BLOOMINGTON, Ind. -- A hormone implicated in the onset of human puberty also appears to control reproductive activity in seasonally breeding rodents, report Indiana University Bloomington and University of California at Berkeley scientists in the March 2007 issue of Endocrinology. The paper is now accessible online via the journal's rapid electronic publication service.

The researchers present evidence that kisspeptin, a recently discovered neuropeptide encoded by the KiSS-1 gene, mediates the decline of male Siberian hamsters' libido and reproduction as winter approaches and daylight hours wane.

"Ours isn't the first study to link the peptide to reproduction, but it is the first to connect kisspeptin to how animals interpret seasonal cues, including day length," said IUB biologist Gregory Demas. "Kisspeptin likely plays an integral role in coordinating seasonal reproduction in a wide range of animals."

Kisspeptin joins a select few proteins believed to act as switches that connect environmental changes to a physiological response.

"This peptide is poised to act as an integrator of environmental information to allow for the optimal neuroendocrine control of reproduction in vertebrates, including humans," said UC Berkeley neuroscientist Lance Kriegsfeld. "In humans and other species, if the environment is not satisfactory, sex drive will decline; kisspeptin is likely part of the pathway responsible for this regulation."

The scientists divided a population of male Siberian hamsters (Phodopus sungorus) into treatment groups: those housed in long, summer-like photoperiods and those in short, winter-like photoperiods. In a separate experiment hamsters were also treated with exogenous injections of kisspeptin after eight weeks of either short- or long-day photoperiod exposure. At the conclusion of the experimental period, scientists analyzed the hamsters' reproductive system status, blood levels of reproductive h
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Contact: David Bricker
brickerd@indiana.edu
812-856-9035
Indiana University
28-Dec-2006