Alterations In The Activity Of Spinal And Thalamic Opioid Systems In A Mice Neuropathic Pain Model

Publication date: Available online 1 September 2018Source: NeuroscienceAuthor(s): Ewelina Rojewska, Agnieszka Wawrzczak-Bargiela, Edina Szucs, Sandor Benyhe, Joanna Starnowska, Joanna Mika, Ryszard Przewlocki, Barbara PrzewlockaAbstractClinical studies have reported lower effectivity of opioid drugs in therapy of neuropathic pain. Therefore, to determine the changes in endogenous opioid systems in this pain more precisely, we have studied the changes in the pain-related behaviour on days 1, 14, and 28 following a chronic constriction injury (CCI) to the sciatic nerve in mice. In parallel, we have studied the changes of -(MOP), -(DOP) and -(KOP) receptors, proenkephalin (PENK) and prodynorphin (PDYN) mRNA levels, as well as GTPĪ³S binding of opioid receptors on the ipsi- and contralateral parts of the spinal cord and thalamus on the 14th day following CCI, as on this day the greatest manifestation of pain-related behaviour was observed. On ipsilateral spinal cord, the decrease in MOP/DOP/KOP receptor and increase in PDYN/PENK mRNA expression was observed. In thalamus, MOP/DOP/KOP receptor expression decreased contralaterally. On ipsilateral side, there were no changes in PDYN/PENK or DOP/KOP receptor expression, but MOP mRNA decreased. The spinal GTP S binding of MOP/DOP/KOP receptor ligands decreased on the ipsilateral side, yet the effect was less pronounced for DOP receptor ligands. In thalamus, a decrease was observed on the contralateral side for all opioid receptor ligan...
Source: Neuroscience - Category: Neuroscience Source Type: research