Rugged, tough and a TV idol. But if he was a real man he would not be bald

The myth that bald men are more sexy is being challenged by new findings which blame a shiny pate on an excess of a female hormone.

American scientists say that high levels of oestrogen trigger hair loss in men and not, as the balding had encouraged women to believe, the elevated levels of male hormones surging through their veins. The experimental evidence for the theory is so far limited to bald mice, but already there is talk of the huge financial potential for a reliable cure for follicularly challenged males using oestrogen-blocking drugs.

Up to 8 million men in Britain suffer from some degree of baldness and, according to psychologists, "feel more depressed, are more unsociable and feel much less attractive as a result". Many are desperate to retain or replace their less-than-flowing locks, and spend up to pounds 100m a year on "cures".

Current treatments - ranging from the hair implants favoured by Elton John and Graham Gooch to a Japanese shampoo which must be applied while listening to Mozart - are of doubtful value.

More bizarre yet is the "inverter", a machine which enables bald men to hang upside down to improve blood flow to the scalp. But even this must be preferable to rubbing Baby Bio, Marmite, or curry spices -all of which have been touted as cures - on your head.

The new compound under investigation is known only as 182780, and is being developed by Zeneca Pharmaceuticals as a treatment for advanced breast cancer. While carrying out laboratory trials, Robert Smart and colleagues at North Carolina State University noticed that mice which had been shaved for tests using compound 182780 developed a lush, new growth of hair. The mice treated with oestrogen however, remained hairless.

According to a report in the Proceedings of the National Academy of Sciences, an American journal, Dr Smart found that the effect of oestrogen was to halt the development of hair follicles, producing a "profound and prolonged inhibition of hair growth".

Dr Smart concluded that the follicles contained oestrogen receptors, sensitive to the presence or absence of the hormone, and extended the hypothesis to suggest that excess oestrogen triggered baldness or alopecia.

Dermatologists have given a tentative welcome to the findings, but point out that there is a big difference between a shaved mouse and a bald man. A spokesman for Zeneca described it as "very, very, preliminary research".

There is only one licensed prescription medicine for baldness available in Britain, called Regaine, a drug used to treat blood pressure. Like compound 182780, it was found to have an interesting side-effect. The manufacturers claim that it will stop hair loss in four out of five men.