Pharmaceutical giant Roche is experimenting with a new variation of the muscle-strengthening hormone IGF-1. Researchers at Roche will soon publish the results of a study that show that PEG-IGF-1 has fewer side effects that the regular IGF-1. And it probably helps chemical athletes achieve even better results too.
In August 2010 United States Application US20100210547 appeared, Roche’s patent on a new IGF-1 analogue. [US20100210547] Right after this the researchers submitted an article to the Journal of Biological Chemistry on the tests they had done with PEG-IGF-1 on cells and mice.
The structural formula of PEG-IGF-1 is shown above. The difference with regular IGF-1 is that the PEg-IGF molecule on lysine 68 is PEGylated. This means that a chain of polyethylene glycol units is attached to this location on the chain. The researchers discovered that this what gives PEG-IGF-1 other pharmacological properties.
One of IGF-1’s undesirable effects is that it can reduce sugar levels dramatically. This is because IGF-1 imitates the effect of insulin: IGF-1 has its own receptor, but can also attach itself to the insulin receptor. The figure below shows that PEG-IGF-1 doesn’t attach as easily to the insulin A and B receptor as IGF-1 does.
PEG-IGF-1 has the same effect on the muscle cells’ glucose uptake as IGF-1 does. But PEG-IGF-1 results in less glucose uptake by fat cells than IGF-1. Incidentally, the researchers regard this as confirmation of a new theory: that IGF-1 is not as important for muscle cells as was previously thought, and that they require IGF-1 above all for the regulation of glucose uptake.
PEG-IGF-1 is not quite as good a ligand for the IGF-1 receptor as IGF-1 itself. But on the other hand, PEG-IGF-1 remains present for longer in the body, the researchers discovered when they injected mice with this substance. After injecting regular IGF-1, the hormone has almost disappeared from the system after 6 hours, while PEG-IGF-1 has hardly declined even after 48 hours.