Gonadotrophin‐Inhibitory Hormone: A Multifunctional Neuropeptide
Tóm tắt
Gonadotrophin‐inhibitory hormone (GnIH) was discovered 8 years ago in birds. Its identification raised the possibility that gonadotrophin‐releasing hormone (GnRH) is not the sole hypothalamic neuropeptide that directly influences pituitary gonadotrophin release. Initial studies on GnIH focused on the avian anterior pituitary as comprising the only physiological target of GnIH. There are now several lines of evidence indicating that GnIH directly inhibits pituitary gonadotrophin synthesis and release in birds and mammals. Histological studies on projections from hypothalamic GnIH neurones subsequently implied direct actions of GnIH within the brain and in the periphery. In addition to actions on the pars distalis via the median eminence, GnIH axons and terminals are present in multiple brain areas in birds, and the GnIH receptor is expressed on GnRH‐I and ‐II neurones. Furthermore, we have demonstrated the presence of GnIH and its receptor in avian and mammalian gonads. Thus, GnIH can act directly at multiple levels: within the brain, on the pituitary and in the gonads. In sum, our data indicate that GnIH and its related peptides are important modulators of reproductive function at the level of the GnRH neurone, the gonadotroph and the gonads. Here, we provide an overview of the known levels of GnIH action in birds and mammals. In addition, environmental and physiological factors that are involved in GnIH regulation are reviewed.
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Tài liệu tham khảo
UbukaT BinnsM CadiganPA OsugiT ChowdhuryVS TsutsuiK BentleyGE.Identification of gonadotropin‐inhibitory hormone in human brain. Abstract 658.17 presented at the 36th Annual Meeting for the Society for Neuroscience Atlanta GA:Society for Neuroscience Washington DC 2006
Ubuka T, 2008, Taeniopygia guttata gonadotropin‐releasing hormone precursor mRNA, complete cds
ZhaoS BentleyGE TsutsuiK KriegsfeldLJ.Local regulation of spermatogenesis by gonadotropin‐inhibitory hormone. Abstract 831.9 presented at the 37th Annual Meeting for the Society for Neuroscience San Diego CA:Society for Neuroscience Washington DC 2007.
McGuireNL UbukaT KangasK BentleyGE.A novel neuropeptide system within primate gonads: RFRP and RFRPR in rhesus macaque (Macaca mulatta) testis and ovary.2009; unpublished data. submitted.
KirbyED UbukaT KauferD BentleyGE.Acute immobilization stress increases putative gonadotropin inhibitory hormone expression in the rat hypothalamus. Abstract 831.7 presented at the 37th Annual Meeting for the Society for Neuroscience San Diego CA:Society for Neuroscience Washington DC 2007.