Wafford K A, Lummis S C, Sattelle D B
AFRC Unit of Insect Neurophysiology and Pharmacology, University of Cambridge, UK.
Proc R Soc Lond B Biol Sci. 1989 Jun 22;237(1286):53-61. doi: 10.1098/rspb.1989.0036.
The effects of a cyclodiene (endrin) and a cyclohexane (lindane) insecticide have been tested on gamma-aminobutyric acid (GABA) receptors in the central nervous system of the cockroach (Periplaneta americana), by using electrophysiological methods and an in vitro functional receptor assay. In electrophysiological experiments on an identified motor neuron (Df), endrin blocked the GABA response with a 50% inhibition concentration of 5.0 x 10(-7) M in a non-competitive manner. The actions of endrin were irreversible under the experimental conditions adopted. Increasing the intracellular chloride concentration reduced the effectiveness of endrin, whereas a change in the potassium concentration failed to influence the block by endrin of GABA responses. Lindane exhibited similar actions to endrin on insect GABA receptors, but was approximately an order of magnitude less effective. In a microsac preparation from cockroach nerve cords, endrin, at a concentration of 1.0 x 10(-5) M, completely blocked GABA-stimulated 36Cl- uptake, whereas the same concentration of lindane was less potent, only blocking about 40% of uptake under similar conditions. Neither insecticide had any effect on L-glutamate-activated chloride channels. The results demonstrate that endrin and lindane block functional insect neuronal GABA receptors.
通过使用电生理方法和体外功能性受体测定法，已对环二烯（异狄氏剂）和环己烷（林丹）杀虫剂对蟑螂（美洲大蠊）中枢神经系统中γ-氨基丁酸（GABA）受体的影响进行了测试。在对一个已识别的运动神经元（Df）进行的电生理实验中，异狄氏剂以非竞争性方式阻断GABA反应，其50%抑制浓度为5.0×10⁻⁷M。在所采用的实验条件下，异狄氏剂的作用是不可逆的。增加细胞内氯离子浓度会降低异狄氏剂的有效性，而改变钾离子浓度则未能影响异狄氏剂对GABA反应的阻断作用。林丹在昆虫GABA受体上表现出与异狄氏剂相似的作用，但效力约低一个数量级。在蟑螂神经索的微囊制剂中，浓度为1.0×10⁻⁵M的异狄氏剂完全阻断了GABA刺激的³⁶Cl⁻摄取，而相同浓度的林丹效力较低，在类似条件下仅阻断约40%的摄取。两种杀虫剂对L-谷氨酸激活的氯离子通道均无任何影响。结果表明，异狄氏剂和林丹可阻断功能性昆虫神经元GABA受体。
