they
make it more efficient by increasing the frequency with
which the chlorine channel opens when GABA binds to its
own site on this receptor (see animation). The resulting
increase in the concentration of Cl- ions in the post-synaptic
neuron immediately hyperpolarizes this neuron, thus making
it less excitable.
Barbiturates bind to another site on the GABA receptor,
with similar effects. But the advantage of benzodiazepines
is that, unlike barbiturates, they do not open the Cl-
channels directly, but instead act more subtly by potentiating
the effect of GABA. Mixing benzodiazepines with alcohol
is still very dangerous, however, because their respective
effects on the Cl- channels can be additive.
We now know that benzodiazepines can cause a drug dependency
even in what are considered therapeutic doses, and even
in a short course of treatment.
General links about benzodiazepines:
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