Acupuncture and Hormone Balance
Chapter 6: Dopamine
opamine is a chemical messenger responsible for transmitting signals between nerve cells. It is very important in the transmission of impulses from the nerve cells of the substantia nigra to those of the corpus striatum to facilitate smooth, purposeful muscle activity. Dopamine is the immediate metabolic precursor of norepinephrine (also called noradrenaline) and epinephrine (also called adrenaline); it is the raw material from which the other two chemicals are made. Dopamine can have either an excitatory or inhibitory effect on nerve cells, depending on the characteristics of their receptors.
Functions of Dopamine
1. Nerves using dopamine as their chemical messenger extend their connections into various regions of the brain, controlling different functions by stimulating different kinds of receptors.
2. Dopamine influences the perception of pain and pleasure. Commonly associated with the 'pleasure system' of the brain, dopamine provides feelings of enjoyment that motivates us to do or to continue to do certain activities. Dopamine is greatly involved in the feelings of reward, alertness, and purposeful behavior. Of course, dopamine is released by naturally rewarding experiences such as food, sex, and the use of certain drugs.
3. Dopamine affects the flow of information from other parts of the brain to the frontal lobes, the anterior part of the cerebral cortex. Dopamine disorders in this part of the brain can cause problems in memory, attention, and problem solving. In milder disorders, too much dopamine in the limbic system, a network of brain structures associated with emotion and memory, and not enough in the cerebral cortex may produce an overly suspicious personality prone to bouts of paranoia or may inhibit social interaction.
4. Dopamine can increase heart rate, heart contraction strength and blood pressure. The dopamine-induced release of norepinephrine from nerve terminals contributes to these effects. Although dopamine usually increases the systolic and pulse pressures, it has little or no effect on the diastolic blood pressure.
5. Within a certain dosage range, dopamine increases blood flow to the kidneys to improve kidney function and the excretion of sodium.
6. Dopamine also functions as a neurohormone released by the hypothalamus. Its main function as a hormone is to inhibit the release of prolactin, a chemical that stimulates milk production, from the the pituitary gland...