Neurokinin B regulates reproduction via inhibition of kisspeptin in a teleost, the striped bass.
Kisspeptin and neurokinin B (NKB) are neuropeptides co-expressed in the mammalian hypothalamus and coordinately control GnRH signaling. We have found that Nkb and kisspeptin neurons are distinct in the teleost, striped bass (STB) and capitalized on this phenomenon to study the mode of action of Nkb and its related neuropeptide-F (Nkf), both of which are encoded by thetac3gene.In vitrobrain slices andin vivoadministration studies revealed that Nkb/f consistently downregulatedkiss2, whereas antagonist (AntD) administration restored this effect. Overall, a minor effect was noted ongnrh1expression, whereas Gnrh1 content in the pituitaries was reduced after Nkb/f treatment and increased with AntD. Concomitantly, immunostaining demonstrated that hypothalamic Nkb neurons border and densely innervate the largest kiss2 neuronal population in the hypothalamus, which also coexpresses Nkb receptor. No expression of Nkb receptor or Nkb neuronal projections was detected near/in Gnrh1 soma in the preoptic area. At the level of the pituitary, however, the picture was more complex: both Nkb/f and AntD upregulatedlhbandfshbexpression and Lh secretionin vivoTogether with the stimulatory effect of Nkb/f on Lh/Fsh secretion from pituitary cells,in vitro, this may indicate an additional independent action of Nkb/f within the pituitary, in which the hypothalamic pathway is more dominant. The current study demonstrates that Nkb/f utilizes multiple pathways to regulate reproduction in the STB and that in the brain, Nkb mainly acts as a negative modulator of kiss2 to regulate the release of Gnrh1.
Department of Marine BiotechnologyInstitute of Marine and Environmental Technology, University of Maryland Baltimore County, Baltimore, Maryland, USA nzmora@umbc.edu zohar@umbc.edu.
Nilli
N
Zmora
Department of Marine BiotechnologyInstitute of Marine and Environmental Technology, University of Maryland Baltimore County, Baltimore, Maryland, USA.
Ten-Tsao
TT
Wong
Department of Marine BiotechnologyInstitute of Marine and Environmental Technology, University of Maryland Baltimore County, Baltimore, Maryland, USA.
John
J
Stubblefield
Department of Animal SciencesFaculty of Agriculture, Food and Environment, The Hebrew University, Rehobot, Israel.
Berta
B
Levavi-Sivan
Department of Marine BiotechnologyInstitute of Marine and Environmental Technology, University of Maryland Baltimore County, Baltimore, Maryland, USA nzmora@umbc.edu zohar@umbc.edu.
Yonathan
Y
Zohar
D000818:Animals; D001492:Bass / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology*; D059648:Kisspeptins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008297:Male; D015287:Neurokinin B / Q000235:genetics / Q000502:physiology*; D010902:Pituitary Gland / Q000378:metabolism; D012098:Reproduction / Q000502:physiology*
D018076:DNA, Complementary; D059648:Kisspeptins; D015287:Neurokinin B
Gnrh; gonadotropes; neuroanatomy; neuropeptides; reproductive axis