Nerve cells in the brain are called neurons. These neurons "talk" to each other by passing chemicals back and forth, just like passing notes in class. The neurons' "notes" are called neurotransmitters, and they are manufactured in vesicles in the nerve cell. Neurotransmitters include serotonin, acetylcholine, norepinephrine, dopamine, histamine and about two dozen others.
The nerve cells are separated by a small space called a "synapse." When a message moves down the axon of the pre-synaptic neuron, neurotransmitters are released from the vesicle. These chemicals (or notes) cross the synapse to the post-synaptic neuron, where they bind with receptors specifically designed to receive them, much as a key is designed to fit into a specific lock.
Many nerve cells have receptors that are sensitive to various drugs. These drugs operate on the "lock-and-key" principle, where the drug can be thought of as the "key" that either (1) fits into the "lock," causing the nerve cell (neuron) to discharge its chemicals, or (2) "jams" the lock, preventing the nerve cell from discharging.
Influences of Psychoactive Drugs
Drugs are often made more tempting when portrayed by users as magical or possessing special properties. For example, in the 1960s, LSD was considered by many to be a "mind-expanding drug." Quaaludes were called "peace pills," "love drugs," "super zoom," etc. These attractive descriptors likely helped persuade others to experiment.
Today's drugs of abuse are no different. PCP is called "angel dust," pure methamphetamine is sold as "ice," and MDMA, a designer drug, is called "ecstasy." No matter what type of nickname a psychoactive drug possesses, it basically produces its effect by altering the powerful neurotransmitters in the brain.
When students can describe scientifically how this process occurs with different types of drugs, they are less likely to be impressed by glamorous "street names" given to these substances. They are also much less likely to think that a psychoactive (mood-altering) drug can confer magical abilities or powers on the user.
The influence of psychoactive drugs is almost entirely limited to changes in the synapse. The exception would occur where the drug itself produced changes in other parts of the neuron, such as the cell membranes. For example, hallucinogens are believed to cause synesthesia ("seeing" sounds, "hearing" colors) by mimicking serotonin, acetylcholine and norepinephrine.
The mechanisms of drug action include: