Mouse researchers conducting stress hormone experiments have stumbled onto a surprising new discovery — a potential treatment for hair loss.

Scientists at UCLA and the Department of Veterans Affairs were working with genetically altered mice that typically develop head-to-tail baldness as a result of overproducing a stress hormone.

The experiment wasn’t focused on hair loss. Instead, it was designed to study a chemical compound that blocks the effects of stress on the gut. The researchers treated the bald mice for five days with the compound and then returned them to the cages, where they scampered about with several furry mice from a control group.

Three months later, the scientists went back to the cage to conduct additional experiments. They were surprised by what they saw inside — all of the mice had full heads and backs of hair. The once-bald mice, eventually identified through ear tags, were indistinguishable from their normal, furry cage mates.

Dr. Million Mulugeta, co-director of the preclinical stress biology program at UCLA, said he looked inside the cage and at first wondered why the bald mice weren’t there.

“We went back to our data log, and we realized all the mice had grown hair. It was a totally unexpected finding,” he said.

The serendipitous discovery was reported Wednesday in the online medical journal PLoS One.

Already the research is drawing a mixed response from dermatologists and hair-loss researchers.

Dr. Melissa Piliang, a dermatologist at the Cleveland Clinic, cautioned that the findings of a mouse study may not be applicable to humans, but she said that the results may spur more study of the role stress might play in human hair loss.