The Year in Neuroendocrinology.

At the "Year In Neuroendocrinology" session during the 2009 meeting of The Endocrine Society, I highlighted recent progress in three main areas of neuroendocrinology: neural mechanisms of action of estradiol, GnRH regulation, and epigenetics. In the area of neural mechanisms of action of estradiol, we have seen the list of estrogen receptors continue to expand and that neurosteroid synthesis is rapidly regulated by the social environment; that brain sexual differentiation can occur via the action of estradiol in upstream neurons without the need of estrogen receptors in affected neurons; and that a particular xenoestrogen can block the effects of estradiol and testosterone in brain synapses. In the area of GnRH regulation, kisspeptin continues to be a major player in reproductive endocrinology; neurokinin B should be added to the growing list of critical peptides involved in puberty and reproduction; and RFamide-related peptides have a direct role in regulation of gonadotropin-releasing neurons as a gonadotropin-inhibiting hormone. Finally, in the epigenetics field, we learned that the same principles of importance of parental care in epigenetic regulation in hippocampal glucocorticoid receptors in rats applies to humans and may explain some long-term effects of childhood abuse on the hypothalamic-pituitary-adrenal axis. It is difficult, if not impossible, to predict which findings will have an enduring impact on the field. It will be interesting to look back, 10 yr from now, to see whether the papers that were chosen were in fact well cited and whether they were influential in driving additional research in neuroendocrinology.