Although male pattern baldness affects some 80% of Caucasian men by age 70, it’s remained a puzzle to scientists. Existing treatments were discovered by chance: Rogaine was originally a drug for high-blood pressure and Propecia was for prostate enlargement. In a new study, however, researchers have identified a molecule called Prostaglandin D2 (PGD2) that inhibits hair growth in men, which could provide a target for future drugs designed to treat baldness.
The first thing researchers did was find a good use for the scalp fragments, usually discarded, from men undergoing hair transplant surgery. (Well, where else do you find volunteers to get scalped?) Comparing bald and non-bald tissue from these scalp parts, they discovered that the bald scalp had ten times as much PGD2 and elevated levels of PTGDS, the enzyme that makes PGD2, compared to normal scalp. The gene for PTGDS is also expressed more when there’s lots of testosterone floating around, which may explain why baldness is so endemic to men.
Once scientists identified PGD2 as a potential culprit in baldness, trials in mice were the next step. They found that mutant mice with unusually high levels of PGD2 also had the atrophied hair follicles of bald men and grew less fur. When the researchers put PGD2 on the skin of live mice, as well as on human follicles they’d grown in a dish, they found the molecule inhibited hair growth there, too. Verdict on PGD2in the case of male pattern baldness? Guilty.
Men who object to baldness may find comfort in new treatments made possible by this discovery: Hair growth inhibition by PGD2 requires a receptor called GPR44, so knocking out this receptor could mean saying bye-bye to comb-overs.
Actual study: http://stm.sciencemag.org/content/4/126/126ra34.full