Hayati Ahmad Asma, Zalina Ismail, Myo Than, Badariah Abdul Aziz Che, Azhar Ahmad, Idris Long
Department of Physiology, School of Medical Sciences, Health Campus, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia.
Ger Med Sci. 2008 Jun 30;6:Doc05.
Induction of c-fos in the spinal cord due to pain is well established. This study aims to look at the effects of acute swim stress on Fos-like immunoreactivity (FLI) induced by formalin and how it is modulated by ketamine and morphine. Acutely-stressed and non-stressed adult male Sprague Dawley rats were pretreated with intraperitoneal injection of ketamine 5 mg/kg (Ketava, Atlantic Lab), morphine 10 mg/kg (Rhotard, Custom Pharmaceutical), or saline, 5 minutes prior to experimentation. Rats were acutely stressed by swimming for 3 min in 20 degrees C water. Dilute formalin (Formaldehyde, Merck) was injected to the hindpaw and the formalin score recorded. Rats were then sacrificed and spinal cords (L4-L5) removed for immunohistochemical analysis of FLI. Two-way ANOVA showed significant effects of stress, drug and stress-drug interactions in formalin test and FLI. Both morphine and ketamine produced analgesia in the formalin test. In the saline stressed group, FLI was suppressed on the ipsilateral side (p<0.01) but increased on the contralateral side (p<0.01) compared with non-stressed saline. In morphine and ketamine stressed groups, FLI was increased on both ipsilateral and contralateral sides for morphine (ipsilateral: p<0.05; contralateral: p<0.001) and ketamine (ipsilateral: p<0.05, contralateral: p<0.05) compared with their corresponding non-stressed groups. In conclusion, presence of stress may lead to discrepancy between behavioural manifestation of pain and c-fos induction in the spinal cord.
疼痛导致脊髓中c-fos的诱导已得到充分证实。本研究旨在观察急性游泳应激对福尔马林诱导的Fos样免疫反应性（FLI）的影响，以及氯胺酮和吗啡对其的调节作用。在实验前5分钟，对急性应激和非应激的成年雄性Sprague Dawley大鼠腹腔注射5 mg/kg氯胺酮（Ketava，Atlantic Lab）、10 mg/kg吗啡（Rhotard，Custom Pharmaceutical）或生理盐水进行预处理。通过在20摄氏度的水中游泳3分钟使大鼠急性应激。将稀释的福尔马林（甲醛，默克）注射到后爪并记录福尔马林评分。然后处死大鼠，取出脊髓（L4-L5）进行FLI的免疫组织化学分析。双向方差分析显示，在福尔马林试验和FLI中，应激、药物及应激-药物相互作用具有显著影响。吗啡和氯胺酮在福尔马林试验中均产生镇痛作用。与非应激生理盐水组相比，生理盐水应激组同侧的FLI受到抑制（p<0.01），但对侧增加（p<0.01）。与相应的非应激组相比，吗啡和氯胺酮应激组同侧和对侧的FLI均增加，吗啡组同侧（p<0.05；对侧：p<0.001），氯胺酮组同侧（p<0.05，对侧：p<0.05）。总之，应激的存在可能导致疼痛行为表现与脊髓中c-fos诱导之间的差异。
