American Society for Microbiology
Summary:
Over
the last half decade, it has become increasingly clear that the normal
gastrointestinal (GI) bacteria play a variety of very important roles in
the biology of human and animals. Now researchers propose yet another
role for GI bacteria: that they exert some control over their hosts'
appetites.
the last half decade, it has become increasingly clear that the normal
gastrointestinal (GI) bacteria play a variety of very important roles in
the biology of human and animals. Now researchers propose yet another
role for GI bacteria: that they exert some control over their hosts'
appetites.
Are
bacteria making you hungry? Over the last half decade, it has become
increasingly clear that the normal gastrointestinal (GI) bacteria play a
variety of very important roles in the biology of human and animals.
bacteria making you hungry? Over the last half decade, it has become
increasingly clear that the normal gastrointestinal (GI) bacteria play a
variety of very important roles in the biology of human and animals.
Over
the last half decade, it has become increasingly clear that the normal
gastrointestinal (GI) bacteria play a variety of very important roles in
the biology of human and animals. Now Vic Norris of the University of
Rouen, France, and coauthors propose yet another role for GI bacteria:
that they exert some control over their hosts' appetites. Their review
was published online ahead of print in the Journal of Bacteriology.
the last half decade, it has become increasingly clear that the normal
gastrointestinal (GI) bacteria play a variety of very important roles in
the biology of human and animals. Now Vic Norris of the University of
Rouen, France, and coauthors propose yet another role for GI bacteria:
that they exert some control over their hosts' appetites. Their review
was published online ahead of print in the Journal of Bacteriology.
This
hypothesis is based in large part on observations of the number of
roles bacteria are already known to play in host biology, as well as
their relationship to the host system. "Bacteria both recognize and
synthesize neuroendocrine hormones," Norris et al. write. "This has led
to the hypothesis that microbes within the gut comprise a community that
forms a microbial organ interfacing with the mammalian nervous system
that innervates the gastrointestinal tract." (That nervous system
innervating the GI tract is called the "enteric nervous system." It
contains roughly half a billion neurons, compared with 85 billion
neurons in the central nervous system.)
"The gut microbiota
respond both to both the nutrients consumed by their hosts and to the
state of their hosts as signaled by various hormones," write Norris et
al. That communication presumably goes both ways: they also generate
compounds that are used for signaling within the human system,
"including neurotransmitters such as GABA, amino acids such as tyrosine
and tryptophan -- which can be converted into the mood-determining
molecules, dopamine and serotonin" -- and much else, says Norris.
Furthermore,
it is becoming increasingly clear that gut bacteria may play a role in
diseases such as cancer, metabolic syndrome, and thyroid disease,
through their influence on host signaling pathways. They may even
influence mood disorders, according to recent, pioneering studies, via
actions on dopamine and peptides involved in appetite. The gut
bacterium, Campylobacter jejuni, has been implicated in the induction of anxiety in mice, says Norris.
But
do the gut flora in fact use their abilities to influence choice of
food? The investigators propose a variety of experiments that could help
answer this question, including epidemiological studies, and
"experiments correlating the presence of particular bacterial
metabolites with images of the activity of regions of the brain
associated with appetite and pleasure."
hypothesis is based in large part on observations of the number of
roles bacteria are already known to play in host biology, as well as
their relationship to the host system. "Bacteria both recognize and
synthesize neuroendocrine hormones," Norris et al. write. "This has led
to the hypothesis that microbes within the gut comprise a community that
forms a microbial organ interfacing with the mammalian nervous system
that innervates the gastrointestinal tract." (That nervous system
innervating the GI tract is called the "enteric nervous system." It
contains roughly half a billion neurons, compared with 85 billion
neurons in the central nervous system.)
"The gut microbiota
respond both to both the nutrients consumed by their hosts and to the
state of their hosts as signaled by various hormones," write Norris et
al. That communication presumably goes both ways: they also generate
compounds that are used for signaling within the human system,
"including neurotransmitters such as GABA, amino acids such as tyrosine
and tryptophan -- which can be converted into the mood-determining
molecules, dopamine and serotonin" -- and much else, says Norris.
Furthermore,
it is becoming increasingly clear that gut bacteria may play a role in
diseases such as cancer, metabolic syndrome, and thyroid disease,
through their influence on host signaling pathways. They may even
influence mood disorders, according to recent, pioneering studies, via
actions on dopamine and peptides involved in appetite. The gut
bacterium, Campylobacter jejuni, has been implicated in the induction of anxiety in mice, says Norris.
But
do the gut flora in fact use their abilities to influence choice of
food? The investigators propose a variety of experiments that could help
answer this question, including epidemiological studies, and
"experiments correlating the presence of particular bacterial
metabolites with images of the activity of regions of the brain
associated with appetite and pleasure."
Story Source:
The above story is based on materials provided by American Society for Microbiology. Note: Materials may be edited for content and length.
The above story is based on materials provided by American Society for Microbiology. Note: Materials may be edited for content and length.
Journal Reference:
Cite This Page:- V. Norris, F. Molina, A. T. Gewirtz. Hypothesis: bacteria control host appetites. Journal of Bacteriology, 2012; DOI: 10.1128/JB.01384-12
American
Society for Microbiology. "Are bacteria making you hungry?."
ScienceDaily. ScienceDaily, 19 December 2012.
<www.sciencedaily.com/releases/2012/12/121219142301.htm>.
Society for Microbiology. "Are bacteria making you hungry?."
ScienceDaily. ScienceDaily, 19 December 2012.
<www.sciencedaily.com/releases/2012/12/121219142301.htm>.
