Effect of galanin-like peptide on hypothalamic kisspeptin expression in female Zucker fatty rats

Akiko Sakata; Kinuyo Iwata; Kimihiko Nakao; Yuyu Kunimura; Shunji Suzuki; Hitoshi Ozawa; Hirotaka Ishii

doi:10.1016/j.neulet.2024.138081

Effect of galanin-like peptide on hypothalamic kisspeptin expression in female Zucker fatty rats

Neurosci Lett. 2024 Dec 12:846:138081. doi: 10.1016/j.neulet.2024.138081. Online ahead of print.

Authors

Akiko Sakata¹, Kinuyo Iwata², Kimihiko Nakao³, Yuyu Kunimura⁴, Shunji Suzuki³, Hitoshi Ozawa⁵, Hirotaka Ishii⁴

Affiliations

¹ Department of Reproductive Medicine, Perinatology and Gynecologic Oncology, Graduate School of Medicine, Nippon Medical School, Bunkyo-ku, Tokyo 113-8602, Japan; Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School, Bunkyo-ku, Tokyo 113-8602, Japan.
² Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School, Bunkyo-ku, Tokyo 113-8602, Japan. Electronic address: kiwata0309@nms.ac.jp.
³ Department of Reproductive Medicine, Perinatology and Gynecologic Oncology, Graduate School of Medicine, Nippon Medical School, Bunkyo-ku, Tokyo 113-8602, Japan.
⁴ Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School, Bunkyo-ku, Tokyo 113-8602, Japan.
⁵ Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School, Bunkyo-ku, Tokyo 113-8602, Japan; Department of Physical Therapy, Faculty of Health Sciences, Bukkyo University, Nakagyo-ku, Kyoto 604-8418, Japan.

PMID: 39672293
DOI: 10.1016/j.neulet.2024.138081

Abstract

Kisspeptin and galanin-like peptide (GALP) neurons in the hypothalamic arcuate nucleus (ARC) are involved in gonadotropin-releasing hormone (GnRH) neuron-mediated pulsatile luteinizing hormone (LH) secretion. Zucker fatty (ZF) rats display a leptin receptor gene abnormality and suppressed pulsatile LH secretion. ZF rats reportedly exhibit low hypothalamic GALP and kisspeptin expression, and GALP administration induces LH release in ZF rats. Therefore, we performed a histochemical analysis to determine whether GALP-induced LH release is mediated by kisspeptin neurons in ZF rats. All ZF rats were ovariectomized and subcutaneously implanted with an estradiol tube before the central injection of GALP or vehicle. GALP administration increased the plasma LH concentration. However, no significant difference was observed in the number of Kiss1 cells and the proportion of Fos-positive Kiss1 cells. The number of c-Fos-positive GnRH neurons significantly increased after GALP administration. Our results suggest that hypothalamic GALP neurons promote LH release by activating GnRH neurons without the activation of kisspeptin neurons in the ARC.

Keywords: Arcuate nucleus; GnRH; Infertility; Kiss1; Luteinizing hormone; Obesity.