Department of Biology, Memorial University of Newfoundland, St. John's, Newfoundland, Canada A1B-3X9.
Gen Comp Endocrinol. 2013 Apr 1;184:9-21. doi: 10.1016/j.ygcen.2012.12.010. Epub 2013 Jan 5.
Gonadotrophin-releasing hormone (GnRH) is primarily related to reproductive processes in vertebrates. However other physiological roles, including functions in food intake regulation and energy status, have been demonstrated for GnRH in animals. The ten amino acid active peptide is relatively conserved throughout chordates, more specifically in fish species. Teleosts generally have at least two variants of GnRH present in their genomes. GnRH2 (commonly termed chicken-GnRH) is common to all fish, whereas other prevalent forms include GnRH1 and/or GnRH3 (also known as salmon-GnRH). The mRNAs of all three forms were identified in winter flounder (Pseudopleuronectes americanus). Winter flounder GnRH1 appears to be ubiquitously and strongly expressed throughout the brain. GnRH2 mRNA is highly expressed in the optic tectum/thalamus. Finally, GnRH3 mRNA is expressed throughout the brain, but not in the pituitary, with apparent highest expression in the telencephalon/preoptic area. Flounder GnRH1 mRNA is found in most peripheral tissues examined, including the foregut, midgut and gonads. GnRH2 mRNA appears to be expressed throughout the periphery, with apparent highest transcript expression in male gonads. Finally, winter flounder GnRH3 transcript is found at low levels in the skin, heart, and gonads. The effect of fasting on the expression of each of the three isoforms was assessed. Fasting reduces GnRH2 and GnRH3 mRNA expression in the optic tectum/thalamus and hypothalamus, and telencephalon/preoptic area, respectively, compared with fed fish. GnRH1 mRNA expression does not appear to be altered by feeding status. GnRH mRNAs do not seem to regulate food intake peripherally through the gut based on our preliminary findings. Our preliminary results suggest that the GnRH system could play a central role in food intake regulation of winter flounder.
促性腺激素释放激素（GnRH）主要与脊椎动物的生殖过程有关。然而，其他生理作用，包括在食物摄入调节和能量状态中的作用，在动物中的 GnRH 中已经得到证实。这种十肽的活性肽在脊索动物中相对保守，在鱼类中更为明显。硬骨鱼类通常在其基因组中至少存在两种 GnRH 变体。GnRH2（通常称为鸡-GnRH）存在于所有鱼类中，而其他常见形式包括 GnRH1 和/或 GnRH3（也称为鲑鱼-GnRH）。所有三种形式的 mRNA 都在美洲拟鲽（Pseudopleuronectes americanus）中被鉴定出来。美洲拟鲽 GnRH1 似乎在整个脑中广泛且强烈表达。GnRH2 mRNA 在视顶盖/丘脑高度表达。最后，GnRH3 mRNA 在整个脑中表达，但不在垂体中，在端脑/视前区表达最高。在检查的大多数外周组织中都发现了拟鲽 GnRH1 mRNA，包括前肠、中肠和性腺。GnRH2 mRNA 似乎在整个外周表达，在雄性性腺中具有最高的转录表达。最后，在皮肤、心脏和性腺中发现低水平的美洲拟鲽 GnRH3 转录本。评估了禁食对三种同工型表达的影响。与摄食鱼相比，禁食减少了视顶盖/丘脑和下丘脑、端脑/视前区中 GnRH2 和 GnRH3 mRNA 的表达。GnRH1 mRNA 表达似乎不受摄食状态的影响。根据我们的初步发现，GnRH 似乎不会通过肠道在外周调节食物摄入。我们的初步结果表明，GnRH 系统可能在美洲拟鲽的食物摄入调节中发挥中心作用。
