Biological complexity: the brain helps burn fat (Introduction)

by David Turell , Saturday, January 28, 2017, 15:47 (2856 days ago) @ David Turell

The brain seems to get mixed up in all sorts of activities besides thinking, fighting infections and now burning fat:

https://www.sciencedaily.com/releases/2017/01/170127142411.htm

"Biologists at The Scripps Research Institute (TSRI) have identified a brain hormone that appears to trigger fat burning in the gut. Their findings in animal models could have implications for future pharmaceutical development.

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"Previous studies had shown that the neurotransmitter serotonin can drive fat loss. Yet no one was sure exactly how. To answer that question, Srinivasan and her colleagues experimented with roundworms called C. elegans, which are often used as model organisms in biology. These worms have simpler metabolic systems than humans, but their brains produce many of the same signaling molecules, leading many researchers to believe that findings in C. elegans may be relevant for humans.

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"This process of elimination led them to a gene that codes for a neuropeptide hormone they named FLP-7 (pronounced "flip 7").

"Interestingly, they found that the mammalian version of FLP-7 (called Tachykinin) had been identified 80 years ago as a peptide that triggered muscle contractions when dribbled on pig intestines. Scientists back then believed this was a hormone that connected the brain to the gut, but no one had linked the neuropeptide to fat metabolism in the time since.

"The next step in the new study was to determine if FLP-7 was directly linked to serotonin levels in the brain. Study first author Lavinia Palamiuc, a TSRI research associate, spearheaded this effort by tagging FLP-7 with a fluorescent red protein so that it could be visualized in living animals, possible because the roundworm body is transparent. Her work revealed that FLP-7 was indeed secreted from neurons in the brain in response to elevated serotonin levels. FLP-7 then traveled through the circulatory system to start the fat burning process in the gut.

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"Altogether, the newly discovered fat-burning pathway works like this: a neural circuit in the brain produces serotonin in response to sensory cues, such as food availability. This signals another set of neurons to begin producing FLP-7. FLP-7 then activates a receptor in intestinal cells, and the intestines begin turning fat into energy."

Comment: the caloric value of fat is about twice that of carbohydrates and proteins, but it is the fat stored in our bodies that we burn if there is a shortage of energy supply from the food we eat. Our bodies cannot afford to break down carbs and protein of our bodies' structures. As exercise increases energy must come from stored fat. But during evolution food wasn't always easily obtained, so an interesting mechanism appeared: if starving (what we call dieting) our basal metabolism (the cost of daily living at rest) reduced itself, by as much as 300 calories a day. Thus fat is naturally resistant to burning. Fascinating that the brain is geared to step in and prompt fat to burn, as another example of feedback controls in the biology of the body. Again, for me, all of this requires meticulous planning, not chance development. What is apparent is that the brain is automatically managing body processes without our conscious input. Not by chance.