Buprenorphine hydrochloride

Buprenorphine hydrochloride (Tocris Bioscience, Bristol, UK) was administered to sham and SNI surgery animals intraperitoneally (i.p.) at 25 μg/kg starting 1 hour before behavioral testing on post-operative days 8 and 11. Gabapentin (MilliporeSigma, St. Louis, MO) was administered to sham and SNI surgery animals at 30 mg/kg i.p. 1 hour prior to testing on post-operative days 11 and 20, and carprofen (Zoetis, Inc., Kalamazoo, MI) was administered Saline and CFA-injected animals at 5 mg/kg i.p., starting 1 hour prior to testing on days 2, 4 and 5 following saline/CFA injection. Drugs were dissolved in sterile saline to achieve final concentration. Control animals received equivalent volume of sterile saline administration (i.p.) as vehicle groups. These effective drug doses are derived from studies showing the effective dose of these drugs that attenuate pain-related behaviors in rodents with specific pain pathologies (Decosterd, Allchorne et al. 2004 (link), Christoph, Kogel et al. 2005 (link), Adamson, Kendall et al. 2010 (link), Smeester, Lee et al. 2017 (link)).

Buprenorphine hydrochloride (Tocris UK), ethanol (Sigma Aldrich UK), methadone hydrochloride (Sigma Aldrich UK) and morphine hydrochloride (Macfarlane Smith) were dissolved in sterile saline. 75 mg morphine alkaloid pellets and placebo pellets were obtained from the National Institute on Drug Abuse (Bethesda, MD). Heparin (Sigma Aldrich UK) was dissolved in distilled water.