血管加壓素在斑馬魚離子調控中扮演的角色

Abstract

過去研究中有關血管加壓素(AVP)的主要角色是參與調控哺乳類腎臟離子及水分平衡的功能，而AVP的同源基因AVT在魚類生理中調控滲透壓平衡的角色也常被提及，但對於其調節的機制卻所知有限。本實驗目的為利用分子生物學、生化及生理學的方法研究AVT在斑馬魚離子運輸及滲透壓平衡中所扮演的角色及調控機制。實驗中利用RT-PCR的方式檢測AVT於不同胚胎時期及成魚各組織間的表現，並進一步觀察胚胎於低張環境中AVT基因的表現情形。結果顯示AVT於胚胎發育極早期即有表現及廣泛表現於成魚不同組織中並在低張環境中表現增加。此外，以專一的反義核酸 (morpholini oligos) 抑制AVT短肽的合成後，鈉離子及氯離子在胚胎中的含量顯著性地下降，離子運輸蛋白基因表現及富鈉鉀幫浦細胞(Na+-K+-ATPase-riched cell)、富氫幫浦細胞(H+-ATPase-riched cell)的細胞密度皆顯著下降，而與離子細胞分化相關的轉錄因子的基因表現及表皮幹細胞密度等亦顯著地下降。綜合以上所述，AVT參與調控斑馬魚胚胎時期的離子平衡並與離子細胞之分化與增生的調控機制上扮演重要的角色。

Arginine vasopressin (AVP) has been found to be involved in ionoregulation and water metabolisms in kidney of mammals. Arginine vasotocin, as the homolog of AVP, were also mentioned frequently in fish physiology but only little was known about the regulatory mechanisms. The purpose of the present study is to explore the role of AVT in ion regulatory mechanisms in zebrafish by using molecular physiological approaches. The mRNA expression were detected by RT-PCR and results showed that AVT gene expressed in very early stage and expressed extensively in different tissues in addition to brain. AVT gene expression was also found to increase in hypoosmotic environment by using qRT-PCR. Besides, the ion content of Cl- and Na+, expression of several ionocyte-related genes, essential transcription factor for ionocyte differentiation, and epidermal stem cell were decreased by knockdown of AVT gene. Taken all together, AVT plays important roles in ion regulation of zebrafish embryo and participates in both cell proliferation and differentiation of ionocyte.