Université de Caen Basse-Normandie, IBFA, Biologie des Mollusques marins et des Ecosystèmes Associés (BioMEA), 14032 Caen Cedex, France.
Peptides. 2012 Apr;34(2):303-10. doi: 10.1016/j.peptides.2012.01.017. Epub 2012 Jan 28.
Gonadotropin-releasing hormone (GnRH), a key neuropeptide regulating reproduction in vertebrates has now been characterized in a number of non-vertebrate species. Despite the demonstration of its ancestral origin, the structure and the function of this family of peptides remain poorly known in species as distant as lophotrochozoans. In this study, two GnRH-related peptides (Cg-GnRH-a and CgGnRH-G) were characterized by mass spectrometry from extracts of the visceral ganglia of the Pacific oyster Crassostrea gigas. These peptides showed a high degree of sequence identity with GnRHs of other mollusks and annelids and to a lesser extent with those of vertebrates or with AKH and corazonins of insects. Both the mature peptides and the transcript encoding the precursor protein were exclusively expressed in the visceral ganglia. Significant differences in transcriptional activity of Cg-GnRH encoding gene were recorded in the ganglia along the reproductive cycle and according to trophic conditions with a higher level in fed animals compared to starved animals. This suggests the involvement of Cg-GnRHs as synchronizers of nutritional status with energy requirements during reproduction in oyster. Evidence for a role of Cg-GnRHs as neuroregulators and as neuroendocrine factors in bivalve is discussed.
促性腺激素释放激素（GnRH）是一种调节脊椎动物生殖的关键神经肽，现已在许多非脊椎动物物种中得到鉴定。尽管已经证明了它的祖先起源，但在像担轮动物这样遥远的物种中，这种肽家族的结构和功能仍然知之甚少。在这项研究中，通过质谱法从太平洋牡蛎（Crassostrea gigas）内脏神经节的提取物中鉴定出两种与 GnRH 相关的肽（Cg-GnRH-a 和 CgGnRH-G）。这些肽与其他软体动物和环节动物的 GnRH 具有高度的序列同一性，与脊椎动物或昆虫的 AKH 和心激素的同一性较小。成熟肽和编码前体蛋白的转录本仅在内脏神经节中表达。在生殖周期中，以及根据营养条件，Cg-GnRH 编码基因的转录活性在神经节中存在显著差异，与饥饿动物相比，摄食动物中的水平更高。这表明 Cg-GnRHs 参与了牡蛎生殖过程中营养状况与能量需求的同步。讨论了 Cg-GnRHs 作为神经调节剂和贝类神经内分泌因子的作用证据。
