Kisspeptin: Past, Present, and Prologue - Kisspeptin Signaling in Reproductive Biology - page 2

Chapter 1
Kisspeptin: Past, Present, and Prologue
Robert A. Steiner
Abstract Research in the nineteenth and early twentieth century established that
the brain awakens reproduction, governs reproductive activity in the adult of virtually
all vertebrates. By 1950, nearly 100 years later, scientists realized that the hypo-
thalamus and its neurosecretory products play a key role in regulating gonadal func-
tion in both males and females. Another 20 years would be required to reveal the
chemical identity of GnRH and establish that neurons producing GnRH represent
the fi nal common pathway through which the brain regulates gonadotropin secre-
tion. It had also become clear that GnRH neurons behave more like motor neu-
rons—better perhaps at going than stopping—and are themselves regulated by a
complex network of afferent inputs, which guide the tempo of sexual maturation,
regulate estrous and menstrual cycles, control seasonal breeding, and stop reproduc-
tion under adversity. In 2003, the revelation that kisspeptin and its receptor are criti-
cal for reproduction opened a fl oodgate of research documenting the role of
kisspeptin neurons as central processors of reproduction. Today, there is wide con-
sensus that kisspeptin signaling in the brain is essential, providing the impetus to
GnRH neurons to awaken at puberty and reigning the activity of these neurons
when discretion is advised. We celebrate this watershed moment—with full knowl-
edge that time and discovery will provide context and perspective to even these
heady days.
In the autumn of 1848, A.A. Berthold fi xed his eye upon two sad roosters. The
German physiologist had castrated the young cockerels some months earlier, after
which their tail feathers were lost, their combs had yellowed and drooped, their voices
became monotonic, and the creatures grew disinterested in chasing hens. Berthold
had castrated four other roosters at the same time as the fi rst two, but in these animals,
R. A. Steiner ( )
Department of Physiology and Biophysics, University of Washington,
Box 357290 , Seattle , WA , 98195 , USA
e-mail: [e-mail]