Yoshimura A, Saito S, Saito C T, Takahashi K, Tominaga M, Ohta T
Department of Veterinary Pharmacology, Tottori University, Tottori, Japan.
Division of Cell Signaling, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi, 444-8787, Japan.
Biochem Biophys Rep. 2022 Jul 21;31:101315. doi: 10.1016/j.bbrep.2022.101315. eCollection 2022 Sep.
Transient receptor potential vanilloid 1 (TRPV1) is mainly expressed in nociceptive primary sensory neurons and acts as a sensor for heat and capsaicin. The functional properties of TRPV1 have been reported to vary among species and, in some cases, the species difference in its thermal sensitivity is likely to be associated with thermal habitat conditions. To clarify the functional properties and physiological roles of TRPV1 in aquatic vertebrates, we examined the temperature and chemical sensitivities of TRPV1 in masu salmon (, Om) belonging to a family of salmonids that generally prefer cool environments. First, behavioral experiments were conducted using a video tracking system. Application of capsaicin, a TRPV1 agonist, induced locomotor activities in juvenile Om. Increasing the ambient temperature also elicited locomotor activity potentiated by capsaicin. RT-PCR revealed TRPV1 expression in gills as well as spinal cord. Next, electrophysiological analyses of OmTRPV1 were performed using a two-electrode voltage-clamp technique with a oocyte expression system. Heat stimulation evoked an inward current in heterologously expressed OmTRPV1. In addition, capsaicin produced current responses in OmTRPV1-expressing oocytes, but higher concentrations were needed for its activation compared to the mammalian orthologues. These results indicate that Om senses environmental stimuli (heat and capsaicin) through the activation of TRPV1, and this channel may play important roles in avoiding environments disadvantageous for survival in aquatic vertebrates.
瞬时受体电位香草酸亚型1（TRPV1）主要表达于伤害性初级感觉神经元，作为热和辣椒素的感受器。据报道，TRPV1的功能特性在不同物种间存在差异，在某些情况下，其热敏感性的物种差异可能与热栖息地条件有关。为阐明TRPV1在水生脊椎动物中的功能特性和生理作用，我们检测了属于鲑科的马苏大麻哈鱼（Oncorhynchus masou，Om）中TRPV1的温度和化学敏感性，该科鱼类通常偏好凉爽环境。首先，使用视频跟踪系统进行行为实验。应用TRPV1激动剂辣椒素可诱导幼年Om产生运动活动。提高环境温度也会引发由辣椒素增强的运动活动。逆转录聚合酶链反应（RT-PCR）显示TRPV1在鳃和脊髓中均有表达。接下来，使用双电极电压钳技术和爪蟾卵母细胞表达系统对OmTRPV1进行电生理分析。热刺激在异源表达的OmTRPV1中诱发内向电流。此外，辣椒素在表达OmTRPV1的卵母细胞中产生电流反应，但与哺乳动物同源物相比，其激活需要更高的浓度。这些结果表明，Om通过激活TRPV1感知环境刺激（热和辣椒素），并且该通道可能在水生脊椎动物避免不利于生存的环境中发挥重要作用。
