Serotonin’s Role in Ejaculation

Serotonin, a chemical in your brain, plays an important role in your sex life, including ejaculation.

A chemical messenger, or neurotransmitter, serotonin is also important for your mental health. That’s why certain antidepressants that affect serotonin can have sexual side effects. These include problems with:

• Desire
• Arousal
• Ejaculation
• Orgasm

This article will go over the role that serotonin and other neurotransmitters play in ejaculation and why some medications for depression may affect your sexual satisfaction. 

The Biology of Ejaculation

Ejaculation starts with arousal. While you may start to get aroused by being touched (direct stimulation) you may also become aroused just by thinking “sexy thoughts” (indirect arousal). 

Chemicals in your brain called neurotransmitters help turn thoughts into sexual arousal:

• Serotonin
• Norepinephrine
• Dopamine

Much of our understanding of the role of neurotransmitters and brain structures in arousal and orgasm comes from animal research. However, there have been human studies as well.

Through research, scientists have learned that several areas of the brain are associated with male sexual function.

The medial preoptic area (MPOA) of the hypothalamus is central to the sexual response. This is where sexual stimuli from various parts of the body come together for processing.

The brain then sends signals down the spinal cord that cause the body to become aroused and then orgasm. Parts of the amygdala and the parietal cortex are also important in the control of ejaculation.

Studies have shown it’s possible to make rats orgasm just by activating certain neurotransmitter receptors in their brains.

Role of Neurotransmitters

In humans, serotonin is the neurotransmitter most clearly associated with ejaculation. SSRIs work by preventing cells from reabsorbing (reuptaking) serotonin. This means that the signals caused by serotonin are extended, lasting for a longer time.

Studies in rats have also shown that where serotonin is located in the brain changes its effects. For example, if serotonin is injected into some parts of the rat brain, it causes delayed ejaculation. When it’s put in other areas of the brain, serotonin makes ejaculation happen.

Dopamine also plays a role in ejaculation, although its role has not been explored as much as serotonin’s role.

Rat studies have also shown that dopamine stimulation can cause ejaculation.

Another example of the link between dopamine and ejaculation is seen in people with schizophrenia who are treated with antipsychotic drugs that block a particular type of dopamine receptor (D2-like receptors). Often, these patients find it difficult—if not impossible—to ejaculate. The same drugs have been tested as a treatment for people with premature ejaculation.

Similar to SSRIs, antipsychotics seem to extend the time between arousal and ejaculation. There is also some data showing that mutations in dopamine transporters may make some people more likely to experience premature ejaculation.

Phases of Ejaculation

Ejaculation is the forceful propulsion of semen from the body. It takes place in two phases.

• The first phase is referred to as emission. That is when the various components of the semen, including sperm, are secreted from various glands and organs.
• The second phase is expulsion. That is when intense contractions of the muscles in the genital region cause semen to be pushed out of the penis.

Some people who have had certain types of prostate cancer surgery may experience “dry” ejaculation because their bodies no longer make the fluid components of semen.

Approximately one-third of seminal fluid comes from the prostate. Other glands that contribute to seminal fluid production can also be affected by cancer surgeries.

Some people who are multi-orgasmic may have multiple orgasms with only one ejaculation. Other people are not able to ejaculate at all (anejaculation).

There typically is a refractory period after ejaculation before a person again is able to achieve erection and ejaculation.

Erection vs. Ejaculation

An erection is not required for ejaculation to occur. Ejaculation without an erection is not common, but it is possible.

The most frequent example happens to adolescents while they sleep (nocturnal emissions or “wet dreams”). Nocturnal emissions can occur with or without an erection.

Ejaculation without erection can also be stimulated using the vibration of the penis in people with certain types of spinal cord injury. This technique can also be used to collect sperm for assisted reproduction procedures.

Though the physiological pathways that lead to erection and ejaculation are related, they are not the same. This is why the PDE-5 inhibitors used to treat erectile dysfunction do not have a major effect on a person’s ability to ejaculate.

These medications affect the flow of blood in and out of the penis. They do not affect the release of the semen components or the muscle contractions involved.

Summary

Serotonin and other neurotransmitters are involved in sexual arousal and play a role in ejaculation for people with a penis. That’s one reason why many people who take certain antidepressants experience sexual side effects.

While a lot of the research on neurotransmitters and ejaculation has been in animals, there have been some human studies to suggest that brain chemicals are a key player in human arousal.

If you’re taking a medication that you think could be having a negative effect on your sexual satisfaction, talk to your provider. You might be able to change your dose or switch to another medication that’s less likely to interfere with your sex life.