By Dov Michaeli
Volumes upon volumes of research articles have been published on the effects of exercise on health. It is common knowledge that exercise facilitates weight loss, reduces LDL cholesterol and triglycerides, and increases insulin sensitivity. Results: lower rates of heart disease and type 2 diabetes. So what else remains to said about the subject? Turns out, we still didn’t know something very critical.
When a muscle exercises the level of a protein called PGC-1α is elevated. This protein regulates metabolic genes in skeletal muscle and contributes to the response of muscle to exercise. For instance, one of the striking effects of this protein is an increase in the number of mitochondria, the powerhouses of the cell, in the muscle. Glucose is metabolized in the mitochondria, providing the energy necessary for muscle activity in the form of ATP.
From here, the usual description of the benefits of exercise skip to other tissues. The adipose (fat) cells mobilize the stored fat and deliver triglycerides to the liver, where they are broken down to provide more energy stored in the ATP molecules. Cells taking up glucose for needed energy to perform their functions need insulin to facilitate the uptake. Exercise increases the sensitivity of the insulin receptor so that less of the hormone is needed; in type 2 diabetes, more insulin is required because of reduced sensitivity of the insulin receptor.
But we blithely skipped over a crucial step: how does the muscle influence other tissues to do all these good things? The reason for the omission is simple: we didn’t know. That is, until a recent paper published in Cell metabolism came up with a surprisingly simple answer.
Robert Gerszten of Massachussetts General Hospital in Boston and his colleagues found that when they forced the expression of the protein PGC-1∝, metabolites — including BAIBA — were then released from muscle cells into the circulation. What on earth is BAIBA? It stands for beta amino isobutyric acid. This particular molecule increases the expression of calorie-burning genes in fat cells. In addition, rising levels of BAIBA during exercise was associated with benefits to triglyceride, fasting blood sugar and total cholesterol levels. In short, all the metabolic good things we get from exercising.
What is surprising is that BAIBA is a very simple molecule. Anybody who took a rudimentary course in organic chemistry would have no trouble synthesizing it.
Apart from the shear pleasure of solving the puzzle of the widespread effects of exercise throughout the body, this discovery opens the door to a novel approach to treatment of obesity and type 2 diabetes.
But if you think this is the holy grail of couch potatoes -all the gain and no pain, I think you are in for a disappointment. Our bodies are complex, made up of redundant systems to ensure our survival. Thus, the effects of exercise are myriad, the molecules that mediate these effects are many -no one molecule does it all. So go out, exercise, and think about good old BAIBA.