Before I go any further, I have to warn any balding individuals reading this hoping for a solution to their hair loss problems that I'm going to talk about a study in mice. Nothing—yet—has been tested in humans, so don't get too excited.
Our story starts with a group of scientists studying chronic stress and its effects on gastrointestinal tract function in mice (their report appears in PLoS ONE). They were using mice genetically engineered to produce large amounts of the stress hormone corticotrophin-releasing factor, CRF, injecting them with a peptide, astressin-B, that blocks CRF, and then seeing what effect there was on the gastrointestinal tract. A single injection had no effect, so they repeated the injections over five days. At the end of their experiment, they did some measurements on the mice's colons and put them back in their cages.
The CRF-overproducing mice don't look like any old mice, though. A side effect of having all that extra stress hormone is that they develop allopecia and lose the hair on their backs as they age. So the scientists studying chronic stress with these mice weren't expecting to find furry mice three months after their gastrointestinal study. In fact, they couldn't tell the CRF-overproducing mice apart from normal mice. "When we analyzed the identification number of the mice that had grown hair we found that, indeed, the astressin-B peptide was responsible for the remarkable hair growth in the bald mice," said study co-author Million Mulugeta of UCLA.
Repeated experiments confirmed this accidental finding; daily injections of astressin-B over five days prompted hair re-growth that lasted about four months, quite a long time for a creature that lives only two years. And the researchers also found that they could prevent hair loss in CRF-overproducing mice if they were treated with astressin-B while they were still young.
It's a long way from a miracle cure for human balding, but this research "could open new venues to treat hair loss in humans," Mulugeta said. When spray-on hair is an option, certainly there's room for improvement.