Age-related alterations in hypothalamic kisspeptin
 neurokinin B
 and dynorphin neurons and in pulsatile LH release in female and male rats

Yuyu Kunimura
Kinuyo Iwata
Akihito Ishigami
Hitoshi Ozawa

Pulsatile secretion of gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) decreases during aging. Kisspeptin (encoded by Kiss1) neurons in the arcuate nucleus coexpress neurokinin B (Tac3) and dynorphin (Pdyn) and are critical for regulating the GnRH/LH pulse. We therefore examined kisspeptin neurons by histochemistry and pulsatile LH release in rats aged 2-3 (Young)
 12-13 (YoungMiddle)
 19-22 (Late-Middle)
 and 24-26 (Old) months. Total LH concentrations
 sampled for 3 hours
 decreased in both sexes with aging. In females
 numbers of Tac3 and Pdyn neurons were significantly reduced in all aging rats
 and numbers of Kiss1 neurons were significantly reduced in Late-Middle and Old rats. In males
 numbers of all 3 neuron-types were significantly decreased in all aging rats. GnRH agonist induced LH release in all animals; however
 the increased LH concentration in all aging rats was less than that in Young rats. These results suggest that expression of each gene in kisspeptin neurons may be controlled individually during aging
 and that reduction of their expression or change in pituitary responsiveness may cause attenuated pulsatile LH secretion. (C) 2016 Elsevier Inc. All rights reserved.

NEUROBIOLOGY OF AGING

ELSEVIER SCIENCE INC

50

10.1016/j.neurobiolaging.2016.10.018

https://doi.org/10.1016/j.neurobiolaging.2016.10.018
https://www.ncbi.nlm.nih.gov/pubmed/27842268
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