Canesi Laura, Borghi Cristina, Fabbri Rita, Ciacci Caterina, Lorusso Lucia Cecilia, Gallo Gabriella, Vergani Laura
Dipartimento di Biologia, Università di Genova, Corso Europa 26, 16132 Genova, Italy.
Gen Comp Endocrinol. 2007 Aug-Sep;153(1-3):40-6. doi: 10.1016/j.ygcen.2007.02.005. Epub 2007 Feb 12.
In bivalve molluscs the digestive gland (hepatopancreas) plays a central role in metabolism. In this work, the effects of 17beta-estradiol (E(2)) on digestive gland were evaluated in Mytilus galloprovincialis. Mussels were injected into the adductor muscle sinus with different amounts of the hormone (5, 25 and 100pmol) and tissues were sampled 24h post-injection. Functional parameters (lysosomal membrane stability-LMS, lysosomal accumulation of neutral lipids-NL and of lipofuscin-LF), as well as the activity of the key glycolytic enzymes PFK (phosphofructokinase) and PK (pyruvate kinase), and of the antioxidant enzyme catalase were evaluated. Selected genes, whose expression can be modulated by estrogens in mammalian systems and whose sequences have been identified in Mytilus, were investigated as possible targets for the action of E(2). E(2) induced a concentration-dependent decrease in LMS; such an effect was accompanied by an increase in NL accumulation, whereas the level of lipofuscin showed a slight, although not significant decrease. E(2) exposure also led to a significant increase in the activity of PFK and catalase but not of PK. Moreover, E(2) induced significant changes in the pattern of gene expression at the lower concentrations tested (5 and 25pmol) as evaluated by quantitative RT-PCR. In particular, increased transcription of catalase, as well as of the metallothionein 20 (MT20) isoform were observed; on the other hand, a decreased transcription of the p53 gene was detected. The results demonstrate that in Mytilus the digestive gland represents a target for the action of E(2), and that the hormone can modulate the lysosomal function, as well as lipid and glucose metabolism. Moreover, these data suggest that E(2) may also alter oxidative stress conditions in this tissue, as indicated by the increased transcription of genes (metallothionein and catalase) that play a role in antioxidant defences. Overall, the results indicate that E(2) can modulate both functional parameters and gene expression in mussel hepatopancreas and underline the importance of investigating also non-reproductive effects of estrogenic compounds in bivalve molluscs.
在双壳贝类软体动物中，消化腺（肝胰腺）在新陈代谢中起着核心作用。在这项研究中，评估了17β-雌二醇（E₂）对地中海贻贝消化腺的影响。将不同剂量的激素（5、25和100皮摩尔）注射到贻贝的闭壳肌窦中，并在注射后24小时采集组织样本。评估了功能参数（溶酶体膜稳定性-LMS、中性脂质-NL和脂褐素-LF的溶酶体积聚），以及关键糖酵解酶磷酸果糖激酶（PFK）和丙酮酸激酶（PK）的活性，以及抗氧化酶过氧化氢酶的活性。研究了一些选定的基因，其表达在哺乳动物系统中可被雌激素调节，且其序列已在地中海贻贝中鉴定出来，作为E₂作用的可能靶点。E₂导致LMS呈浓度依赖性下降；这种效应伴随着NL积累的增加，而脂褐素水平虽略有下降但不显著。暴露于E₂还导致PFK和过氧化氢酶的活性显著增加，但PK的活性未增加。此外，通过定量RT-PCR评估，在较低测试浓度（5和25皮摩尔）下，E₂诱导了基因表达模式的显著变化。特别是，观察到过氧化氢酶以及金属硫蛋白20（MT20）亚型的转录增加；另一方面，检测到p53基因的转录减少。结果表明，在地中海贻贝中，消化腺是E₂作用的靶点，该激素可调节溶酶体功能以及脂质和葡萄糖代谢。此外，这些数据表明E₂也可能改变该组织中的氧化应激条件，这由在抗氧化防御中起作用的基因（金属硫蛋白和过氧化氢酶）转录增加所表明。总体而言，结果表明E₂可调节贻贝肝胰腺中的功能参数和基因表达，并强调了研究双壳贝类中雌激素化合物非生殖效应的重要性。
