In these experiments mice were subjected to nociceptive testing of the hind paw to establish the baseline threshold

Mice were then pre-treated with either saline or morphine for 4 days prior to hind paw incisions being made. After incision, groups of mice were treated daily with daily intraperitoneal saline or pentoxifylline as described in Methods. Nociceptive testing 72 hours after hind paw incision (2 hours after the last dose of pentoxifylline). **p < 0.01, N = 8/group.<p><b>Copyright information:</b></p><p>Taken from "Chronic morphine administration enhances nociceptive sensitivity and local cytokine production after incision"</p><p>http://www.molecularpain.com/content/4/1/7</p><p>Molecular Pain 2008;4():7-7.</p><p>Published online 22 Feb 2008</p><p>PMCID:PMC2279109.</p><p>