Salk Institute researchers Jean Rivier and Catherine Rivier were investigating how stress affects gastrointestinal function when they may have found a chemical compound that induces hair growth by blocking a stress-related hormone associated with hair loss. The discovery came entirely by accident. The team was originally studying brain-gut interactions and had been using mice that were genetically altered to overproduce a stress hormone called corticotrophin-releasing factor, or CRF. As these mice age, they lose hair and eventually become bald on their backs, making them visually distinct from their unaltered counterparts. Researchers had developed a chemical compound called astressin-B, which blocks the action of CRF, and they created an animal model of chronic stress by altering the mice to overproduce CRF. Researchers then injected the astressin-B into the bald mice to observe how its CRF-blocking ability affected gastrointestinal tract function. The initial injection had no effect, so the investigators continued the injections over five days. Then they noticed something surprising — the bald mice regrew their hair. Rivier and colleagues from The University of California, Los Angeles and the Oregon Health and Sciences University have filed for a patent on the compound and plan to set up a company to begin raising money for development and testing.