Functional analysis of novel G-coupled receptor candidate for L-DOPA and structural determination of its ligands

我们提出l -3,4-二羟基苯丙氨酸（DOPA）作为压力受体传入神经元的神经递质候选者，其终点位于孤束核（NTS）。我们通过对非洲爪蟾左卵细胞的表达筛选，分离出秀丽隐杆线虫C06H5.7基因作为DOPA的候选受体。对C06H5.7的电生理分析表明，C06H5.7对多巴的非胺代谢物有反应，但对自身无反应。在此之前，我们报道了3,4-二羟基苯甲醛（DHBALD）作为C06H5.7的活性配体之一。一种有气味的苯甲醛，在电生理激活C06H5.7的化学结构上与DHBALD相似。虽然AWC感觉神经元所感知的低浓度苯甲醛是一种趋化剂，但目前尚未检测到C06H5.7在AWC中的表达。C06H5.7的零突变候选体nj66对苯甲醛的吸引没有缺陷。另一方面，高浓度苯甲醛在灰灰感觉神经元中是一种化学驱避剂，但其受体尚未确定。为了验证C06H5.7是否参与了厌恶机制，我们对nj66进行了厌恶实验，并检测了C06H5.7在ASH中的表达。然而，当将这些配体微注射到孤立束核时，这些配体对麻醉大鼠的血压和心率没有影响。

We proposed L-3,4-dihydroxyphenylalanine (DOPA) as a neurotransmitter candidate of baroreceptor afferent neurons terminating in the nucleus tractus solitarii (NTS). We have isolated C.elegans C06H5.7 gene as a receptor candidate for DOPA through expression screening using Xenopus laevisoocytes. Electrophysiological analyses of C06H5.7 showed that C06H5.7 responded to non-amine metabolites of DOPA, but did not to itself. Previously, we have reported that 3,4-dihydroxybenzaldehyde (DHBALD) acts as one of active ligands for C06H5.7. An odorant benzaldehyde that is similar to DHBALD in the chemical structure electrophysiologically activated C06H5.7. Although benzaldehyde at low concentrations sensed by AWC sensory neurons is a chemoattractants in C.eleagans, expression of C06H5.7 have not yet been detected in AWC. A null mutant candidate for C06H5.7, nj66,was not defective in the attraction by benzaldehyde. On the other hand, benzaldehyde at high concentrations sensed by ASH sensory neurons is a chemorepellent in C.eleagans, but its receptor has not yet been identified. To test the possibility that C06H5.7 is involved in the aversive mechanisms, we are performing the aversion assay of nj66 and detecting the expression of C06H5.7 in the ASH. However, these ligands produced no effects on blood pressure and hear rates of anesthetized rats, when these were microinjected into the nucleus tractus solitarii.