Serotonin as a neurotransmitter: Depression? What is serotonin's role in the body? How does serotonin affect prosocial behavior? What is an SSRI and how does it work?

Serotonin is one of the, if not most, discussed neurotransmitters in the world of clinical psychology and medical settings. Neurotransmitters like serotonin act as chemical messengers which transmit signals between consecutive neurons or neurons to muscles. They play a very important role in brain-body signaling and body-system regulation. Every neurotransmitter is released from a neuron. These neurotransmitters then travel across the synapse (space between two neurons) and bind onto receptors on the next neuron, which allows it to act as a transferrable message across the body.

Serotonin, in itself, serves many functions in our body. It is responsible for regulating our mood, appetite, and sleep. It’s typically found in our gut (gastrointestinal tract) and the central nervous system (the brain, spine and peripheral nerves). In our gut, it is also responsible for bowel movement and bowel stability.

Prosocial behavior talks about the ability of a person to do acts which will benefit others (in other words, selfless acts). Serotonin is often a large influencer of whether a person is prosocial or not. Research shows that varying levels of serotonin can imbalance the prosocial attitude of people. Higher serotonin levels between the synapses indicate increased cooperation, empathy for others, and even lower levels of aggression. This, is why some people with depression (who typically have low levels of serotonin) are less prosocial: they become irritable, numb and frustrated with day-to-day functioning.

SSRIs (Selective Serotonin Reuptake Inhibitors) are a type of medication used to treat people with anxiety, depression or other mood disorders. Its long name explains the way it functions in our body. Our neurons tend to reabsorb excess serotonin to prevent imbalances in our body system; however, people with depression, their bodies tend to absorb even the necessary serotonin from between the synapses, which prevents their mood from being regulated and leads to symptoms like extreme lows or highs in appetite, insomnia, etc. SSRIs work by inhibiting (stopping) the reuptake of serotonin by our neurons and allows the serotonin to pass through the synapses efficiently.

Some examples of SSRIs include fluoxetine, sertraline or escitalopram. By blocking reuptake, they increase the concentration of serotonin in the synaptic cleft (another word for the space between neurons.) With higher concentration of the neurotransmitter in the cleft, there is enhanced signaling between consecutive neurons and the body begins to function with higher mood regulation and other functions of serotonin.

Neurotransmitters act as a very important part of our body’s nervous system, and imbalances in the concentration or even timing of the release of these neurotransmitters can affect us negatively. In the modern world, different medications like SSRIs can be used to treat conditions wherein neurotransmitters are out of balance in our body: helping us to get our serotonin levels back to normal.