Hypothalamic kisspeptin (KP) neurons are key players in the neuronal network that
regulates the onset of puberty and the pulsatile secretion of gonadotropin-releasing
hormone (GnRH). In various mammalian species, the majority of KP-synthesizing neurons
are concentrated in two distinct cell populations in the preoptic region and the arcuate
nucleus (ARC). While studies of female rodents have provided evidence that preoptic
KP neurons play a critical sex-specific role in positive estrogen feedback, KP neurons
of the ARC have been implicated in negative sex steroid feedback and they have also
been hypothesized to contribute to the pulse generator network which regulates episodic
GnRH secretion in both females and males. Except for relatively few morphological
studies available in monkeys and humans, our neuroanatomical knowledge of the hypothalamic
KP systems is predominantly based on observations of laboratory species which are
phylogenetically distant from the human. This review article discusses the currently
available literature on the topographic distribution, network connectivity, neurochemistry,
sexual dimorphism, and aging-dependent morphological plasticity of the human hypothalamic
KP neuronal system.
