“…Thus, the up-regulation of MOR1 in the Q175KI striatum is an early change, suggesting that it might not be, at least initially, solely compensatory. Also, this change is a histological confirmation of instances of upregulation, as opposed to down-regulation, of neuronal proteins seen in proteomic and PET studies in HD and in the Q175KI HD model (Ferrante et al, 1985(Ferrante et al, , 1987Reiner et al, 1988Reiner et al, , 2013Goto et al, 1989;Albin et al, 1990Albin et al, , 1992Morton et al, 1993;Hedreen and Folstein, 1995;Augood et al, 1996;Cicchetti et al, 2000;Tippett et al, 2007;Smith et al, 2014;Langfelder et al, 2016;Wilson et al, 2017;Padovan-Neto et al, 2019). Given that MOR1 mRNA in Q175KI mice was not up-regulated in the striatum at the age of 2, 6, and 10 months (Langfelder et al, 2016), as judged by immunohistochemistry, MOR1 up-regulation in our study may be thought to occur in posttranscriptional or posttranslational manner, for example, due to dysregulation in alternative splicing, the consequence of protein-protein interaction, or compensation to the changes in the expression levels in other proteins.…”