The effect of formalin-induced pain on CCK in rat spinal cord neurons / 中国应用生理学杂志

ABSTRACT

<p><b>AIM</b>CCK is one of the strongest endogenous anti-opioid substances and suppresses morphine tolerance which results from long term use of morphine. This study explores the modulatory effect of CCK on pain formalin-induced.</p><p><b>METHODS</b>The effect of formalin-induced pain on CCK immunoreactivity in rat sensory neurons was observed through immunohistochemistry technique.</p><p><b>RESULTS</b>After 1 h of subcutaneous injection of formalin in one paw of rats, the number of positive neurons of CCK immunoreactivity in spinal cord neurons was obviously increased and greater than that of non-injection side (P <0.01). The semi-quantitative optical density average values of CCK immunoreactivity neurons were 0.397 +/- 0.014 and 0.295 +/- 0.007 in injection side and non-injection side respectively, the difference was obvious (P < 0.01). After 3 h of subcutaneous injection of formalin in one paw of rats, the semi-quantitative optical density average values of CCK immunoreactivity neurons were 0.366 +/- 0.009 and 0.303 +/- 0.005 in injection side and noninjection side respectively, the difference was significant (P < 0.01).</p><p><b>CONCLUSION</b>Formalin-induced pain can significantly change semi-quantitative optical density average value of CCK immunoractivity in spinal cord neurons, this indicates CCK participates in modulation of pain.</p>