WEDNESDAY, June 4 (HealthDay News) -- Your nerves, rather than
your eating habits, may have a more direct role in whether you are
fat or thin, according to new research.
A study on worms shows that serotonin levels in the nervous
system influence feeding and fat. Serotonin, a neurotransmitter,
also acts independently to control eating and what your body does
with those calories once they've been consumed, the study said.
"It says that the nervous system is a key regulator coordinating
all energy-related processes through distinct molecular pathways,"
Kaveh Ashrafi, of the University of California, San Francisco, said
in a prepared statement. "The nervous system makes a decision about
its state leading to effects on behavior, reproduction, growth and
metabolism. These outputs are related, but they are not
consequences of each other. It's not that feeding isn't important,
but the neural control of fat is distinct from feeding."
Ashrafi said that given serotonin's ancient evolutionary
origins, you can apply what's learned from the worms to humans.
"From a clinical perspective, this may mean you could develop
therapeutic strategies to manipulate fat metabolism independently
of what you eat," he said. "Now, the focus is primarily on feeding
behavior. As important as that is, it's only part of the story. If
the logic of the system is conserved across species, a strategy
that focuses solely on behavior can only go so far. It may be one
reason diets fail."
The findings were published in the June issue of
Cell Metabolism.
At its most basic level, fat regulation is the balance between
energy intake and expenditure; however, Ashrafi said the physiology
is very complicated.
In the worms, serotonin affected feeding by involving nerve
receptors not normally required for fat control. The byproducts of
the signaling process ended up affecting the control of feeding
behavior, Ashrafi said.
In the worms and in mammals, high serotonin levels are
associated with fat reduction, while low serotonin levels lead to
fat accumulation, the researchers noted. However, in the worms,
when serotonin goes up, the worms desire to eat increases even as
fat melts away. But in humans, high serotonin leads people to eat
less and shed fat.
Serotonin's effects on fat and eating habits in the worms fit
the nerve messenger's role as a sensory gauge of nutrient
availability, the researchers said. When resources are scarce,
worms build up their fat reserves and switch metabolic gears to
save energy and direct nutrients to fat stores.
Ashrafi said serotonin's role in balancing energy across species
leads him to believe that "human counterparts of
feeding-independent fat regulatory genes identified in our study
may similarly regulate energy balance."
More information
The U.S. National Library of Medicine has more about
serotonin.
