Weisel-Eichler A, Libersat F
Department of Life Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer Sheva, Israel.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2002 May;188(4):315-24. doi: 10.1007/s00359-002-0305-y. Epub 2002 Apr 11.
The venom of the parasitoid wasp Ampulex compressa induces long-lasting hypokinesia in the cockroach prey. Previous work indicates that the venom acts in the subesophageal ganglion to indirectly affect modulation of thoracic circuits for locomotion. However, the target of the venom in the subesophageal ganglion, and the mechanism by which the venom achieves its effects are as yet unknown. While the stung cockroaches appear generally lethargic, not all behaviors were affected, indicating that the venom targets specific motor systems and not behavior in general. Stung cockroaches were observed "freezing" in abnormal positions. Reserpine, which depletes monoamines, mimics the behavioral effects of the venom. We treated cockroaches with antagonists to dopamine and octopamine receptors, and found that the dopamine system is required for normal escape response. Dopamine injection induces prolonged grooming in normal cockroaches, but not in stung, suggesting that the venom is affecting dopamine receptors, or targets downstream of these receptors, in the subesophageal ganglion. This dopamine blocking effect fades slowly over the course of several weeks, similar to the time course of recovery from hypokinesia. The similarity in the time courses suggests that the mechanism underlying the hypokinesia may be the block of the dopamine receptors.
寄生黄蜂扁头泥蜂的毒液会使蟑螂猎物产生持久的运动减退。先前的研究表明，毒液作用于咽下神经节，间接影响调节胸部运动回路。然而，毒液在咽下神经节中的作用靶点以及毒液产生作用的机制尚不清楚。虽然被蜇的蟑螂通常显得无精打采，但并非所有行为都会受到影响，这表明毒液针对的是特定的运动系统，而非一般行为。观察到被蜇的蟑螂会在异常位置“僵住”。利血平可消耗单胺类物质，它能模拟毒液的行为效应。我们用多巴胺和章鱼胺受体拮抗剂处理蟑螂，发现多巴胺系统是正常逃避反应所必需的。向正常蟑螂注射多巴胺会诱导其长时间梳理行为，但对被蜇蟑螂则无此作用，这表明毒液正在影响咽下神经节中的多巴胺受体，或作用于这些受体的下游靶点。这种多巴胺阻断效应在数周内会缓慢消退，类似于运动减退恢复的时间进程。时间进程上的相似性表明，运动减退的潜在机制可能是多巴胺受体的阻断。
