Tripiciano A, Filippini A, Giustiniani Q, Palombi F
Institute of Histology and General Embryology, La Sapienza University, Rome, Italy.
Biol Reprod. 1996 Jul;55(1):25-31. doi: 10.1095/biolreprod55.1.25.
Seminiferous tubule contractility is fundamental for sperm progression towards the rete testis; hence its regulation represents a key point in male fertility. Endothelin-1 (ET-1), a potent stimulator of smooth muscle contractility, has recently been shown to be produced in the testis, as well as to bind to specific receptors on myoid cells and thereby activate intracellular signaling. The present paper illustrates contraction of isolated myoid cells in response to ET-1 both in phase-contrast and scanning electron microscopy. Moreover, a simple method is described that allows visualization of a dramatic endothelin-induced rearrangement of myoid cell actin filaments in whole-mount preparations of seminiferous tubules. The response, which can be observed within seconds from stimulation, was paralleled by cell shape changes that were well apparent in scanning electron microscopy. The present report provides the first direct evidence that endothelin is an agonist of myoid cell contractility. Moreover, the experimental approach described could represent a promising tool for the screening of potential agonists of peritubular contractility and for the analysis of their mechanisms of action. In this regard, preliminary evidence is presented on myoid cell contractile response to [Arg8]-vasopressin.
生精小管的收缩性对于精子向睾丸网的推进至关重要；因此，对其调节是男性生育能力的关键所在。内皮素-1（ET-1）是平滑肌收缩性的强效刺激物，最近的研究表明它在睾丸中产生，并且能与肌样细胞上的特定受体结合，从而激活细胞内信号传导。本文利用相差显微镜和扫描电子显微镜展示了分离的肌样细胞对ET-1的收缩反应。此外，还描述了一种简单的方法，可在生精小管整装标本中观察到内皮素诱导的肌样细胞肌动蛋白丝的显著重排。刺激后数秒内即可观察到这种反应，同时细胞形状发生变化，这在扫描电子显微镜下清晰可见。本报告首次提供了直接证据，证明内皮素是肌样细胞收缩性的激动剂。此外，所描述的实验方法可能是筛选睾丸周肌收缩性潜在激动剂及其作用机制分析的有前景的工具。在这方面，还给出了肌样细胞对[精氨酸8]-加压素收缩反应的初步证据。
