This is the fourth installment of a five part series on the neurobiology of addiction by Jennifer Fernández, PhD.
Drugs act on neurotransmitters to increase, decrease, or alter their release or reuptake.
In the previous installment of this series, we learned that dopamine is responsible for feelings of pleasure and euphoria, but it has other functions as well. And dopamine isn’t the only chemical messenger in the brain.
Dopamine is just one of dozens of neurotransmitters. It is the most well known chemical messenger and is responsible for feelings of pleasure, coordination of movement, and logical thinking. It is responsible for “the rush” one feels when they use a recreational drug and it also influences the addictive potential of a drug. It is released when we do things that are important for survival, like sleeping, eating, and having sex. Dopamine sends the message “That feels good! Do it again!”
Norepinephine is one of the brain’s natural stimulants. It is responsible for increased alertness and focus and is involved with learning and memory processes. Norepinephrine is also involved in the fight or flight response. It signals the release of adrenaline in your body to prepare you for survival in the face of imminent danger. It sends the message “Fight!” or “Run!”
GABA (gamma-aminobutyric acid) is the brain’s Valium. It relaxes the brain by suppressing overexcitement or hyperactivity, while allowing us to remain alert and focused. Low levels of GABA are associated with anxiety and seizure.
Glutamate stimulates various activities throughout the brain. We don’t know much about how it is involved in mood regulation.
Serotonin plays several complex roles in the brain. It is involved in regulating mood, sleep, appetite, and sex drive. Low levels of serotonin are associated with aggression, irritability, and depression. Serotonin is also responsible for hallucinations and regulating other neurotransmitters.
Endorphins are the brain’s natural opiates. They influence the perception and control of physical and emotional pain. In addition to pain relief, they are responsible for feelings of well-being, happiness, and euphoria.
Drugs act on these messenger chemicals to increase, decrease, or alter their release or reuptake. Our brain is wired to recognize these chemicals and accept their messages. The difference is that drugs relay the message better, faster, and in a much more intense way. Research shows us that life experiences affect the development of the brain, including how neurotransmitters work. For example, someone who has experienced trauma may find it difficult to feel pleasure or regulate their mood due to low levels of dopamine and serotonin. This may cause them to turn to externally supplied chemicals to balance the levels of neurotransmitters in their brain.
The next, and final, installment of this series will explain why some people turn to recreational drugs in an attempt to balance the chemical messengers of the brain.
Photo credit: Life Mental Health