Centro Nacional de Investigación Disciplinaria en Parasitología Veterinaria, Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias INIFAP, Carr. Fed. Cuernavaca-Cuautla No. 8534, Jiutepec, Morelos, CP 62550, Mexico.
J Insect Physiol. 2012 May;58(5):628-33. doi: 10.1016/j.jinsphys.2012.01.006. Epub 2012 Feb 17.
The cattle tick Rhipicephalus microplus, is one of the most damaging livestock ectoparasites. Tropical tick infestation limits the introduction of high-yield bovine varieties because they do not have immunity to the diseases transmitted by these ectoparasites. This tick is usually controlled with chemical acaricides but their indiscriminate use has created resistant populations. The discovery of new molecules that can be used for tick control is urgent. Based on the knowledge that octopamine, a biogenic amine analog to epinephrine, is central to the regulation of oviposition in several studied arthropods and that an imbalance in octopamine release causes sterility in a Drosophila model. Tyramine, octopamine and epinastine and 83 adrenergic compounds classified by their effect in the vertebrate systems were screened for their ability to block oviposition in Rhipicephalus microplus. Of these molecules, we found that 10 alpha-agonists, 3 alpha-antagonists, 5 beta-adrenergic agonists, 7 beta-antagonists and Norepinephrine were able to inhibit oviposition in this tick at pharmacological concentrations. Surprisingly, tyramine appears to be more potent than octopamine. The probable physiological causes of this inhibition are discussed. Our results suggest that although there are alpha adrenergic-like receptors in the tick, they do not behave in a manner completely analogous to their vertebrate counterparts.
牛蜱 Rhipicephalus microplus 是最具破坏性的牲畜外寄生虫之一。热带蜱虫的侵袭限制了高产牛品种的引进，因为它们对这些外寄生虫传播的疾病没有免疫力。这种蜱虫通常用化学杀蜱剂控制，但它们的滥用以致产生了耐药种群。迫切需要发现可用于控制蜱虫的新分子。基于这样的认识，章鱼胺，一种与肾上腺素类似的生物胺，在几种研究过的节肢动物的产卵调节中起着核心作用，并且章鱼胺释放的不平衡会导致果蝇模型中的不育。章鱼胺、去甲肾上腺素和 83 种肾上腺素化合物按其在脊椎动物系统中的作用分类，筛选它们抑制 Rhipicephalus microplus 产卵的能力。在这些分子中，我们发现 10 种 alpha 激动剂、3 种 alpha 拮抗剂、5 种 beta 肾上腺素激动剂、7 种 beta 拮抗剂和去甲肾上腺素能够以药理浓度抑制这种蜱虫的产卵。令人惊讶的是，酪胺似乎比章鱼胺更有效。讨论了这种抑制的可能生理原因。我们的结果表明，尽管蜱虫中存在 alpha 肾上腺素样受体，但它们的行为并不完全类似于其脊椎动物对应物。
