Protective Effect of Palmitoylethanolamide in a Rat Model of Cystitis

Purpose: PEA is an endogenous mediator released together with the endo-cannabinoid anandamide from membrane phospholipids. It is a plant derived compound with analgesic and anti-inflammatory properties. We verified whether the pathophysiology of experimental cystitis involves changes in the levels of PEA and of some of its targets, ie CB1 and CB2 receptors, and PPAR. We also determined whether exogenously administered PEA could be proposed as a preventive measure for cystitis. Materials and Methods: Cystitis was induced by cyclophosphamide in female rats. Nociceptive responses, voiding episodes, gross damage, myeloperoxidase activity, bladder weight, bladder PEA and endocannabinoid levels (measured by liquid chromatography-mass spectrometry) and the expression of PEA targets (measured by quantitative reverse transcriptase-polymerase chain reaction) were recorded. Results: Cyclophosphamide induced pain behavior, bladder inflammation and voiding dysfunction associated with increased bladder levels of PEA, up-regulation of CB1 receptor mRNA expression, down-regulation of PPARa mRNA and no change in CB2 receptor mRNA expression. Exogenously administered, ultramicronized PEA attenuated pain behavior, voids and bladder gross damage. The CB1 antagonist rimonabant and the PPARa antagonist GW6471 counteracted the beneficial effect of PEA on gross damage. Also, GW6471 further decreased voiding episodes in rats treated with PEA. Conclusions: The current study provides strong evidence for a protective role of PEA as well as an alteration in bladder levels of PEA and of some of its targets in cyclophosphamide induced cystitis.