Irisin is the so-called “exercise hormone”, and it’s been the subject of a lot of controversy since its discovery. Not everyone is convinced that it even exists in humans, and a paper earlier this year flat-out called it a myth, which is something that you don’t see very often in the scientific literature.
Now the Spiegelman group, irisin’s discoverers, have fired back. This paper reports the quantification of the hormone in circulating human blood, via fairly advanced analytical techniques, and maintains that it does indeed exist (even though its gene has a funny-looking start codon), and that its levels are increased by exercise. Here’s the press release, if you don’t have access to the paper.
So the ball has been hit back across the net – for now, it looks like irisin is in there, but you really have to bear down to see it, and that antibody-based detection is not the way to go. The tandem mass-spec method that the Spiegelman group has used here is not exactly cheap or convenient, but there’s no requirement that nature make it easy for any of us. We’ll see what the response is, and how long it takes to arrive. . .