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Neurokinin‐3 Receptor Activation in the Retrochiasmatic Area is Essential for the Full Pre‐Ovulatory Luteinising Hormone Surge in Ewes
Author(s) -
Porter K. L.,
Hileman S. M.,
Hardy S. L.,
Nestor C. C,
Lehman M. N.,
Goodman R. L.
Publication year - 2014
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1111/jne.12180
Subject(s) - endocrinology , medicine , agonist , neurokinin b , preoptic area , biology , receptor , hypothalamus , secretion , estrous cycle , chemistry , substance p , neuropeptide
Neurokinin B ( NKB ) is essential for human reproduction and has been shown to stimulate luteinising hormone ( LH) secretion in several species, including sheep. Ewes express the neurokinin‐3 receptor ( NK 3R) in the retrochiasmatic area (RCh) and there is one report that placement of senktide, an NK 3R agonist, therein stimulates LH secretion that resembles an LH surge in ewes. In the present study, we first confirmed that local administration of senktide to the RC h produced a surge‐like increase in LH secretion, and then tested the effects of this agonist in two other areas implicated in the control of LH secretion and where NK 3R is found in high abundance: the preoptic area ( POA ) and arcuate nucleus ( ARC ). Bilateral microimplants containing senktide induced a dramatic surge‐like increase in LH when given in the POA similar to that seen with RC h treatment. By contrast, senktide treatment in the ARC resulted in a much smaller but significant increase in LH concentrations suggestive of an effect on tonic secretion. The possible role of POA and RC h NK 3R activation in the LH surge was next tested by treating ewes with SB 222200, an NK 3R antagonist, in each area during an oestradiol‐induced LH surge. SB 222200 in the RC h, but not in the POA , reduced the LH surge amplitude by approximately 40% compared to controls, indicating that NK 3R activation in the former region is essential for full expression of the pre‐ovulatory LH surge. Based on these data, we propose that the actions of NKB in the RC h are an important component of the pre‐ovulatory LH surge in ewes.