Is there really a connection?
As the field of scientific research probes further into the workings of osteoporosis, there emerge more unthought-of factors that play a critical role in the development of the condition. Which chemicals automatically come to your mind when you think of bone conditions like osteopenia or osteoporosis? Vitamin D, Calcium, Magnesium and Phosphorus would be the common guesses. It is unlikely you or anyone would have chanced a guess on serotonin, the well-known and often talked about brain chemical. And yet there seems to exist an almost direct role of this hormone in maintaining our bone health.
What is serotonin?
To those who are unaware of serotonin, here’s a quick look into what this chemical is and does: Essentially it is a protein hormone that is available chiefly in two places in our body – our gut and in our brain though there are other sites where you can detect serotonin presence such as in blood platelets, certain tissues, the pineal body and in the central nervous system.
In the brain, serotonin acts as a neurotransmitter that is involved in the transmission of nerve impulses. A nerve cell/neuron sends a nerve impulse/message to the next nerve cell by releasing serotonin into the nerve gap between two nerve cells, called synapse. After the message is relayed to the next neuron, the serotonin is withdrawn or re-uptaken by the releasing nerve cell. Serotonin also helps regulate moods and allows us to perceive pain, hunger, thirst and sleep. (1)
In the gut, serotonin is linked with functions of gastric fluid release, messaging about satiety etc. (2) Serotonin regulates some physiological functions in the body as well such as stimulation of smooth muscles and vasoconstriction. It also helps regulate body temperature.
What recent research tells us
New research conducted at the Columbia University has it that the serotonin made in our gut is responsible in a crucial way to our rate of bone formation. The study found that production and proliferation of bone-making cells called osteoblast is inhibited by release of gut serotonin. (3) This finding has left the scientists with mixed feelings.
Though the scientists are happy to see the connection, they realize that given the current level of knowledge it is difficult to inhibit or block the release of gut serotonin without having other repercussions for the person in question such as onset of depression, migraines etc.
So how exactly does the serotonin effect bone formation in our body?
The report of the study was published in the Journal of Clinical Investigation and it tells how exactly release of gut serotonin affects eventual bone mass. Apparently when gut serotonin is released into the body’s blood circulation, it immediately determines the activity of a protein coded as FoxO1.
FoxO1 is essentially a transcription factor. This means it is protein that binds to specific DNA sequences, thereby controlling the flow of genetic information from DNA to molecular RNA. (4)
Depending upon the level of serotonin released into the general circulation, FoxO1 interacts with another protein coded as CREB that promotes bone formation. It can also act with yet another protein ATF4 which prohibits or blocks the formation of bones. So we can see that fluctuations in the level of gut serotonin released can cause to promote or block the formation of bones eventually affecting our bone mass and deciding our risk factor quotient for osteopenia and osteoporosis.
Sources:
- Serotonin; The Free Medical Dictionary; Web September 2012; http://medical-dictionary.thefreedictionary.com/serotonin
- Definition of Serotonin; MedicineNet.com; Web September 2012; http://www.medterms.com/script/main/art.asp?articlekey=5468
- A Delicate Balance: Gut Serotonin And Bone Maintenance; MediLexicon; Web September 2012; http://www.medilexicon.com/medicalnews.php?newsid=249882
- Transcription Factor; Wikipedia; Web September 2012; http://en.wikipedia.org/wiki/Transcription_factor
MORE:
- More information on serotonin and bones may be had at the September 2010 issue of Journal of Clinical Endocrinology and Metabolism: http://jcem.endojournals.org/content/95/9/4124.full
- Here’s another article on how to increase brain serotonin levels without taking drugs- How to increase serotonin in the human brain without drugs; Journal of Psychiatry & Neuroscience; web September 2012; http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2077351
- FOXO1 orchestrates the bone-suppressing function of gut-derived serotonin; Journal of Clinical Investigation; Web September 2012; http://www.jci.org/articles/view/64906
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