J. Exp. Med. doi:10.1084/jem.20091924 (2010)

Male sex hormones may help men but not women to recover from cardiovascular problems.

Daniel Sieveking and Martin Ng of the University of Sydney in Australia and their group exposed the cells that line human blood vessels to dihydrotestosterone (DHT), a potent natural hormone that is synthesized from and acts like testosterone. DHT caused the cells from males, but not females, to form vessel-like structures — an indicator of tissue repair.

Neutered mice had a tougher time growing blood vessels in an implanted tissue-like gel than normal mice, with males more affected than females. This effect was reversed in the males by DHT administration, but not in females. Moreover, after the authors removed a major artery in males to restrict blood supply to the hindlimbs, the castrated mice showed poorer recovery of blood flow than those receiving a sham treatment — an effect that was also reversed by DHT.