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Int J Clin Exp Pathol 2012;5(9):914-923

Original Article
Effect of recombinant adenovirus coding for endomorphin-2 on neuropathic pain in rats

Feixiang Wu, Xuewu Xu, Xuerong Miao, Jiaying Chen, Yuming Sun, Weifeng Yu

Department of Anesthesiology, Eastern Hepatobiliary Hospital, Shanghai 200433, China; Department of Anesthesiology, Hospital 306, Beijing
100101, China. *Equal contributors.

Received August 18, 2012; Accepted September 24, 2012; Epub October 20, 2012; Published October 30, 2012

Abstract: Objective: To construct a transgene expressing human endomorphin-2 by linking the signal peptide of mouse nerve growth factor
(PN) to a human endomorphin-2 DNA sequence containing a short linker recognized by the protease FURIN and test the analgesic effect of
endomorphin-2 on neuropathic pain. Methods: The transgene was inserted into the cosmid pAxCAwt to generate PN-EM-2-pAxCAwt. The
recombinant adenovirus Ad-PNEM2 was packaged and propagated in HEK293 cells. After the Ad-PNEM2-infected NIH3T3 cells had been
cultured, protein expression was examined by immunofluorescence and ELISA. A CCI rat model was constructed and the Ad-PNEM2 was
administered intrathecally. The rats’ pain thresholds (PWL) were measured and the presence of endomorphin-2 in the cerebrospinal fluid was
confirmed through ELISA. Results: The Ad-PNEM2 expressed endomorphin-2 smoothly and abundantly in NIH3T3 cells at a significantly higher
rate than the viral control (P<0.01) or blank control (P<0.01). The expressed endomorphin-2 was mainly observed in the cytoplasm. The
concentration of endomorphin-2 in the cerebrospinal fluid increased 1 day after injection and peaked between 7 and 14 days after injection.
After injection, PWL approached normal levels in the operated study group. No significant change was observed in the control groups. There
was a significant correlation between PWL and endomorphin-2 level (r = 0.944, P<0.001). Conclusion: The constructed human endomorphin-2
transgene was expressed effectively, and endomorphin-2 expressed by the recombinant adenovirus altered the threshold to thermal stimulus
and showed good analgesic effect. (IJCEP1208017).

Keywords: Endomorphin-2, nerve growth factor, adenovirus, pain, gene therapy

Address all correspondence to:
Dr. Weifeng Yu
Department of Anesthesiology
Eastern Hepatobiliary Hospital
Changhai Road 225, Yangpu District
Shanghai 200433, China.
Tel/Fax: +86 2125070783
E-mail: ywf808@smmu.edu.cn