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Serotonin: 9 Questions and Answers
1. What is serotonin?
Serotonin acts as a neurotransmitter, a type of chemical that helps relay signals from one area of the brain to another. Although serotonin is manufactured in the brain, where it performs its primary functions, some 90% of our serotonin supply is found in the digestive tract and in blood platelets.
2. How is serotonin made?
Serotonin is made via a unique biochemical conversion process. It begins with tryptophan, a building block to proteins. Cells that make serotonin use tryptophan hydroxylase, a chemical reactor which, when combined with tryptophan, forms 5-hydoxytryptamine, otherwise known as serotonin.
3. What role does serotonin play in our health?
As a neurotransmitter, serotonin helps to relay messages from one area of the brain to another. Because of the widespread distribution of its cells, it is believed to influence a variety of psychological and other body functions. Of the approximately 40 million brain cells, most are influenced either directly or indirectly by serotonin. This includes brain cells related to mood, sexual desire and function, appetite, sleep, memory and learning, temperature regulation, and some social behavior.
In terms of our body function, serotonin can also affect the functioning of our cardiovascular system, muscles, and various elements in the endocrine system. Researchers have also found evidence that serotonin may play a role in regulating milk production in the breast, and that a defect within the serotonin network may be one underlying cause of SIDS (sudden infant death syndrome).
4. What is the link between serotonin and depression?
There are many researchers who believe that an imbalance in serotonin levels may influence mood in a way that leads to depression. Possible problems include low brain cell production of serotonin, a lack of receptor sites able to receive the serotonin that is made, inability of serotonin to reach the receptor sites, or a shortage in tryptophan, the chemical from which serotonin is made. If any of these biochemical glitches occur, researchers believe it can lead to depression, as well as obsessive-compulsive disorder, anxiety, panic, and even excess anger.
One theory about how depression develops centers on the regeneration of brain cells -- a process that some believe is mediated by serotonin, and ongoing throughout our lives. According to Princeton neuroscientist Barry Jacobs, PhD, depression may occur when there is a suppression of new brain cells and that stress is the most important precipitator of depression. He believes that common antidepressant medications, such as Celexa, Lexapro, Prozac, and Paxil -- designed to boost serotonin levels -- help kick off the production of new brain cells, which in turn allows the depression to lift.
Although it is widely believed that a serotonin deficiency plays a role in depression, there is no way to measure its levels in the living brain. Therefore, there have not been any studies proving that brain levels of this or any neurotransmitter are in short supply when depression or any mental illness develops. And while blood levels of serotonin are measurable -- and have been shown to be lower in people who suffer from depression -- what doctors still don't know for certain is whether or not the dip in serotonin causes the depression, or the depression causes serotonin levels to drop.
Antidepressant medications that work on serotonin levels -- medications known as SSRIs (selective serotonin reuptake inhibitors) and SNRIs (serotonin and norepinephrine reuptake inhibitors) are believed to reduce symptoms of depression, but exactly how they work is not yet fully understood.
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Important Safety Information
Cymbalta® (duloxetine HCl) is approved for the treatment of depression and generalized anxiety disorder, and for the management of diabetic peripheral neuropathic pain and fibromyalgia.
What should I talk about with my healthcare provider?
Patients on antidepressants and their families or caregivers should watch for new or worsening depression symptoms, unusual changes in behavior, thoughts of suicide, anxiety, agitation, panic attacks, difficulty sleeping, irritability, hostility, aggressiveness, impulsivity, restlessness, or extreme hyperactivity. Call your healthcare provider right away if you have thoughts of suicide or if any of these symptoms are severe or occur suddenly. Be especially observant within the first few months of antidepressant treatment or whenever there is a change in dose.
You should also know that:
- Suicide is a known risk of depression and some other psychiatric disorders.
- Antidepressants may increase suicidal thoughts or behaviors in some children, adolescents, and young adults especially within the first few months of treatment or when changing the dose. No increased risk has been shown for adults over age 24, and risk decreased for those over age 65.
- All patients starting therapy should be monitored appropriately and observed closely for new or worsening depression symptoms, suicidal thoughts or behavior, or unusual changes in behavior.
- Cymbalta® is not approved for use in patients under age 18.
Who should NOT take Cymbalta?
You should not take Cymbalta if:
- You have recently taken a type of antidepressant called a monoamine oxidase inhibitor (MAOI)
- You have uncontrolled narrow-angle glaucoma (an eye disease)
- You are taking Mellaril® (thioridazine)
What other important information should I discuss with my healthcare provider?
Before starting Cymbalta, tell your healthcare provider:
- about all of your medical conditions, including kidney problems, glaucoma, or diabetes
- about your alcohol use
- if you are taking nonprescription or prescription medicines, including those for migraine, to address a possible life threatening condition
- if you are taking NSAID pain relievers, aspirin, or blood thinners. Use with Cymbalta may increase bleeding risk
- if you are pregnant, plan to become pregnant during therapy, or are breastfeeding an infant
While taking Cymbalta, tell your healthcare provider:
- if you have itching, right upper belly pain, dark urine, yellow skin/eyes, or unexplained flu-like symptoms, which may be signs of liver problems. Severe liver problems, sometimes fatal, have been reported
- if you have high fever, confusion, and stiff muscles to address a possible life-threatening condition
- before stopping Cymbalta or changing your dose
- if you experience dizziness or fainting upon standing, especially when first starting Cymbalta or when increasing the dose. Your healthcare provider may periodically check your blood pressure while you are taking Cymbalta
If you have any questions, talk to your healthcare provider before taking Cymbalta.
What are the possible side effects of Cymbalta?
The most common side effect of Cymbalta was nausea. For most people who had it, the nausea was mild to moderate. Other common side effects included dry mouth, sleepiness, constipation, decreased appetite, and, increased sweating. This is not a complete list of side effects.
Depression Glossary
- Antidepressant: Drugs to be used to treat depression...
- Dysphoria: An emotional state marked by anxiety, depression, and restlessness ...
- Dysthymia: Chronic depression that is less severe than major depression ...
- Major Depression: Depression that lasts for at least two weeks and interferes with daily life ...
- Psychotherapy: Treatment by talking about emotional problems ...
- View All Terms
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