Dopamine as a Neurotransmitter

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Table of Contents

Introduction
Dopamine
Effects of the transmitter
Effects of excess and low dopamine
Conclusion
Bibliography

Introduction

Neurotransmitters are chemical substances that help in the communication of nerve signals between neurons and other cells. Dopamine is one such important catecholamine neurotransmitter found in the brain. In addition to its other functions, one of its main functions is to control the movement of the body. However, any excess or low levels of dopamine can lead to various diseases in the body like schizophrenia and Parkinson’s disease. This essay describes the chemistry of dopamine, its various effects and the effects of excess or low levels of dopamine.

Dopamine

Dopamine is one of the neurotransmitters present in the extrapyramidal system of the brain (Genetics Home Reference 2008). It is a catecholamine and helps in the formation of other catecholamines like norepinephrine and epinephrine (Powers 2008).

Dopamine is produced from L-dihydroxyphenylalanine (L-dopa) through the action of the enzyme dopa decarboxylase (Powers 2008). The action of dopamine starts when it binds to dopamine receptors present in the body. The main areas of synthesis of dopamine in the brain includes: arcuate nucleus, hypothalamus and the caudad (Davidson.edu 2003). The levels of dopamine is regulated by an enzyme called monoamine oxidase (MAO) (Davidson.edu 2003).

Effects of the transmitter

Dopamine helps to control body movements, regulates mood and emotion, and controls the secretion of few hormones (Powers 2008). In addition to these functions, dopamine also plays an important role in the reward system of the brain, and thereby, plays a role in drug addiction (Powers 2008).

Effects of excess and low dopamine

Excess levels of dopamine in the brain may probably lead to a psychiatric disorder called schizophrenia. Schizophrenia is characterized by symptoms like delusions and altered behavior. The exact mechanism of how it causes this disease is not known (Psychiatric-disorders.com 2008).

Drugs like cocaine and amphetamine increase the levels of dopamine and causes psychotic symptoms like that in schizophrenia. Therefore, it is said that in a similar way, increased levels of dopamine in the brain also probably causes schizophrenia (Psychiatric-disorders.com 2008).

When the levels of dopamine in the brain become low, it leads to a condition known as Parkinson’s disease (Powers 2008). The usual onset of Parkinson’s disease is at around 60 years, but it may start at an earlier age, and is more common in men than in women.

This disease is characterized by: trembling of hands, arms, legs, jaw and face, stiffness of the arms, legs and trunk, slowness of movement, poor balance and coordination.

In the late stages of Parkinson’s disease, the patient may have difficulty in walking, talking, or doing routine activities. The condition may be associated with depression, sleep problems or difficulty in chewing, swallowing or speaking.

Among the various treatment used for Parkinson’s disease, one of the commonly used treatment is L-dopa. L-dopa gets converted to dopamine in the body and thus relieves the symptoms of Parkinson’s disease (Medline Plus 2008).

Conclusion

Dopamine is a catecholamine neurotransmitter found in the extrapyramidal system of the brain. It is synthesized from the compound L-dopa. The main areas of synthesis of dopamine in the brain includes: arcuate nucleus, hypothalamus and the caudad. The enzyme monoamine oxidase (MAO) helps in the regulation of dopamine levels in the body.

The functions of dopamine include: control of body movements, regulation of mood and emotion and control of the secretion of few hormones. It is also an important component of the reward system in the brain and plays a role in drug addiction.

Excess levels of dopamine in the brain leads to schizophrenia, which is psychiatric disorder. Low levels of dopamine causes Parkinson’s disease, which is characterized by tremors, stiffness, slow movement, and difficulty in swallowing chewing etc.

Bibliography

Genetics Home Reference [Internet]. [2008]. Web.

Medline Plus [Internet]. [2008]. Web.

Powers, JL. 2008. Dopamine. Chemistry: Foundations and Applications. FindArticles.com. [Internet]. Web.

Psychiatric-disorders.com. Causes of Schizophrenia: Genetics, Environment, and Dopamine. [Internet]. [2008]. Web.

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