Osborne N N, Ghazi H
Nuffield Laboratory of Ophthalmology, University of Oxford, U.K.
Vision Res. 1989;29(7):757-64. doi: 10.1016/0042-6989(89)90088-6.
Substance P and eledoisin stimulate the accumulation of inositol phosphates in a dose-dependent manner in retinal and superior colliculus slices of the rabbit. The EC50 values for substance P and eledoisin in both tissues were of the same order (1.5-4.9 microM), suggesting that the receptors in the two tissues were alike with characteristics of the SP-P subtype rather than the SP-E subtype. These data suggest that the SP-immunoreactive material in the retinal ganglion and amacrine cells is identical. The effectiveness for a number of tachykinin substances at 10(-5) M for stimulating inositol phosphates accumulation was as follows: Substance P greater than eledoisin greater than neurokinin A greater than neurokinin B greater than substance P (octapeptide) greater than substance P (pentapeptide). Spantide [(D-Arg1, D-Try7.9, Leu11) substance P] and (D-Pro2, D-Try7.9) substance P did not stimulate inositol phospholipid hydrolysis. However, spantide, at a concentration of 10(-6) M, was an antagonist of the effect produced by substance P, but had no action on the effect produced by neurokinin A or neurokinin B. Substance P and other tachykinins were also effective in stimulating inositol phosphates accumulation in 3-5-day-old rabbit retinal cultures but did not elicit a response in the older (25-30-day-old) cultures which lacked neurones but contained Müller cells. Furthermore, substance P was only active in the younger cultures in stimulating an increase in internal calcium levels. It is therefore concluded that retinal tachykinin receptors linked to phosphoinositide turnover and calcium mobilisation are associated exclusively with neurones and not with Müller cells.
P物质和eledoisin以剂量依赖的方式刺激兔视网膜和上丘切片中肌醇磷酸的积累。P物质和eledoisin在两种组织中的EC50值处于同一数量级（1.5 - 4.9 microM），这表明两种组织中的受体相似，具有SP - P亚型而非SP - E亚型的特征。这些数据表明视网膜神经节细胞和无长突细胞中的P物质免疫反应性物质是相同的。多种速激肽物质在10(-5) M浓度下刺激肌醇磷酸积累的有效性如下：P物质＞eledoisin＞神经激肽A＞神经激肽B＞P物质（八肽）＞P物质（五肽）。Spantide [（D - Arg1，D - Try7.9，Leu11）P物质]和（D - Pro2，D - Try7.9）P物质不刺激肌醇磷脂水解。然而，浓度为10(-6) M的spantide是P物质产生效应的拮抗剂，但对神经激肽A或神经激肽B产生的效应无作用。P物质和其他速激肽在3 - 5日龄兔视网膜培养物中刺激肌醇磷酸积累也有效，但在缺乏神经元但含有米勒细胞的较老（25 - 30日龄）培养物中未引发反应。此外，P物质仅在较年轻的培养物中对刺激细胞内钙水平升高有活性。因此得出结论，与磷酸肌醇代谢和钙动员相关的视网膜速激肽受体仅与神经元相关，而与米勒细胞无关。
