Behavioral testing of minipigs transgenic for the Huntington gene—A three-year observational study

Abstract

BackgroundLarge animal models of Huntington’s disease (HD) may increase the reliability of translating preclinical findings to humans. Long live expectancy offers opportunities particularly for disease modifying approaches, but also challenges. The transgenic (tg) HD minipig model assessed in this study exhibits a high genetic homology with humans, similar body weight, and comparable brain structures. To test long-term safety, tolerability, and efficacy of novel therapeutic approaches in this model reliable assessments applicable longitudinally for several years are warranted for all phenotypical domains relevant in HD.ObjectiveTo investigate whether the tests proposed assessing motor, cognitive and behavioral domains can be applied repetitively over a 3-year period in minipigs with acceptable variability or learning effects and whether tgHD minipigs reveal changes in these domains compared to wildtype (wt) minipigs suggesting the development of an HD phenotype.MethodsA cohort of 14 tgHD and 18 wt minipigs was followed for three years. Tests applied every six months included a tongue coordination and hurdle test for the motor domain, a color discrimination test for cognition, and a dominance test for assessing behavior. Statistical analyses were performed using repeated ANOVA for longitudinal group comparisons and Wilcoxon-tests for intra-visit differences between tgHD and wt minipigs.ResultsAll tests applied demonstrated feasibility, acceptable variance and good consistency during the three-year period. No significant differences between tgHD and wt minipigs were detected suggesting lack of a phenotype before the age of four years.ConclusionsThe assessment battery presented offers measures in all domains relevant for HD and can be applied in long-term phenotyping studies with tgHD minipigs. The observation of this cohort should be continued to explore the timeline of phenotype development and provide information for future interventional studies.

Longitudinal study revealing motor, cognitive and behavioral decline in a transgenic minipig model of Huntington's disease

“…The number of reached holes, and their depth, was similar to that of WT controls. Similarly, in a previous study, no significant changes were detected in TgHD sows up to 40 months of age (Schuldenzucker et al, 2017). We suppose that this could be an effect of housing TgHD and WT sows in shared pens, in which the dominant WT sow(s) could eat more food than the TgHD sows, causing the TgHD sows to feel hungrier and therefore more motivated to reach for the treat.…”

“…All of the examined animals from F0-F3 generations carried one copy of the mHTT gene with 124 mixed CAG/CAA repeats incorporated in chromosome 1. Previously, no significant difference was observed between TgHD and WT sows up to 40 months of age (Schuldenzucker et al, 2017). A significant decline in the ability to perform the tunnel test, and a general tendency (non-significant) for reduced accomplishment in other motor, behavioral and cognitive tests, was detected in a mixed group of TgHD males and females at the age of 48 months (Askeland et al, 2018).…”

“…used in WT sheep (McBride et al, 2016) and TgHD minipigs (Schuldenzucker et al, 2017). No significant differences in a choice discrimination test or in a dominance test, which was used to test dominant/aggressive behavior in TgHD sows up to 40 months of age (Schuldenzucker et al, 2017), were observed.…”

“…This study aimed to longitudinally monitor the motor, cognitive and behavioral phenotype of TgHD minipigs up to 8 years. Gait, hurdle and startbox back-and-forth tests using TgHD minipigs were established in the George-Huntington-Institute in Münster (Schramke et al, 2016;Schuldenzucker et al, 2017). Activity was measured by a telemetric system adapted for minipigs, and cover and skittle toys for cognitive measures, and a balance beam and seesaw for stress-induced tests, were established by us.…”

Electrophysiological Signature Reveals Laminar Structure of the Porcine Hippocampus

“…Due to their gyrencephalic brains and substantial white matter, pigs have been used to model CNS disorders such as TBI and epilepsy (Van Gompel et al, 2011), and may be useful for other hippocampal centric models of cognitive dysfunction (Maas et al, 2017;Rollin, 2006). Further, these models are strengthen by the growing number of studies conducted to measure cognitive performance in pigs (Asher et al, 2016;Broom et al, 2009;Conrad and Johnson, 2015;Fleming and Dilger, 2017;Gieling et al, 2011a;Gieling et al, 2011b;Grimberg-Henrici et al, 2016;Schramke et al, 2016;Schuldenzucker et al, 2017;Sullivan et al, 2013).…”