Serotonin: The explanation on how antidepressants work
Serotonin is one of many neurotransmitters found in the blood, mucous membranes lining the digestive tract and stomach, and brain. Serotonin is a chemical that naturally occurs in the human brain, intestines, blood platelets and mast cells. Serotonin is a chemical made from tryptophan, an amino acid found in food (most famously as the substance in turkey that makes people feel tired after the meal). Imbalances in the brain's neurotransmitters cause depression. Higher levels of serotonin are shown to counter depressive symptoms.
Serotonin is a specific neurotransmitter, a chemical that acts as the messenger between two nerve cells in the brain. The nerve cells in the brain are not physically connected to one another - they are separated from one another by synapses (tiny gaps ). In order for a signal (serotonin) to cross this gap, the first nerve cell shoots the serotonin out and into the gap where it travels to the receptor of the receiving nerve cell. The serotonin, then stimulates the receptors and binds to specific receptor proteins embedded within the cell membrane on the far side of the gap. This binding promotes the generation of a new signal in the receiving nerve cell, thus successfully transferring the signal across the gap. The serotonin is then abosrbed by the receiving cell and the message has been passed.
Typically serotonin is concentrated in two specific areas of the brain -- the midbrain and the hypothalamus. These areas are responsible for regulating mood, hunger, sleep and aggression. Changes in the concentration of serotonin in these areas are linked to a variety of mood disorders, particularly depression.
THC, the active ingredient in marijuana, increases serotonin when smoked in low doses, similar to SSRI antidepressants, such as Prozac, according to researchers from McGill University and Le Centre de Recherche Fernand Seguin of Hôpital in Quebec and l'Université de Montréal in Montreal.
But at higher doses, the effect reverses itself and can actually worsen depression. So - smoking a joint might act as an anti-depressant, but smoking five joints could be harmful.
The anti-depressant and intoxicating effects of cannabis are due to its chemical similarity to natural substances in the brain known as ‘endo-cannabinoids,’ which are released under conditions of high stress or pain. They interact with the brain through structures called cannabinoid CB1 receptors that have a direct effect on the cells producing serotonin.
Serotonin levels are thought to be reduced to below optimal levels when it is returned (or taken up) too quickly or in too great a quantity by neurons after the chemical has transmitted an impulse across a synapse.
Serotonin levels are thought to be reduced to below optimal levels when it is returned (or taken up) too quickly or in too great a quantity by neurons after the chemical has transmitted an impulse across a synapse. With too little serotonin in the gaps between nerve cells, the target receptors on the receiving nerve cells don't fire enough to keep the mood-elevating pathway active, and depression results.
All SSRI medications function by prolonging (or inhibiting) the process by which serotonin is taken up by neurons (the process referred to as "reuptake"). All SSRIs are designed to prolong the reuptake process only for serotonin. To differentiate between serotonin and a host of other chemicals in the brain, they must be highly selective.
"selective serotonin reuptake inhibitors" -- they prevent (inhibit) serotonin (and only serotonin) from experiencing too much or too long of a reuptake process. This makes more serotonin available in the brain. According to Sheldon H. Preskorn, M.D., professor and chair of the department of medicine and behavioral sciences at University of Kansas School of Medicine, Wichita, and author of Applied Clinical Psychopharmacology, SSRIs are effective for a significant number of individuals who use them as directed for this purpose.
Depression is quite often treated by administering extra serotonin in the form of various dosages and types of antidepressants. Antidepressant drugs (Selective Serotonin Reuptake Inhibitors (SSRI's) like Prozac (c)) block the reabsorption of serotonin and allow it to stay in the gap. In so doing, it allows the serotonin to just keep smashing into the receptors across the gap, triggering them to fire at the receiving nerve cells again and again. Each serotonin molecule has a chance to transmit the signal across the gap by hitting a target receptor. If it fails to bind with the new recptor it is either destroyed or reabsorbed by the nerve cell that released it. Many times a patient will have to play the dreaded drug shuffle while finding a suitable antidepressant. This process takes a very long, long time.
Beneficial Side Effects of ingesting THC:
In the ten years or so, scientists have discovered two receptors [CB1 and CB2] in the brain which are affected by the cannibinoids found in THC in marijuana. Ian Meng, a researcher at the University of California, San Francisco, is said to liken the relationship between these brain receptors and cannibinoids, to a lock and key. The receptors are on the nerve cell membrane and they're the lock and the cannibinoid, the key, opens this lock and unleash all of the nerve cells' actions. Meng discovered these actions include a process similar to the release of natural endorphins which results in pain reduction. THC can activate a very specific population of neurons to reduce the pain signal - just like the natural endorphins do.
Investigations into the study of marijuana and serotonin showed that mental states such as depression are determined by the individual having too little serotonin. While the relationship is a very complex one, there is strong evidence that serotonin is involved in regulating human violence, aggressive behaviors, suicide, appetite and hunger. These actions have all been associated with reduced levels of serotonin in the brain.
Sources:
The first SSRI to be approved by the U.S. Food and Drug Administration was Prozac in 1987; the most recent was Celexa in 1998. The five SSRIs presently approved for use in the United States are:
fluvoxamine maleate (Luvox) manufactured by Solvay
paroxetine (Paxil) manufactured by Smith Kline Beecham
sertraline (Zoloft) manufactured by Pfizer
citalopram (Celexa) manufactured by Forest Laboratories
fluvoxetine (Prozac) manufactured by Eli LillyHeavy Marijuana Use Doesn't Damage Brain - Analysis of Studies Finds Little Effect From Long-Term Use
Long-term and even daily marijuana use doesn't appear to cause permanent brain damage, it was found only a "very small" impairment in memory and learning among long-term marijuana users. 700 regular marijuana users were compared with 484 non-users on various aspects of brain function -- including reaction time, language and motor skills, reasoning ability, memory, and the ability to learn new information. The marijuana users - had smoked marijuana several times a week or month or daily.
This confirms what was known over 100 years ago, as well as what was learned by various government findings doing similar research -- marijuana is not toxic, but it is a highly effective medicine. In fact, marijuana was available as a medicinal treatment in the U.S. until the 1930s.
Lester Grinspoon, MD, a retired Harvard Medical School psychiatrist who studied medicinal marijuana use since the 1960s and wrote two books on the topic, is reported to have stated "it's nothing that those of us who have been studying this haven't known for a very long time. " "Marijuana is a remarkably safe and non-toxic drug that can effectively treat about 30 different conditions, I predict it will become the aspirin of the 21st century, as more people recognize this."
SOURCES:
Sid Kirchheimer
Reviewed By Michael Smith, MD
on Tuesday, July 01, 2003
WebMD Medical News
www.medicinenet.com
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In order for one neuron to communicate with another neuron it must send a signal. These signals are chemicals called neurotransmitters. Neurotransmitters are the "messenger" chemicals in the brain.
When it is time to communicate with another neuron, the sending neuron releases the "messengers" into the gap between the neurons. This gap is called the synapse. The "messenger" crosses the synapse and travels to the receptors on the receiving neuron on the other side of the synapse.
Receptors are "binding sites" for the "messengers" in the brain. They instruct neurons to regulate various brain and body functions. Their actions are triggered by neurotransmitters if there is a precise fit, or a "bind," between the transmitter and the receptor. If the transmitter molecules don’t fit exactly into a receptor, then nothing happens. If it fails to bind with the new recptor it is either destroyed or reabsorbed by the nerve cell that released it.
The neurotransmitter we often look at in depression is serotonin. Serotonin is believed to regulate mood, sleep, and learning.
With too little serotonin in the gaps between nerve cells, the target receptors on the receiving nerve cells don't fire enough to keep the mood-elevating pathway active, and depression results.
Depression is quite often treated by administering extra serotonin in the form of various dosages and types of Antidepressant drugs called - Selective Serotonin Reuptake Inhibitors (SSRI's).
The SSRI's block the reabsorption of serotonin and allow it to stay in the synapse longer. In so doing, it allows the serotonin to just keep binding onto more receptors across the synapse. Thus, completing the transmission of the original message.
Research into depression found that the THC in Marijuana (in low doses) also increases the time the serotonin stays in the gaps between nerve cells. By doing so, it increases the number of hits to target receptors.
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