Date of Graduation


Document Type


Degree Type



Davis College of Agriculture, Natural Resources and Design


Animal and Nutritional Sciences

Committee Chair

Robert L Goodman

Committee Co-Chair

Stanley M Hileman

Committee Member

Michael W Vernon

Committee Member

Robert A Dailey

Committee Member

Steven L Hardy


Neurokinin B (NKB) and kisspeptin are critical for fertility and potent stimulators of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) secretion in sheep. We previously demonstrated that administration of NKB receptor (NK3R) agonist, senktide, within the retrochiasmatic area (RCh) resulted in surge-like release of LH and increased expression of kisspeptin neurons in the arcuate nucleus (ARC) of female lambs. We concluded that NKB-responsive neurons in the RCh stimulate GnRH secretion by inducing kisspeptin release from neurons in the ARC.

We have demonstrated morphological and functional evidence of sexual dimorphism in NKB-NK3R signaling in ovine RCh. RCh senktide administration resulted in prolonged, surge-like LH release in female, but not male sheep. This was associated with fewer NK3R-positive cells and NKB contacts onto NK3R-containing cells in the RCh, and fewer NKB and kisspeptin cells in the ARC of males. This led us to conclude that deficiencies in NKB inputs to the RCh, response to NKB in the RCh, and ability of KNDy neurons to respond to a stimulus from the RCh contribute to sex-dependent expression of the GnRH/LH surge in sheep. Additionally, we provide evidence for existence of galanin/NK3R colocalization in the RCh in females and support a role for galanin as a possible candidate for the neurotransmitter in NK3R-containing cells needed for the LH surge in this region. Based on the observation that galanin and CTβ colocalize in the RCh, NKB may stimulate NK3R-containing galanin neurons in the RCh that project to the ARC to stimulate kisspeptin release from KNDy neurons.

Included in

Endocrinology Commons