Identification of neurohypophysial hormones and the role of VT in the parturition of pregnant seahorses (Hippocampus erectus).
Identification of neurohypophysial hormones and the role of VT in the parturition of pregnant seahorses (Hippocampus erectus).
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DOI：
10.3389/fendo.2022.923234
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发表时间：
2022
影响因子：
5.2
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中科院分区：
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神经垂体激素调节硬骨鱼的生殖行为；然而，它们在雄性怀孕的卵胎生鱼类(合体)的怀孕和分娩中的作用仍有待证实。本研究克隆并鉴定了直立海马精氨酸催产素(VT)和异催产素(IT)的互补DNA序列。我们观察到，在硬骨鱼中，海马VT和IT的成熟核心肽是保守的。在系统发育树中，海马VT和IT与硬骨鱼VT和IT独立聚为一类。VT和IT的组织分布模式相似，均在脑、鳃和性腺中高表达。有趣的是，它们在孵化囊中也有一定程度的表达。原位杂交显示脑内VT和IT信使RNA(MRNA)信号主要位于下丘脑视前区。给怀孕的海马注射VT核心肽会导致早产，刺激促性腺激素的释放，增加血清雌激素水平，减少催乳素的分泌。此外，VT注射还上调了孵化囊膜雌激素受体的mRNA表达。总而言之，神经垂体激素通过调节下丘脑-垂体-性腺轴的雌激素合成来促进早产。
Neurohypophysial hormones regulate the reproductive behavior of teleosts; however, their role in the gestation and parturition of ovoviviparous fishes with male pregnancy (syngnathids) remains to be demonstrated. In the present study, the complementary DNA (cDNA) sequences of arginine vasotocin (VT) and isotocin (IT) from the lined seahorse (Hippocampus erectus) were cloned and identified. We observed that the mature core peptides of seahorse VT and IT were conserved among teleosts. In the phylogenic tree, seahorse VT and IT were clustered independently with teleost VT and IT. The tissue distribution patterns of VT and IT were similar, and both were highly expressed in the brain, gills, and gonads. Interestingly, they were also expressed to some extent in the brood pouch. In situ hybridization revealed that VT and IT messenger RNA (mRNA) signals in the brain were mainly located in the preoptic area region of the hypothalamus. Intraperitoneal administration of the VT core peptide to pregnant seahorses induced premature parturition, stimulated gonadotropin release, increased serum estrogen levels, and decreased prolactin secretion. Moreover, VT injection upregulated the mRNA expression of the membrane estrogen receptor in the brood pouch. In summary, neurohypophysial hormones promote premature parturition by regulating estrogen synthesis through the hypothalamus–pituitary–gonad axis.