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1. Drug Therapy and Drug Abuse
• There are more than 100 known neurotransmitters.
• The most widely studied neurotransmitters to date are acetylcholine,
norepinephrine, dopamine, serotonin, and gamma-aminobutyric acid
(GABA). Acetylcholine is an essential CNS neurotransmitter for memory
circuits in the limbic system.
• Norepinephrine is important to dreaming, waking, and mood. The
neurotransmitter dopamine plays a central role in the brain’s regulation of
mood. Dopamine is also the basal nuclei neurotransmitter that helps
organize coordinated movements.
• Serotonin is involved in thermoregulation, sleeping, emotions, and
perception.
• GABA is an abundant inhibitory neurotransmitter in the CNS.

2. • Neuromodulators are naturally occurring molecules that block the
release of a neurotransmitter or modify a neuron’s response to a
neurotransmitter.
• Two well-known neuromodulators are substance P and endorphins.
• Substance P is a neuropeptide that is released by sensory neurons
when pain is present.
• Endorphins block the release of substance P and serve as natural
painkillers. Endorphins are produced by the brain during times of
physical and/or emotional stress. They are associated with the
“runner’s high” of joggers.

4. Both pharmaceuticals and illegal drugs have
several basic modes of action:
• They promote the action of a neurotransmitter, usually by increasing
the amount of neurotransmitter at a synapse. Examples include drugs
such as alprazolam (Xanax) and diazepam (Valium), which increase
GABA. These medications are used for panic attacks and anxiety.
• Reduced levels of norepinephrine and serotonin are linked to
depression. Drugs such as fluoxetine (Prozac), paroxetine (Paxil), and
duloxetine ( Cymbalta) allow norepinephrine and/or serotonin to
accumulate at the synapse, which explains their effectiveness as
antidepressants.

5. • They interfere with or decrease the action of a neurotransmitter. For
instance, antipsychotic drugs used for the treatment of schizophrenia
decrease the activity of dopamine. The caffeine in coffee, chocolate,
and tea keeps us awake by interfering with the effects of inhibitory
neurotransmitters in the brain.
• They replace or mimic a neurotransmitter or neuromodulator. The
opiates—namely, codeine, heroin, and morphine—bind to endorphin
receptors and in this way reduce pain and produce a feeling of well-
being.

6. Drug Abuse
• Drug abuse is apparent when a person takes a drug at a dose level
and under circumstances that increase the potential for a harmful
effect.

7. Alcohol
• With the exception of caffeine, alcohol (ethanol) consumption is the
most socially accepted form of drug use in the United States.
• Alcohol acts as a depressant on many parts of the brain by increasing
the action of GABA, an inhibitory neurotransmitter.
• Depending on the amount consumed, the effects of alcohol on the
brain can lead to a feeling of relaxation, lowered inhibitions, impaired
concentration and coordination, slurred speech, and vomiting.

9. Nicotine
• When tobacco is smoked or chewed, nicotine is rapidly delivered
throughout the body. It causes a release of epinephrine from the
adrenal glands, increasing blood sugar and causing the initial feeling
of stimulation.
• As blood sugar falls, depression and fatigue set in, causing the user to
seek more nicotine.
• In the CNS, nicotine stimulates neurons to release dopamine, a
neurotransmitter that promotes a temporary sense of pleasure, and
reinforces dependence on the drug. About 70% of people who try
smoking become addicted.

11. Cocaine and Crack
• Cocaine is an alkaloid derived from the shrub Erythroxylon coca.
• Approximately 35 million Americans have used cocaine by sniffing/
snorting, injecting, or smoking.
• Cocaine is a powerful stimulant in the CNS that interferes with the
reuptake of dopamine at synapses, increasing overall brain activity.
The result is a rush of a sense of well-being that lasts from 5 to 30
minutes. However, long-term use of cocaine causes a loss of
metabolic functions in the brain

13. • Cocaine is highly addictive; with continued use, the brain makes less
dopamine to compensate for a seemingly endless supply.
• The user experiences withdrawal symptoms and an intense craving
for cocaine.
• Overdosing on cocaine can cause cardiac and/or respiratory arrest

14. Crack
• Crack” is the street name given to cocaine that is processed to a free-
base form for smoking. The term crack refers to the crackling sound
heard when the drug is smoked. Smoking allows high doses of the
drug to reach the brain rapidly, providing an intense and immediate
high, or “rush.” Approximately 8 million Americans use crack.

15. Methamphetamine and Ecstasy
• Methamphetamine and ecstasy are considered club, or party, drugs.
Methamphetamine (commonly called meth or crank) is a powerful CNS
stimulant.
• Meth is often produced in makeshift home laboratories, usually starting
with ephedrine or pseudoephedrine, common ingredients in many cold
and asthma medicines. As a result, many states have passed laws making
these medications more difficult to purchase.
• The structure of methamphetamine is similar to that of dopamine, and the
most immediate effect of taking meth is a rush of euphoria, energy,
alertness, and elevated mood.
• Chronic use can result in what is called an amphetamine psychosis,
characterized by paranoia, hallucinations, irritability, and aggressive, erratic
behavior.

17. Ecstasy
• Ecstasy is the street name for MDMA
(methylenedioxymethamphetamine), which is chemically similar to
methamphetamine.
• Many users say that “X,” taken as a pill that looks like an aspirin or
candy, increases their feelings of well-being and love for other people.
• However, it has many of the same side effects as other stimulants,
plus it can interfere with temperature regulation, leading to
hyperthermia, high blood pressure,and seizures.

18. Heroin
• Heroin is derived from the resin or sap of
the opium poppy plant, which is widely
grown in a region from Turkey to Southeast
Asia and in parts of Latin America.
• Drugs derived from opium are called
opiates, a class that also includes morphine
and codeine.
• After heroin is injected, snorted, or smoked,
a feeling of euphoria, along with relief of
any pain, occurs within a few minutes.

19. • As with other drugs of abuse, addiction is common. Heroin binds to
receptors meant for the endorphins, naturally occurring
neurotransmitters that kill pain and produce feelings of tranquility.
• With repeated heroin use, the body’s production of endorphins
decreases.
• Tolerance develops, so the user needs to take more of the drug just to
prevent withdrawal symptoms (tremors, restlessness, cramps,
vomiting), and the original euphoria is no longer felt.

22. • Heroin addiction can be treated with synthetic opiate compounds,
such as methadone or buprenorphine and naloxone ( Suboxone), that
decrease withdrawal symptoms and block heroin’s effects. However,
methadone itself can be addictive, and methadone related deaths are
on the rise.

23. Marijuana and K2
• The dried flowering tops, leaves, and stems of the marijuana plant,
Cannabis sativa, contain and are covered by a resin that is rich in THC
(tetrahydrocannabinol).
• The names cannabis and marijuana apply to either the plant or THC.
Marijuana can be ingested, but usually it is smoked in a cigarette
called a “joint.”

24. • Researchers have found that THC binds to a receptor for anandamide,
a naturally occurring neurotransmitter that is important for short-
term memory processing, and perhaps for feelings of contentment.
• The occasional marijuana user experiences mild euphoria, along with
alterations in vision and judgment. Heavy use can cause
hallucinations, anxiety, depression, paranoia, and psychotic
symptoms.
• Research is under way to identify the effects of long-term marijuana
use on the brain, as well as on the effects ofsecond hand marijuana
smoke on the respiratory system.

26. K2
• In recent years, awareness has been increasing about a synthetic
compound called K2, or spice. Originally synthesized by an organic
chemist at Clemson University, K2 is about ten times as potent as
THC.
• The chemical is typically sprayed onto a mixture of other herbal
products and smoked. However, because there is no regulation of
how it is produced, the amount of K2 itself, or contaminants, can vary
greatly. This may account for the several reports of seriousmedical
problems and even deaths among K2 users.