Healthy soil and sustainable growing

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Is Dirt the New Prozac?
Injections of soil bacteria produce serotonin—and happiness—in mice.
by Josie Glausiusz
http://discovermagazine.com/2007/jul/raw-data-is-dirt-the-new-prozac

THE STUDY  “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 who were injected with killed M. vaccae
reported better quality of life 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.

THE METHODS  Some studies have found that treatment with M. vaccae, the
inoffensive soil bacterium, eases skin allergies, and other reports—such
as the cancer study—show that it can improve mood. Christopher Lowry, 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.