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Vertebrate reproductive science and technology
RESEARCH ARTICLE

Arcuate nucleus kisspeptin response to increased nutrition in rams

S. E. Rietema A , P. A. R. Hawken A , C. J. Scott B , M. N. Lehman C , G. B. Martin https://orcid.org/0000-0002-1905-7934 A * and J. T. Smith https://orcid.org/0000-0002-3450-9505 D E *
+ Author Affiliations
- Author Affiliations

A School of Agriculture and Environment, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia.

B School of Biomedical Sciences, Charles Sturt University, Boorooma Street, Wagga Wagga, NSW 2678, Australia.

C Brain Health Research Institute and Department of Biological Sciences, Kent State University, PO Box 5190, Kent, OH 44242-0001, USA.

D The School of Human Sciences, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia.

E Corresponding author. Email: jeremy.smith@uwa.edu.au

Reproduction, Fertility and Development 31(11) 1682-1691 https://doi.org/10.1071/RD19063
Submitted: 18 February 2019  Accepted: 16 June 2019   Published: 12 September 2019

Abstract

Rams respond to acute nutritional supplementation by increasing the frequency of gonadotrophin-releasing hormone (GnRH) pulses. Kisspeptin neurons may mediate the effect of environmental cues on GnRH secretion, so we tested whether the ram response to nutrition involves activation of kisspeptin neurons in the arcuate nucleus (ARC), namely kisspeptin, neurokin B, dynorphin (KNDy) neurons. Rams were given extra lupin grain with their normal ration. Blood was sampled before feeding, and continued until animals were killed for collection of brain tissue at 2 or 11 h after supplementation. In supplemented rams, LH pulse frequency increased after feeding, whereas control animals showed no change. Within the caudal ARC, there were more kisspeptin neurons in supplemented rams than in controls and a higher proportion of kisspeptin cells coexpressed Fos, regardless of the time the rams were killed. There were more Fos cells in the mid-ARC and mid-dorsomedial hypothalamus of the supplemented compared with control rams. No effect of nutrition was found on kisspeptin expression in the rostral or mid-ARC, or on GnRH expression in the preoptic area. Kisspeptin neurons in the caudal ARC appear to mediate the increase in GnRH and LH production due to acute nutritional supplementation, supporting the hypothesised role of the KNDy neurons as the pulse generator for GnRH.

Additional keywords: energy balance, fertility, neuroendocrinology, reproduction.


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