Dopamine is a chemical messenger which is produced in several areas of the human brain. The five known types of dopamine receptors in humans are D1 through to D5. These receptors are located in the brain, the central nervous system, the blood vessels, and the kidneys. Part of the protein family, dopamine receptors sit on the surface of a cell. They can detect dopamine molecules outside of the cell and activate a response.
Brain processes such as pleasure, cognition, motivation, learning, movement, and memory, among others, may be affected by the number of dopamine receptors as well as their ability to signal a response. Any change in dopamine levels can increase or reduce the number of receptors. Variations in receptor numbers hold the risk of a change in the person’s mental and physical well-being, ranging from mild to severe.
How Dopamine Agonists Work
In the absence of dopamine, a dopamine agonist can activate dopamine receptors. It does this through stimulating the signaling pathways of dopamine receptors and the proteins that are responsible for carrying dopamine. This process may eventually leads to changes in gene makeup.
Dopamine agonists work by stimulating dopamine receptors in the opposite way to dopamine antagonists, which block rather than stimulate dopamine receptors. In promoting dopamine receptors, dopamine agonists increase the capacity of the dopamine receptors to collect dopamine. They effectively turn up dopamine activity. This return to the normal workings of the receptors can be used to remedy various sicknesses, such as Parkinson’s disease, which is commonly connected with an underactive dopamine system.
Use of Dopamine Agonists
Drugs that act as dopamine agonists can be used to treat conditions linked with low dopamine levels, such as select pituitary tumors (prolactinoma), restless leg syndrome (RLS), and Parkinson’s disease – in both early or advances stages.
Trials are underway to assess the effectiveness in using dopamine agonists to ease the symptoms which cocaine dependents experience during an initial withdrawal period from cocaine. This controversial treatment may be useful in helping drug abusers to overcome addiction.
Research to test the effectiveness of dopamine agonists in treating sexual dysfunction caused by selective serotonin reuptake inhibitors (SSRI) is also in progress. Additionally, dopamine agonists have been found to be useful in reducing the frequency of ovarian hyperstimulation syndrome (OHSS) in women undergoing in vitro fertilization (IVF) treatment.
Side Effects of Dopamine Agonists
Side effects linked with dopamine agonists may include:
* Increased intensity of orgasms
* Orthostatic hypotension
* Weight loss
* Abnormal weakness or tiredness
* Twitching or other abnormal body movements
* Fainting, dizziness, lightheadedness, or drowsiness
* Impulse control disorders (such as to gambling or hypersexuality)
* Compulsive behavior
Dopamine Agonist Drugs
Common dopamine agonists include:
* Apokyn (apomorphine)
* Dostinex (cabergoline)
* Mirapex and Sifrol (pramipexole)
* Neupro (rotigotine)
* Norprolac (quinagolide)
* Parlodel (bromocriptine)
* Permax (pergolide)
* Requip (ropinirole)
Effect of Drug Abuse on Dopamine Levels
The abuse of drugs such as amphetamine and cocaine can have an effect on normal dopamine function. Repeated stimulation of dopamine receptors decreases the number of receptors, while those that remain become less sensitive to dopamine. This desensitization is commonly known as tolerance. Among its many uses, dopamine agonists can treat conditions associated with low dopamine levels through the activation of the signaling pathways of dopamine receptors.