[Strawbale] Is Dirt the New Prozac?

[Jon Van Eck]

I always thought I felt better after working with Cob...now I know why!!


http://discovermagazine.com/2007/jul/raw-data-is-dirt-the-new-prozac


Is Dirt the New Prozac?


Injections of soil bacteria produce serotonin-and happiness-in mice.


by Josie Glausiusz 

THE STUDY
<http://www.pubmedcentral.nih.gov/botrender.fcgi?blobtype=html&artid=186
8963>   "Identification of an Immune-Responsive Mesolimbocortical
Serotonergic System: Potential Role in Regulation of Emotional
Behavior," by Christopher Lowry et al., published online on March 28 in
Neuroscience.

THE MOTIVE  Some researchers have proposed that the sharp rise in asthma
and allergy cases over the past century stems, unexpectedly, from living
too clean. The idea is that routine exposure to harmless microorganisms
in the environment-soil bacteria, for instance-trains our immune systems
to ignore benign molecules like pollen or the dandruff on a neighbor's
dog. Taking this "hygiene hypothesis" in an even more surprising
direction, recent studies indicate that treatment with a specific soil
bacterium, Mycobacterium vaccae, may be able to alleviate depression.
For example, lung cancer patients
<http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_ui
ds=11899903&dopt=Citation>  who were injected with killed M. vaccae
reported better quality of life
<http://pt.wkhealth.com/pt/re/anon/abstract.00002352-200406000-00011.htm
;jsessionid=Gx9p4l2VyTJh2pnnRhYLJLyhLfMT4tsXLfLjl7vKKqFQXFqnQ1RD!-180403
6389!-949856145!8091!-1>  and less nausea and pain. Now a team of
neuroscientists and immunologists may have figured out why this works.
The bacteria, when injected into mice, activate a set of
serotonin-releasing neurons in the brain-the same nerves targeted by
Prozac <http://serendip.brynmawr.edu/bb/berman/P2S2.htm> .

THE METHODS  Some studies have found that treatment with M. vaccae, the
inoffensive soil bacterium, eases skin allergies
<http://www.ingentaconnect.com/content/bsc/cea/2006/00000036/00000009/ar
t00002> , and other reports-such as the cancer study-show that it can
improve mood. Christopher Lowry
<http://www.bris.ac.uk/neuroscience/research/groups/pidetails/35> , a
neuroscientist at the University of Bristol in England, had a hunch
about how this process might work. "What we think happens is that the
bacteria activate immune cells, which release chemicals called cytokines
that then act on receptors on the sensory nerves to increase their
activity," he says.

To verify this hypothesis, he and his colleagues carried out a series of
experiments on mice. First, Lowry killed and broke up M. vaccae with
sound waves. He then anesthetized six mice and injected the pulverized
bacteria directly into their windpipes. After killing the mice, he
indirectly measured the levels of cytokines in the animals' bodies and
found an increased production of these proteins in their lung tissue.   

The team also looked at the mouse brains to see which neurons, if any,
were activated after the bacterial injection. They found that
serotonin-producing neurons in a specific region of the brain-the dorsal
raphe nucleus-were more active in the treated mice. "That's important,"
Lowry says, "because cells in that part of the raphe project to parts of
the brain that regulate mood, including the prefrontal cortex and the
hippocampus, which is also involved in mood regulation and cognitive
function." They also found increases in serotonin itself in the
prefrontal cortex.

Finally, Lowry and his colleagues studied another set of mice, who were
subjected to a stress-response test. They dropped each mouse into water
for five minutes and timed how long it would take the animal to switch
from active swimming to passive floating. Control mice swam for an
average of two and a half minutes, while the M. vaccae-injected animals
paddled for four. Researchers already know that antidepressants increase
active swimming and decrease immobility. The bacteria "had the exact
same effect as antidepressant drugs," Lowry explains.

THE MEANING  The results so far suggest that simply inhaling M.
vaccae-you get a dose just by taking a walk in the wild or rooting
around in the garden-could help elicit a jolly state of mind. "You can
also ingest mycobacteria either through water sources or through eating
plants-lettuce that you pick from the garden, or carrots," Lowry says.

Graham Rook, an immunologist at University College London and a coauthor
of the paper, adds that depression itself may be in part an inflammatory
disorder. By triggering the production of immune cells that curb the
inflammatory reaction typical of allergies, M. vaccae may ease that
inflammation and hence depression. Therapy with M. vaccae-or with drugs
based on the bacterium's molecular components-might someday be used to
treat depression. "It's not clear to me whether the way ahead will be
drugs that circumvent the use of these bugs," Rook says, "or whether it
will be easier to say, 'The hell with it, let's use the bugs.'"