Fundamental & clinical pharmacology
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Fundam Clin Pharmacol · Jun 2014
Effects of tramadol on viscero-visceral hyperalgesia in a rat model of endometriosis plus ureteral calculosis.
The effects of tramadol versus placebo administration on behavioral indicators of ureteral pain, pelvic pain and referred lumbar muscle hyperalgesia were investigated in a rat model of viscero-visceral hyperalgesia from endometriosis plus ureteral calculosis (endo + stone). Fifty female Sprague-Dawley rats underwent surgical induction of endometriosis and, 2 weeks later, were randomly assigned to five groups (10 each), to be treated i.p., twice a day, with tramadol (0.625, 1.25, 2.5, or 5 mg/kg) or saline for 5 days (14-18th day postendometriosis; prestone treatment). On the 21st day, they underwent laparotomy for stone formation in the upper left ureter (dental cement injection). ⋯ Tramadol vs. saline significantly reduced number and duration of ureteral crises, duration of pelvic behavior, and incidence of muscle hyperalgesia (P < 0.0001), with a dose-dependent effect. Prestone treatment was significantly more effective than poststone treatment for the 1.25 dose for all parameters and 2.5 dose for pelvic and muscle parameters (0.003 > P < 0.02). Tramadol, even at low doses, is thus highly protective against pain from 'viscero-visceral hyperalgesia' in endometriosis plus ureteral calculosis; it can represent a valid therapeutic approach in women with these comorbidities.