Sells P G, Ioannou P, Theakston R D
Alistair Reid Venom Research Unit, Liverpool School of Tropical Medicine, UK.
Toxicon. 1998 Jul;36(7):985-91. doi: 10.1016/s0041-0101(98)00004-x.
The accurate measurement of venom lethality is the basis of clinical treatment of snakebite and of much venom-related research. Lethality tests are necessarily carried out in animal models and the results extrapolated to man. While we may be confounded by the obvious limitations of this approach, we can improve the situation by using a non-sentient living system, such as the very early developmental stage of the chick embryo, as an alternative to lethality testing in mammals. The continuing need for lethality testing of venoms and their isolated components, which underpins the development and assessment of antivenoms, currently accounts for thousands of mice annually; this is becoming increasingly unacceptable, first because of the amount of suffering caused and second, because of the high cost incurred. We describe here the use of 4 6 d old chick embryos as a system for estimating venom lethality. The shell-less yolk sac membrane offers a vascular system which develops before intact nervous reflex arcs are functional and therefore the embryo is incapable of experiencing pain. Venom is applied to the membrane on a filter paper disc and its effects on vascular and cardiac function are easily observed throughout the 6 h experiment. Eight venoms tested on eggs and by conventional LD50 assays in mice were compared. A highly significant correlation was obtained suggesting that this simple and inexpensive test would be a far more acceptable alternative for non-neurotoxic venoms.
准确测量毒液致死性是蛇咬伤临床治疗及许多与毒液相关研究的基础。致死性测试必须在动物模型中进行，并将结果外推至人类。尽管我们可能会因这种方法的明显局限性而感到困惑，但我们可以通过使用一种无感知的活体系统，比如鸡胚的极早期发育阶段，来替代在哺乳动物身上进行的致死性测试，从而改善这种情况。对毒液及其分离成分进行致死性测试的持续需求是抗蛇毒血清研发和评估的基础，目前每年需要使用数千只小鼠；这正变得越来越不可接受，一方面是因为造成的痛苦，另一方面是因为成本高昂。我们在此描述使用4至6日龄鸡胚作为评估毒液致死性的系统。无壳卵黄囊膜提供了一个在完整神经反射弧发挥功能之前就已发育的血管系统，因此胚胎无法感知疼痛。将毒液涂在滤纸片上，敷于膜上，在整个6小时的实验过程中，其对血管和心脏功能的影响很容易观察到。对在鸡蛋上测试的8种毒液以及通过传统小鼠半数致死量（LD50）测定法测试的结果进行了比较。结果获得了高度显著的相关性，这表明这种简单且廉价的测试对于非神经毒性毒液而言是一种更可接受的替代方法。
