Fig. 5.

Schematic diagram showing the relationship between KNDy neurons and the neuroendocrine circuits controlling LH secretion in postmenopausal women. Degeneration of ovarian follicles results in loss of estrogen secretion (Hansen et al., 2008). Removal of estrogen negative feedback increases LH secretion from the anterior pituitary gland into the systemic circulation. In the infundibular nucleus, there is hypertrophy of a subpopulation of neurons expressing ERα, kisspeptin, NKB and substance P mRNA accompanied by increased kisspeptin, NKB and substance P gene expression (Rance and Young, 1991; Rometo et al., 2007; Rometo and Rance, 2008; Sandoval-Guzmán et al., 2004). Neurons expressing dynorphin mRNA also exhibit neuronal hypertrophy, but the number of neurons expressing dynorphin gene transcripts is reduced (Rometo and Rance, 2008). Dual-labeled NKB/kisspeptin fibers are closely apposed to GnRH cell bodies and processes in the human medial basal hypothalamus (Hrabovszky et al., 2011). GnRH mRNA is increased in a separate subpopulation of neurons in the medial basal hypothalamus of postmenopausal women (Rance and Uswandi, 1996). Reproduced with permission from Rance (2009).