Dopamine levels refer to the amount of dopamine in the body. Dopamine is a neurotransmitter and, in the brain, activates dopamine receptors and is involved in 'rewarding feelings' and addiction. Dopamine is also a neurohormone released by the hypothalamus and, as a hormone, it inhibits the release of prolactin. Dopamine is sometimes given intravenously to increase heart rate and blood pressure; however, dopamine given this way does not affect the brain because it cannot cross the blood-brain barrier. To increase the levels of dopamine in the brain, a precursor of dopamine, L-DOPA, is given and this form can cross the blood-brain barrier.
Functions
According to "Basic Neurochemistry: Molecular, Cellular and Medical Aspects, 7th Edition", the functions of dopamine in the brain include voluntary movement, motivation, punishment and reward, attention, working memory, mood, sleep, cognition and learning. Dopamine is released during rewarding experiences such as sex, drugs and eating and also other neutral experiences which become associated with rewarding ones. Due to this association of dopamine with rewarding experiences, this neurotransmitter plays a role in addiction.
Dopamine also has important non-neuronal functions. According to "Cell Biology, 2nd Edition," dopamine plays important roles in the function of the immune system and alters the activity of neutrophils, eosinophils, B cells and natural killer cells. Dopamine also exerts an effect on immune cells in the spleen, bone marrow and circulation. When administered intravenously, effects of dopamine include dilation of blood vessels, increased blood flow to the kidneys, increased urine output, increased cardiac output, and increased blood pressure. Thus dopamine is sometimes given to patients with shock or heart failure.
Low Levels
According to Marnia Robinson, co-author of "Peace Between the Sheets," low levels of dopamine are associated with an inability to love and inability to feel pleasure, a lack of remorse from wrong personal behavior, low libido and erectile dysfunction, social anxiety disorder and low ambition. Persons with low dopamine are likely to feel depressed.
High Levels
Marnia Robinson states that high levels of dopamine are associated with psychosis, aggression, anxiety, addictions and compulsions, sexual fetishes, gambling and other compulsive activities, cravings, and risk-taking. S. Lang from Cornell University argues that people with high levels of dopamine tend to be more sensitive to incentives and rewards. This makes them more eager to pursue their goals and ambitions.
References
- "Basic Neurochemistry: Molecular, Cellular and Medical Aspects, 7th Edition"; George Siegel M.D. et al.; 2005
- "Psychologist finds dopamine linked to a personality trait and happiness"; Susan Lang
- "Pulling Away (After Sex)"; Marnia Robinson; 2004
- "Cell Biology, 2nd Edition"; Thomas D. Pollard; 2007
