Rocha Thalita, Leonardo Marta Beatriz, De Souza Bibiana Monson, Palma Mario Sérgio, Da Cruz-Höfling Maria Alice
Department of Histology and Embryology, Institute of Biology, UNICAMP, Campinas, SP 13083-970, Brazil.
Microsc Res Tech. 2008 Mar;71(3):220-9. doi: 10.1002/jemt.20542.
Animal venoms have been valuable sources for development of new drugs and important tools to understand cellular functioning in health and disease. The venom of Polybia paulista, a neotropical social wasp belonging to the subfamily Polistinae, has been sampled by headspace solid phase microextraction and analyzed by gas chromatography-mass spectrometry. Recent study has shown that mastoparan, a major basic peptide isolated from the venom, reproduces the myotoxic effect of the whole venom. In this study, Polybia-MPII mastoparan was synthesized and studies using transmission electron microscopy were carried out in mice tibial anterior muscle to identify the subcellular targets of its myotoxic action. The effects were followed at 3 and 24 h, 3, 7, and 21 days after mastoparan (0.25 mug/muL) intramuscular injection. The peptide caused disruption of the sarcolemma and collapse of myofibril arrangement in myofibers. As a consequence, fibers presented heteromorphic amorphous masses of agglutinated myofilaments very often intermingled with denuded sarcoplasmic areas sometimes only surrounded by a persistent basal lamina. To a lesser extent, a number of fibers apparently did not present sarcolemma rupture but instead appeared with multiple small vacuoles. The results showed that sarcolemma, sarcoplasmic reticulum (SR), and mitochondria were the main targets for mastoparan. In addition, a number of fibers showed apoptotic-like nuclei suggesting that the peptide causes death both by necrosis and apoptosis. This study presents a hitherto unexplored view of the effects of mastoparan in skeletal muscle and contributes to discuss how the known pharmacology of the peptide is reflected in the sarcolemma, SR, mitochondria, and nucleus of muscle fibers, apparently its subcellular targets.
动物毒液一直是新药开发的宝贵来源，也是了解健康和疾病状态下细胞功能的重要工具。多刺蚁属新热带群居黄蜂，属于蚁亚科，其毒液已通过顶空固相微萃取法采集，并通过气相色谱 - 质谱联用仪进行分析。最近的研究表明，从毒液中分离出的主要碱性肽马斯托帕兰能重现全毒液的肌毒性作用。在本研究中，合成了多刺蚁 - MPII马斯托帕兰，并在小鼠胫前肌中利用透射电子显微镜进行研究，以确定其肌毒性作用的亚细胞靶点。在肌肉注射马斯托帕兰（0.25微克/微升）后的3小时和24小时、3天、7天和21天观察其效果。该肽导致肌纤维的肌膜破坏和肌原纤维排列紊乱。结果，肌纤维出现异形的无定形凝集肌丝团块，常常与裸露的肌浆区域交织在一起，有时仅被持续存在的基膜包围。在较小程度上，一些肌纤维显然没有出现肌膜破裂，而是出现多个小液泡。结果表明，肌膜、肌浆网（SR）和线粒体是马斯托帕兰的主要靶点。此外，一些肌纤维显示出类似凋亡的细胞核，表明该肽通过坏死和凋亡导致细胞死亡。本研究提出了马斯托帕兰对骨骼肌作用的一个迄今未被探索的观点，并有助于讨论该肽已知的药理学特性如何在肌纤维的肌膜、SR、线粒体和细胞核（显然是其亚细胞靶点）中体现。
