Keeble Julie Elizabeth, Brain Susan Diana
Cardiovascular Division, New Hunt's House, King's College London, Guy's Campus, SE1 1UL, UK.
Neurosci Lett. 2006 Jun 19;401(1-2):55-8. doi: 10.1016/j.neulet.2006.02.083. Epub 2006 Apr 3.
Capsaicin is the pungent component of chilli peppers that concomitantly activates and desensitizes C-fibre and Adelta sensory nerve fibres. Stimulation causes an acute neurogenic response including vasodilation, plasma extravasation and hypersensitivity. However, in the present study we have shown that capsaicin produces a dose-dependent vasoconstrictor effect in the mouse knee joint via Transient Receptor Potential Vanilloid 1 (TRPV1) receptor activation. A (125)I-albumin accumulation technique showed that the intravascular volume of capsaicin-treated joints in wild type (WT) mice was significantly reduced compared to TRPV1 knockout mice (p<0.01). Similarly, a laser Doppler technique showed significantly reduced blood flow in the capsaicin-treated joints of WT compared to TRPV1 knockout mice (p<0.001). Pretreatment with guanethinidine (50 mg kg(-1), i.p.) had no effect on the vasoconstriction. These data are important considering the involvement of TRPV1 receptors in joint disease. The mechanisms underlying the vasoconstriction therefore require further investigation.
辣椒素是辣椒中的辛辣成分，它能同时激活并使C纤维和Aδ感觉神经纤维脱敏。刺激会引发急性神经源性反应，包括血管舒张、血浆外渗和超敏反应。然而，在本研究中我们发现，辣椒素通过激活瞬时受体电位香草酸亚型1（TRPV1）受体，在小鼠膝关节中产生剂量依赖性血管收缩效应。一项碘（125）白蛋白蓄积技术显示，与TRPV1基因敲除小鼠相比，野生型（WT）小鼠中经辣椒素处理的关节的血管内容积显著减少（p<0.01）。同样，激光多普勒技术显示，与TRPV1基因敲除小鼠相比，野生型小鼠经辣椒素处理的关节中的血流显著减少（p<0.001）。用胍乙啶（50 mg kg(-1)，腹腔注射）预处理对血管收缩没有影响。考虑到TRPV1受体与关节疾病有关，这些数据很重要。因此，血管收缩的潜在机制需要进一步研究。
