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Updated: Jan 22, 2026

Dual Somatic Recordings from Gonadotropin-Releasing Hormone GnRH Neurons Identified by Green Fluorescent Protein GFP in Hypothalamic Slices
Published on: February 23, 2010
Reproductive neuroendocrinology of mammalian gonadotropin-inhibitory hormone
Takayoshi Ubuka1, Kazuyoshi Tsutsui1
1Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science Waseda University Shinjuku Japan.
Background:
Gonadotropin-inhibitory hormone (GnIH) was discovered in the Japanese quail brain in 2000 as a hypothalamic neuropeptide that suppresses luteinizing hormone release from cultured quail anterior pituitary.
Methods:
The authors investigated the existence of mammalian orthologous peptides to GnIH and their physiological functions in the following 19 years of research.
Main Findings:
Mammals have orthologous peptide to GnIH, often described RFamide-related peptide, expressed in the hypothalamus and gonads. Mammalian GnIH may also suppress gonadotropin synthesis and release by suppressing gonadotropin-releasing hormone (GnRH) synthesis and release in addition to directly suppressing gonadotropin synthesis and release from the pituitary. Mammalian GnIH may also suppress kisspeptin, a stimulator of GnRH, release. Mammalian GnIH is also expressed in the testis and ovary and suppresses gametogenesis and sex steroid production acting in an autocrine/paracrine manner. Thus, mammalian GnIH may act at all levels of the hypothalamic-pituitary-gonadal axis to suppress reproduction. GnIH may be involved in the regulation of puberty, estrous or menstrual cycle, seasonal reproduction, and stress responses.
Conclusion:
Studies suggest that mammalian GnIH is an important neuroendocrine suppressor of reproduction in mammals.
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