In all mammalian species so far studied the first neuroendocrine manifestation of puberty is a diurnal increase in pulsatile GnRH and hence LH release [reviewed in 2]. This mode of GnRH secretion has been postulated to be driven by a subset of ARC neurons, called KNDy neurons 33, 34, because they produce Kisspeptin, NKB and Dynorphin 33. Since kisspeptin and NKB work coordinately within the population of KNDy neurons to stimulate GnRH secretion, their encoding genes (Kiss1 and Tac2) can be considered as components of a unique class of puberty-activating genes. Using Kiss1 as a prototype of this class, we carried out studies to determine if Cbx7 and Eed are expressed in kisspeptin neurons of the ARC. Double fluorescent in situ hybridization (Fig. 4a) and single-cell PCR (Fig. 4b) of eGFP-tagged kisspeptin neurons 35 showed that these neurons contain both Eed and Cbx7 mRNAs.
