Summers Torrie, Holec Sara, Burrell Brian D
Center for Brain and Behavior Research, Division of Basic Biomedical Sciences, Sanford, School of Medicine, University of South Dakota, Vermillion, SD 57069, USA.
Center for Brain and Behavior Research, Division of Basic Biomedical Sciences, Sanford, School of Medicine, University of South Dakota, Vermillion, SD 57069, USA
J Exp Biol. 2014 Dec 1;217(Pt 23):4167-73. doi: 10.1242/jeb.110049. Epub 2014 Oct 16.
Transient receptor potential vanilloid (TRPV) channels are found throughout the animal kingdom, where they play an important role in sensory transduction. In this study, we combined physiological studies with in vivo behavioral experiments to examine the presence of a putative TRPV-like receptor in the medicinal leech, building upon earlier studies in this lophotrochozoan invertebrate. The leech polymodal nociceptive neuron was activated by both peripheral and central application of the TRPV1-activator capsaicin in a concentration-dependent manner, with 100 μmol l(-1) being the lowest effective concentration. Responses to capsaicin were inhibited by the selective TRPV1 antagonist SB366791. The polymodal nociceptive neuron also responded to noxious thermal stimuli (>40°C), and this response was also blocked by SB366791. Capsaicin sensitivity was selective to the polymodal nociceptor with no direct response being elicited in the mechanical nociceptive neuron or in the non-nociceptive touch- or pressure-sensitive neurons. Capsaicin also elicited nocifensive behavioral responses (withdrawals and locomotion) in a concentration-dependent manner, and these behavioral responses were significantly attenuated with SB366791. These results suggest the presence of a capsaicin-sensitive TRPV-like channel in the medicinal leech central nervous system and are relevant to the evolution of nociceptive signaling.
瞬时受体电位香草酸亚型（TRPV）通道存在于整个动物界，在感觉转导中发挥重要作用。在本研究中，我们结合生理学研究与体内行为实验，以检验药用蛭中是否存在假定的TRPV样受体，该研究建立在此种冠轮动物门无脊椎动物早期研究的基础之上。药用蛭的多模式伤害性感受神经元可被TRPV1激活剂辣椒素外周和中枢给药以浓度依赖的方式激活，100 μmol l(-1)为最低有效浓度。对辣椒素的反应被选择性TRPV1拮抗剂SB366791抑制。多模式伤害性感受神经元对有害热刺激（>40°C）也有反应，且该反应也被SB366791阻断。辣椒素敏感性对多模式伤害感受器具有选择性，在机械性伤害感受神经元或非伤害性触觉或压力敏感神经元中未引发直接反应。辣椒素还以浓度依赖的方式引发伤害防御行为反应（退缩和运动），且这些行为反应被SB366791显著减弱。这些结果表明药用蛭中枢神经系统中存在对辣椒素敏感的TRPV样通道，并且与伤害性信号传导的进化相关。
