Immunohistochemical Quantification of 5HT2C Receptors and CaV 1.3 Channels after Spinal Cord Injury in the Upper Lumbar Mouse Spinal Cord
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Van Patten, Gabrielle N.
The mammalian hindlimb central pattern generator (CPG) for locomotion is located in the lumbar spinal cord, and coordinates contralateral alternation of the hindlimbs and intralimb flexor/extensor muscle alternations. Serotonin (5HT) plays an important role in enabling CPG functionality. All serotonergic input to the lumbar cord descends from the medullary Raphe nuclei; these inputs are lost after a complete spinal cord lesion. We used immunohistochemical methods to determine whether spinal cord injury (SCI) affects the expression levels of 5HT2C receptor clusters and CaV 1.3 channel clusters. Quipazine is a 5HT2 agonist and its regular administration has previously led to partial locomotor recovery. We sought to determine if daily administration would reduce the SCI-induced homeostatic changes in 5HT2C receptor and CaV 1.3 channel levels. Half the SCI mice were treated with quipazine, and half were saline vehicle treated. A combination of ImageJ and Matlab was used to determine the number, size, and intensity of 5HT2C receptor clusters after SCI, as well as the percentage of the frame area covered by CaV 1.3 channels and their average brightness. After SCI, there is a significant upregulation in the number of 5HT2C receptor clusters, and 5HT2C receptor clusters are significantly larger. Neither is reduced by quipazine. There is no significant change in the average brightness of 5HT2C receptor clusters after SCI. Additionally, the area and intensity of CaV 1.3 channels are significantly larger in SCI/saline mice than in intact mice. CaV 1.3 channels were not examined in SCI/quipazine mice due to a small sample size.
dissertation or thesis