Local intramuscular injection of a plasmid encoding human proenkepahlin attenuates incision pain in rats

• Published in: Neuroscience letters Vol. 632; pp. 157 - 162
• Main Authors: Hu, Chunsheng, Cai, Zhenzhen, Lu, Yuxin, Cheng, Xiaochen, Wu, Zuze, Zhang, Qinglin
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 06-10-2016
• Subjects: Animals; Enkephalins - therapeutic use; Gene therapy; Genetic Therapy; Incision; Injections, Intramuscular; Male; Pain - drug therapy; Pain Management - methods; Pain Threshold - drug effects; Plasmid; Plasmids; Postoperative pain; Proenkephalin; Protein Precursors - therapeutic use; Rats; Rats, Sprague-Dawley; Incision; Plasmid; Proenkephalin; Postoperative pain; Gene therapy
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2016.08.058

•Surgical incision resulted in mechanical allodynia and thermal hyperalgesia in rats.•Local intramuscular injection of pVAX1-PENK attenuated nocifensive behaviors.•Analgesic effect of pVAX1-PENK was blocked by methylnaltrexone.
We investigated the antinociceptive effect of local intramuscular injection of a plasmid encoding human proenkephalin (pVAX1-hPPE) on postoperative pain in rats. Male Sprague-Dawley rats with incision-induced pain were intramuscularly injected into injured plantaris muscle with empty vector (pVAX1) or pVAX1-hPPE, respectively. Paw mechanical threshold and thermal latency in the 200μg pVAX1-hPPE treated rats were significantly higher at 6h and on 1day, and lasted until day 7 after intramuscular administration, respectively. The analgesic effects were reversed by methylnaltrexone, suggesting that the antinociceptive effect of pVAX1-hPPE was mediated through peripheral opioid receptor pathway. In contrast, incisional or pVAX1-treated rats did not significantly affect pain thresholds. These results demonstrated that single intramuscular injection of pVAX1-hPPE attenuated incision-induced pain in rats, and it is worthy of further study as a potential gene therapy for postoperative pain.