

Scientists Confirm Leptin Link to Sexual
Maturity in SwineBy Jill Lee January 7, 1999Leptin, a protein long associated with obesity and its control, has also
been linked to sexual maturity in female mammals. Now scientists with the
Agricultural Research Service and the
University of Georgia have even stronger
evidence that leptin helps cue reproduction in swine. ARS is the chief
scientific wing of the U.S. Department of
Agriculture. ARS and university researchers in Athens, Ga., found estrogen triggers
leptin production by fat cells when pigs reach reproductive age. The study also
suggests leptin stimulated the brain and pituitary gland to produce two
hormones that allow pigs to ovulate. The scientists studied female pigs at 90, 150 and 210 days of age. Only the
pigs at 210 days of age--the ones on the verge of reproductive
age--demonstrated the estrogen effect. Estrogen in those pigs caused a
two-and-a-half fold increase in messenger RNA for leptin. So what do these results mean? Leptin is secreted by fat cells. In obesity
research, scientists think leptin is the body cue that enough food has been
eaten. In reproduction, leptin may send the brain a message that there is
enough energy--in the form of fat--to start reproduction. It may be that estrogen is a first cue of sexual maturity and triggers
leptin increases, which in turn tell the brain and the pituitary gland to
release those key reproductive hormones. If further research confirms these scenarios, it might be possible to speed
sexual maturity in pigs. Sows that have more piglets in their lifetime give
pork producers more profit. Researchers caution, however, that these biological chemicals are part of a
natural balance. They found a threshold where increased leptin no longer speeds
sexual maturity. And it may be that diet alone could turn on leptins
benefits sooner for farmers. Scientific contact: C. Richard Barb, ARS
Animal Physiology
Research Unit, Russell Research Center, Athens, Ga., phone (706) 546-3226,
fax: (706) 546-3586, [email protected] Story contacts Animal Physiology Research U.S. Department of Agriculture | |