Hitomi Suzuro, Ono Kentaro, Miyano Kanako, Ota Yojiro, Uezono Yasuhito, Matoba Motohiro, Kuramitsu Sachiko, Yamaguchi Kiichiro, Matsuo Kou, Seta Yuji, Harano Nozomu, Inenaga Kiyotoshi
Division of Physiology, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580, Japan.
Division of Cancer Pathophysiology, National Cancer Center Research Institute, 5-1-1, Tsukiji, Chuo-ku, Tokyo 104-0045, Japan.
J Neurosci Methods. 2015 Jan 15;239:162-9. doi: 10.1016/j.jneumeth.2014.10.013. Epub 2014 Oct 29.
Stomatitis induces severe and painful hypersensitivity to pungency and physical contact during meals. Many studies have used anesthetized animals to examine evoked nociception in the oral mucosa, but no reports have used traditional behavioral assays to evaluate nociception in conscious animals.
We developed two new methods of applying chemical or mechanical stimulation directly to the oral mucosa of the mandibular vestibule of conscious rats. Nociceptive evaluations were performed by measuring facial grooming time and the head withdrawal threshold to von Frey stimulations. (1) For the intraoral dropping method, rat mucosa was transiently exposed by hand, and a drop of a pungent solution was applied. (2) For the stable intraoral opening method, rat mucosa was long-term exposed following piercing surgery of the mental skin after habitual training for 2-3 weeks.
In the intraoral dropping method, the application of 100 μM capsaicin or 100 mM allyl isothiocyanate prolonged mouth-rubbing time. Capsaicin-induced mouth-rubbing time was further enhanced following the development of an acetic acid-induced ulcer. The stable intraoral opening method enabled stable measurements of the mechanical withdrawal threshold in the oral mucosa of conscious rats. Ulcer development decreased the mechanical threshold, whereas topical lidocaine treatment increased the threshold.
These new methods enable the evaluations of motivational nocifensive behaviors in response to intraoral stimulations without any anesthetic effects.
The intraoral dropping and stable intraoral opening methods can be used in combination with traditional behavioral assays to evaluate nociception in the oral mucosa of conscious rats.
口腔炎会在进食期间引发对辛辣味道和物理接触的严重且疼痛的超敏反应。许多研究使用麻醉动物来检测口腔黏膜中的诱发伤害感受，但尚无报告使用传统行为学方法来评估清醒动物的伤害感受。
我们开发了两种直接对清醒大鼠下颌前庭口腔黏膜施加化学或机械刺激的新方法。通过测量面部梳理时间和对冯·弗里刺激的头部撤离阈值来进行伤害感受评估。（1）对于口腔内滴注法，用手短暂暴露大鼠黏膜，然后滴加一滴辛辣溶液。（2）对于稳定口腔张开法，在经过2至3周的习惯训练后，对颏部皮肤进行穿刺手术，使大鼠黏膜长期暴露。
在口腔内滴注法中，应用100μM辣椒素或100mM异硫氰酸烯丙酯会延长擦嘴时间。在乙酸诱导的溃疡形成后，辣椒素诱导的擦嘴时间进一步延长。稳定口腔张开法能够稳定测量清醒大鼠口腔黏膜的机械撤离阈值。溃疡形成会降低机械阈值，而局部利多卡因治疗会提高阈值。
这些新方法能够在没有任何麻醉作用的情况下评估对口腔内刺激的动机性伤害防御行为。
口腔内滴注法和稳定口腔张开法可与传统行为学方法结合使用，以评估清醒大鼠口腔黏膜的伤害感受。
