Brain complexity: brains have weight controls (Introduction)

by David Turell , Wednesday, August 22, 2018, 23:05 (2074 days ago) @ David Turell

Another one, involving satiety control:

https://medicalxpress.com/news/2018-08-destructive-mechanism-blocks-brain.html

"An international team of researchers has uncovered a destructive mechanism at the molecular level that causes a well-known phenomenon associated with obesity, called leptin resistance.

"They found that mice fed a high-fat diet produce an enzyme named MMP-2 that clips receptors for the hormone leptin from the surface of neuronal cells in the hypothalamus. This blocks leptin from binding to its receptors. This in turn keeps the neurons from signaling that your stomach is full and you should stop eating.

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"Leptin molecules are released from white fat tissue during a meal. They travel through the blood stream into the brain, specifically the hypothalamus, where they stimulate neural receptors to signal that the stomach is full. People who are obese often have plenty of leptin in their blood, but it fails to lead to signaling satiety.

"Leptin resistance is a known process associated with obesity, but the molecular mechanisms by which it occurs were not understood.

"Researchers first tested brain tissue from obese mice for protease activity. This is how they found MMP-2, the enzyme that they suspected was damaging leptin receptors. Mazor and colleagues then developed a method to tag leptin receptors to see what was happening to them.
They observed that MMP-2 was damaging the receptors, which lost their ability to signal. Researchers then used a recombinant protein to verify that the MMP-2 enzyme was indeed cleaving leptin receptors. They also cultured brain cells from mice and found clipped receptors when MMP-2 was present.

"Researchers genetically altered a group of mice to not produce MMP-2. In spite of being fed a high-fat diet, these mice gained less weight and their leptin receptors remained intact. Meanwhile, mice that were fed the same diet but were not genetically altered became obese and their leptin receptors were cleaved."

Comment: There must be complex networks of protein reactions to tell the brain when enough is enough. Obesity is a dangerous condition. There is no way chance can develop a series of controls like this. It has too many parts and must be designed.