Dopamine Transporter

Human dopamine acts as a hormone and is also a neurotransmitter which allows people to feel pleasure, satisfaction, and motivation.  A high dopamine release may be achieved through getting adequate sleep, exercising, meditating, listening to music, and eating a balanced diet. 

The human dopamine transporter (DAT) is a sodium-dependent dopamine transporter and protein that crosses the plasma membrane to manage dopamine uptake. DATs are one of three monoamine transporters designed to cross the plasma membrane. Dopamine is derived from the amino acid tyrosine. 

Abnormalities in the dopamine transporter gene or its function are linked to several conditions, including bipolar disorder, attention deficit hyperactivity disorder (ADHD), and Parkinson's disease. While dopamine is necessary to our wellness, extracellular dopamine may contribute to the vulnerability in some individuals to drug use. The DAT function is designed to clear dopamine from the extracellular space. 

If you believe you may be living with a dopamine-related mental health concern, online therapy may be helpful.

Components of the mesolimbic dopamine system

Dopamine is the key component of the mesolimbic dopamine system. The mesolimbic system is composed of a network of dopamine neurons, or neurotransmitters, in the human brain. This system can receive and process stimuli and is typically associated with physical movement and human emotion. It includes the presynaptic neuron, where dopamine is released, and the postsynaptic neuron, where dopamine receptors are located.

The dopamine system functions in a process that synthesizes dopamine, releases it in response to outside stimuli, and then returns it to the brain cell. Through this process, your brain may respond to stimuli by giving you pleasure or the feeling of reward. When the dopaminergic system is working properly, you can often feel pleasure, reward, or motivation without disrupting your emotional or physical homeostasis.

When something goes wrong with the dopamine system, problems can occur that impair our functioning, not just within our brains but in our everyday lives as well.

What dopamine is and its function

Dopamine is a neurotransmitter as well as a catecholamine, meaning that it can act as both a neurotransmitter and a hormone. Neurotransmitters are chemicals secreted by neurons that carry messages from one brain synapse to another. A synapse is a tiny space between neurons through which messages are transmitted. Hormones are chemicals that act as messengers involved in various biological processes.

Dopamine is a part of the brain’s internal reward system. When you do something that’s satisfying in some way, dopamine is typically what sends the signal that allows you to feel pleasure. Dopamine can pump up your motivation because you may want to feel that pleasurable reward. It can also translate the thought of doing something into the action itself. 

Dopamine receptors are the areas of the brain that accept the message delivered by the dopamine system. Certain neurons can be sensitive to dopamine, and these are generally the ones that receive the dopamine transmissions. 

How dopamine is made

Dopamine is made at the end of the nerve using tyrosine that comes across the blood-brain barrier. The dopamine that is synthesized functions as a neurotransmitter immediately or is converted to norepinephrine or epinephrine.

Dopamine transporters

The human dopamine transporter (DAT) is a protein located in the plasma membrane of the presynaptic neuron. Monoamine transporters, including DAT, are responsible for the reuptake of monoamines such as dopamine, norepinephrine, and serotonin from the synaptic cleft. DAT typically ends the process of dopamine transmission by mediating dopamine reuptake, which involves the reabsorption of extracellular dopamine back into the presynaptic neuron (nerve cell). This reuptake of dopamine can allow you to maintain a relatively steady emotional and physical level. 

DAT is a protein encoded by the dopamine transporter gene (SLC6A3) and is responsible for DAT-mediated dopamine reuptake, which helps maintain extracellular dopamine levels. Striatal dopamine reuptake is a process that occurs primarily in the striatum, a region of the brain responsible for motor control, reward, and reinforcement. The efficiency of striatal dopamine reuptake is crucial for maintaining normal brain function.

Protein kinases are enzymes that modify proteins through the addition of phosphate groups. These enzymes can modulate DAT function by altering its protein structure. Sodium ions are also involved in the function of DAT, as they help to drive the reuptake of dopamine. The protein structure of DAT is crucial for its proper functioning, and any changes to this structure can affect its ability to transport dopamine.

When dopamine is released

Dopamine release occurs when certain outside stimuli are present. For instance, something may happen that catches your attention, and the cells may respond by releasing dopamine, which can produce a feeling of pleasure or satisfaction. Dopamine is usually released only when tyrosine is present between and in the brain cells. This can happen at a rate determined by the tyrosine level and the effect of the receptors on the process.

How dopamine is released

It is the action of the tyrosine on the receptor cells that usually releases dopamine. This can be a complex process that relies on all parts of the dopamine system, from the cells that release the dopamine to the receptor cells and back as the dopamine is taken up again. 

Dopamine transporter dysfunction

When something goes wrong with the dopamine transporter, there may be a high or low level of dopamine between the synapses of the brain. These changes in dopamine can cause several physical and psychological problems.

A trained healthcare provider can provide a clinical diagnosis for a dopamine-related disorder based on a person’s medical history, symptoms, and complete evaluation. Various tests may be used to analyze dopamine in the brain. For example, dopamine transporter imaging is a diagnostic tool that uses radioligands to visualize and quantify DAT density in the brain. This imaging tool is helpful for investigating the role of DAT in various neurological disorders. Understanding DAT function may help in developing targeted treatments for these conditions.

Dopamine beta-hydroxylase (DBH) deficiency

DBH is an enzyme used in the dopamine system. DBH deficiency is a rare genetic disorder that affects the conversion of dopamine to norepinephrine, a vital neurotransmitter involved in various physiological functions such as mood control, attention, and stress response. Dopamine beta-hydroxylase deficiency can happen in infancy. It can cause low blood pressure, vomiting, and dehydration. It may also lower body temperature and blood sugar. 

Parkinson's disease

Parkinson’s disease can happen when the brain begins to atrophy, which usually happens later in life. The nerves may be affected by Parkinson’s to such a degree that you may develop a tremor, muscle rigidity, slow movement, trouble with balance, and begin to walk in a shuffling way.

What does the dopamine transporter have to do with these symptoms? A lack of available dopamine in the brain’s nerve cells can cause hesitations in your response to stimuli. Your brain may know what you want to do but have trouble making it happen smoothly.

Standard treatment for Parkinson’s has generally been the drug L-dopa or levodopa. This drug is the chemical dopa that is usually used in your brain to synthesize dopamine. Aside from that, Dopamine agonist drugs are commonly used in the treatment of Parkinson's disease.

Memory problems

When nerve cells are lost through some form of dementia, the function of the dopamine transporters can be impaired. They may be unable to pass along the messages from one neuron to the next, so memories may not be sent to the areas of the brain.

Bipolar disorder

The connection between bipolar disorder and dopamine has been identified at the level of the genes. Although it’s still unclear how this works, evidence shows that there may be a strong connection between having a specific genetic variant for the dopamine transporter and having bipolar disorder. The same type of connection can be found in people with schizophrenia and depression.

Depression

The availability and function of the dopamine transporters may have a profound influence on whether you have depression or not. Antidepressants often seem to relieve depression by changing these factors.

The dopamine may be taken up and bound by chemical reactions more readily in people with depression than those who aren’t depressed. People with depression often have a higher availability of dopamine transporters. After treatment, there may be fewer available transporters, so the dopamine isn’t so thoroughly removed from the equation.

ADHD

It can be hard to say what causes ADHD, but research shows there may be a strong connection between ADHD and increased dopamine transporters.

When you have an overabundance of dopamine transporters, you may have less dopamine available in your brain. That can be because the transporters end the transmission of the message of pleasure, motivation, or reward. They may not allow the message to move on to the next cell or may cause it to move at a slower rate. This relationship between attention deficit hyperactivity disorder (ADHD) and dopamine uptake has significant implications for understanding and treating the condition.

Alcoholism

Alcoholism can result in a state where you have low levels of dopamine. This dopamine deficiency may be related to depression or other mental problems. In one study, scientists followed the behavior of rats dependent on alcohol. Both dopamine transporters and dopamine receptors were decreased in their brains.

The rats showed behavior appearing to be alcohol cravings. The brains of deceased people with alcoholism were also studied, revealing that dopamine transporters and receptors were frequently altered by alcohol dependence.

Cocaine and amphetamine use

Cocaine can inhibit dopamine transporters. When you take it into your body, the dopamine system may give you a sensation of pleasure as the level of dopamine between the cells rises sharply.

Cocaine can bind to the dopamine transporter so that it can’t end the message properly. While the dopamine chemical process isn’t the same for amphetamines, it can be similar in that it involves dopamine transporters that are locked up with the drug.

Online therapy may help with issues related to dopamine transporters

As explained earlier in the article, several mental health issues may arise when dopamine transporters aren’t functioning properly. If you’re experiencing depression, ADHD, bipolar disorder, or other mental health challenges, therapy may be a valuable tool to help you manage and cope with any symptoms. If visiting a traditional therapist’s office isn’t convenient for you, online therapy can be an effective alternative. It often allows you to book sessions that fit your schedule and speak to licensed professionals from anywhere where you have an internet connection.

Cognitive-behavioral therapy, or CBT, is often used to treat depression and other mental health disorders. According to this study, online CBT can be effective and lead to lasting results.

Takeaway

The job of dopamine transporters is to end the dopamine transmission process and reabsorb dopamine after it has been released. If dopamine receptors aren’t working as they should be, it’s possible for a variety of mental and physical health issues to develop. These may include alcoholism, bipolar disorder, DBH deficiency, Parkinson’s disease, ADHD, depression, memory problems, and others. Please know that if you believe you may be experiencing a dopamine-related mental health problem, online therapy may be a helpful option for you.