Melzig J, Buchner S, Wiebel F, Wolf R, Burg M, Pak W L, Buchner E
Theodor Hoveri Institut für Biowissenschaften, Würzburg, Germany.
J Comp Physiol A. 1996 Dec;179(6):763-73. doi: 10.1007/BF00207355.
The role of histamine as a fast neurotransmitter of imaginal insect photoreceptors is firmly established. In adult Drosophila, histamine is also found in mechanosensory receptors of cuticular hair sensilla and in a small number of nonreceptor neurons in head and body ganglia. Here we investigate the function of histamine by immunohistochemical and behavioral analysis of mutants deficient in the hdc gene that codes for histidine decarboxylase. The allele hdcJK910 appears to be a null mutation, as histamine immunoreactivity is almost entirely eliminated. Homozygous flies are blind in various behavioral paradigms. Mutant larvae, on the other hand, show normal photokinetic responses. Thus, adult Drosophila photoreceptors most likely utilize only a single substance, histamine, as a neurotransmitter, whereas larval photoreceptors apparently employ a different transmitter. With the alleles hdcP211, hdcP217, and hdcP218, variable amounts of histamine are found in photoreceptors and mechanoreceptors, but no histamine could be detected in any of the nonreceptor neurons. These mutants show various degrees of visual and mechanosensory impairment, as determined by quantitative behavioral assays. We conclude that histamine is required for normal function of cuticular hair sensilla and for efficient grooming of the body surface. Thus, in Drosophila, histamine represents a major functional neurotransmitter for mechanosensory receptors.
组胺作为昆虫成虫视觉感受器的快速神经递质，其作用已得到确凿证实。在成年果蝇中，组胺也存在于表皮毛感觉器的机械感受器以及头部和身体神经节中的少数非感受器神经元中。在这里，我们通过对编码组氨酸脱羧酶的hdc基因突变体进行免疫组织化学和行为分析，来研究组胺的功能。等位基因hdcJK910似乎是一个无效突变，因为组胺免疫反应性几乎完全消失。纯合子果蝇在各种行为范式中均失明。另一方面，突变幼虫表现出正常的光动力学反应。因此，成年果蝇的光感受器很可能仅利用单一物质组胺作为神经递质，而幼虫的光感受器显然使用的是不同的递质。对于等位基因hdcP211、hdcP217和hdcP218，在光感受器和机械感受器中发现了不同量的组胺，但在任何非感受器神经元中均未检测到组胺。通过定量行为分析确定，这些突变体表现出不同程度的视觉和机械感觉障碍。我们得出结论，组胺是表皮毛感觉器正常功能以及体表有效梳理所必需的。因此，在果蝇中，组胺是机械感受器的主要功能性神经递质。
