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[BKCa channel agonist NS1619 and Kv channel antagonist 4-AP on the facial mechanical pain threshold in a rat model of chronic constriction injury of the infraorbital nerve.] [Ariticle in Chinese]

LIU Cai-Yue, LI Na, ZHAO Yun-Fu, MA Bei

Department of Physiology, the Second Military Medical University, Shanghai 200433, China； Department of Stomatology, Changzheng Hospital, Shanghai 200003, China； 3Department of Anesthesia, No. 59 Hospital of Chinese People’s Liberation Army, Kaiyuan 661600, China

Abstract

Trigeminal neuralgia is a paroxysmal disorder with severely disabling facial pain and thus continues to be a real therapeuticchallenge. At present there are few effective drugs for treatment of this pain. The present study was aimed to explore the involvementof BKCa channels and Kv channels in the mechanical allodynia in a rat model of trigeminal neuropathic pain. Here the effectiveness ofdrug target injection at the trigeminal ganglion through the infraorbital foramen was first evaluated by immunofluorescence and animalbehavior test. Trigeminal neuropathic pain model was established by chronic constriction injury of the infraorbital nerve (ION-CCI) inrats. BKCa channel agonist and Kv channel antagonist were administered into the trigeminal ganglion in ION-CCI rats and sham rats by the above target injection method, and the facial mechanical pain threshold was measured. The results showed that the drug couldaccurately reach the trigeminal ganglion by target injection which was more effective than that by the normal injection around infraorbitalforamen. Rats suffered significant mechanical allodynia in the whisker pad of the operated side from 6 d to 42 d after ION-CCI.BKCa channel agonist NS1619 significantly and dose-dependently attenuated the facial mechanical allodynia and increased the facialmechanical pain threshold in ION-CCI rats 15 d after operation. Kv antagonist 4-AP was able to reduce the threshold in ION-CCI ratswhen facial mechanical threshold was partly recovered and relatively stable on the 35th day after operation. These results suggest thatBKCa channel agonist NS1619 and Kv channel antagonist 4-AP can significantly affect the rats’ facial mechanical pain threshold afterION-CCI. Activation of BKCa channels may be related to the depression of the primary afferent neurons in trigeminal neuropathic painpathways. Activation of Kv channels may exert a tonic inhibition on the trigeminal neuropathic pain.

Key words: ION-CCI; neuropathic pain; trigeminal ganglion; target injection; NS1619; 4-AP

Received: 2010-07-05　　Accepted: 2010-08-02

Corresponding author: 赵云富　　E-mail: zhaoyf1818@126.com

Citing This Article：

LIU Cai-Yue, LI Na, ZHAO Yun-Fu, MA Bei. [BKCa channel agonist NS1619 and Kv channel antagonist 4-AP on the facial mechanical pain threshold in a rat model of chronic constriction injury of the infraorbital nerve.] [Ariticle in Chinese] . Acta Physiol Sin 2010; 62 (5): 441-449 (in Chinese with English abstract).