Elevated prepronociceptin, nociceptin/orphanin FQ and nocistatin concentrations in rat chronic constriction nerve injury and diabetic neuropathic pain models.

Nociceptin/orphanin FQ (N/OFQ) and nocistatin are derived from the same precursor peptide, prepronociceptin. N/OFQ and nocistatin have been postulated to participate in pain modulation. In this study, we investigated whether the prepronociceptin, N/OFQ and nocistatin concentrations in the brain and spinal cord would be altered in chronic constriction injury and diabetic rat neuropathic pain models. Total brain and spinal cord lysates as well as serum from rats that had undergone chronic constriction injury and streptozocin-induced diabetic neuropathy were used to determine the concentrations of three peptides using competitive radioimmunoassay. We found that N/OFQ and prepronociceptin concentrations were significantly raised in both rat neuropathic pain models. Nocistatin was raised in the brains of post traumatic neuropathy pain rats. Overall, our data have demonstrated for the first time that prepronociceptin, N/OFQ and nocistatin concentrations are significantly altered at different tissues of two rat neuropathy pain models.