Will the wonders of oxytocin never cease? I missed this February report from a bowling team's worth of scientists, led by Roberto Tamma of the University of Bari. In Oxytocin is an anabolic bone hormone, they say that oxytocin builds bones, while blocking oxytocin causes osteoporosis in mice. It's complicated, read the abstract if you want more.
It's interesting that they write that oxytocin was "hitherto thought solely to modulate lactation and social bonding." Because, up until a couple of years ago, the story was, "oxytocin, formerly thought to solely modulate lactation."
The research was mentioned by the fantastic NY Times science writer Natalie Angier. Bones are highly responsive to oxytocin and serotonin, the latter specifically from the gut, she says poetically. "... bone quickens to the touch of serotonin and oxytocin, signaling molecules more often associated with happy moods, friendship and cuddling together in a straw nest than with the integrity of the backbone."