Intramuscular electroporation with the pro-opiomelanocortin gene in rat adjuvant arthritis.
Endogenous opioid peptides have an essential role in the intrinsic modulation and control of inflammatory pain, which could be therapeutically useful. In this study, we established a muscular electroporation method for the gene transfer of pro-opiomelanocortin (POMC) in vivo and investigated its effect on inflammatory pain in a rat model of rheumatoid arthritis. The gene encoding human POMC was inserted into a modified pCMV plasmid, and 0-200 microg of the plasmid-POMC DNA construct was transferred into the tibialis anterior muscle of rats treated with complete Freund's adjuvant (CFA) with or without POMC gene transfer by the electroporation method. The safety and efficiency of the gene transfer was assessed with the following parameters: thermal hyperalgesia, serum adrenocorticotropic hormone (ACTH) and endorphin levels, paw swelling and muscle endorphin levels at 1, 2 and 3 weeks after electroporation. Serum ACTH and endorphin levels of the group into which the gene encoding POMC had been transferred were increased to about 13-14-fold those of the normal control. These levels peaked 1 week after electroporation and significantly decreased 2 weeks after electroporation. Rats that had received the gene encoding POMC had less thermal hypersensitivity and paw swelling than the non-gene-transferred group at days 3, 5 and 7 after injection with CFA. Our promising results showed that transfer of the gene encoding POMC by electroporation is a new and effective method for its expression in vivo, and the analgesic effects of POMC cDNA with electroporation in a rat model of rheumatoid arthritis are reversed by naloxone.
Gene Therapy Laboratory, Tajen Institute of Technology, Pingtung, 907, Taiwan. lcyang1@ms13.hinet.net
I-Chuan
IC
Chuang
Chien-Ming
CM
Jhao
Chih-Hsun
CH
Yang
Hsien-Chang
HC
Chang
Chien-Wen
CW
Wang
Cheng-Yuan
CY
Lu
Yao-Jen
YJ
Chang
Sheng-Han
SH
Lin
Pao-Lin
PL
Huang
Lin-Cheng
LC
Yang