The release of LH is under regulation by the neurohormone gonadotropin releasing hormone (GnRH). Recently, the peptide kisspeptin (KP) which signals through a G-protein coupled receptor, GPR54, was found to be a key component in the regulation of GnRH. Evidence for a direct role for KP at the level of the GnRH neuron comes from anatomical and in vitro studies in GnRH expressing cell lines. Two principal populations of KP neurons are described in the hypothalamus: one in the arcuate nucleus (AN) and one in a region of the preoptic area, the AVPV. The AVPV KP neurons project directly to GnRH neurons and stimulate GnRH neurons at the time of the estrogen induced LH surge, while the AN population is implicated in negative feedback. This proposal will explore the role of estrogen in the neuroendocrine regulation of the gonadotropin surge in three aims.
Aim 1 will determine if the negative and positive feedback actions of estradiol (E2) are mediated by activation of ERa in KP neurons. The responses of KP cell-specific ERa knockout (KERaKO) mice to treatments that evoke negative and positive feedback actions on LH neurosecretion will be assessed using a newly developed microdialysis system.
Aim 2 will determine if prenatal androgen exposure (PNA), which induces features of polycystic ovary disease, programs resistance to E2 feedback actions in KP neurons. KP cell-specific AR null mutant (KARKO) mice will be generated and proposed studies will determine if they are refractory to androgenic programming of altered negative and positive feedback actions of E2.
Aim 3 will determine the role of E2 in modulating KP GPR54 signaling in the regulation of the GnRH neuron. To determine if GPR54 activation in GnRH neurons mediates the physiological regulation of GnRH expression by KP neurons, the responsiveness of GnRH neuron-specific GPR54 knockout (GnRH-GPR54KO) mice to E2 negative and positive feedback actions will be assessed. The role of ER? in mediating E2 negative feedback and KP mediated synthesis and secretion of GnRH will be determined. Overall, these studies will provide a systematic, hierarchical assessment of the effects of E2 in the neuroendocrine control of the gonadotropin surge, and determine the mechanisms by which early androgen exposure may program resistance to E2 feedback actions.
This proposal will delineate both the role of kisspeptin-GPR54 signaling in estrogen feedback regulation and its locus in the central reproductive axis. It will further examine the significance of androgenic programming of altered feedback of estrogen. The outcome will be a systematic assessment of the role of kisspeptin and sex steroids on pubertal development and reproductive competence in mammals.
|Dubois, Sharon L; Wolfe, Andrew; Radovick, Sally et al. (2016) Estradiol Restrains Prepubertal Gonadotropin Secretion in Female Mice via Activation of ERÎ± in Kisspeptin Neurons. Endocrinology 157:1546-54|
|Kurian, Joseph R; Louis, Somaja; Keen, Kim L et al. (2016) The Methylcytosine Dioxygenase Ten-Eleven Translocase-2 (tet2) Enables Elevated GnRH Gene Expression and Maintenance of Male Reproductive Function. Endocrinology 157:3588-603|
|Novaira, Horacio J; Graceli, J B; Capellino, S et al. (2016) Development and Characterization of Novel Rat Anti-mERÎ² Sera. Endocrinology 157:2844-52|
|Hoffman, Gloria E; Murphy, Kelley J; Sita, Luciane V (2016) The Importance of Titrating Antibodies for Immunocytochemical Methods. Curr Protoc Neurosci 76:2.12.1-2.12.37|
|Salehi, Sajad; Adeshina, Ikeoluwa; Chen, Haolin et al. (2015) Developmental and endocrine regulation of kisspeptin expression in mouse Leydig cells. Endocrinology 156:1514-22|
|Dubois, Sharon L; Acosta-MartÃnez, Maricedes; DeJoseph, Mary R et al. (2015) Positive, but not negative feedback actions of estradiol in adult female mice require estrogen receptor Î± in kisspeptin neurons. Endocrinology 156:1111-20|
|Bethea, Cynthia L; Reddy, Arubala P; Flowers, Matthew et al. (2015) High fat diet decreases beneficial effects of estrogen on serotonin-related gene expression in marmosets. Prog Neuropsychopharmacol Biol Psychiatry 58:71-80|
|Song, Woo-Jin; Mondal, Prosenjit; Wolfe, Andrew et al. (2014) Glucagon regulates hepatic kisspeptin to impair insulin secretion. Cell Metab 19:667-81|
|Wu, Sheng; Divall, Sara; Nwaopara, Amanda et al. (2014) Obesity-induced infertility and hyperandrogenism are corrected by deletion of the insulin receptor in the ovarian theca cell. Diabetes 63:1270-82|
|Wolfe, Andrew; Divall, Sara; Wu, Sheng (2014) The regulation of reproductive neuroendocrine function by insulin and insulin-like growth factor-1 (IGF-1). Front Neuroendocrinol 35:558-72|
Showing the most recent 10 out of 23 publications