Whelan, Patrick J.Ozogbuda, Prince Nyekazi2018-07-032018-07-032018-06-21Ozogbuda, P. N. (2018). Neuromodulatory Effect of Kappa Opioid Receptor Activation on Spinal Network Activity (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/32047http://hdl.handle.net/1880/106825Dynorphin is a potent anti-nociceptive neuropeptide ubiquitously expressed throughout the peripheral and central nervous system. Previous studies have shown that dynorphin is co-packaged and co-released with orexin, a pro-locomotory neuropeptide known to be involved in goal-directed movement. Why then is an inhibitory neuropeptide co-released with an excitatory pro-locomotory neuropeptide orexin, and what is its role? In this thesis, the expression of kappa opioid receptors (KOR) on motoneurons was demonstrated using RNAscope Assay. Consistent with the observation of other studies, my results show that KOR activation significantly reduced spontaneous network activity, increased motoneuron excitability, and increased presynaptic inhibition. These results suggest that dynorphin modulates the spinal motor network rather than inhibits it. This also explains why the co-release of orexin and dynorphin does not have an antagonistic effect. My work suggests that perinatally dynorphin can have potent effects on spinal cord networks. This raises the possibility that dynorphin release may contribute to the development and correct function of spinal cord motor networks.engUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.Dynorphinspinal cordlocomotionmotoneuronkappa opioid receptorU69,593Neurosciencemaster thesis10.11575/PRISM/32047