Abstract Body: Background: The variations in stroke volume are large and behavioral deficits are short-lived in rodent stroke models. These issues pose a challenge when using a rodent stroke model to test therapeutic interventions. The objective of this study is to explore composite analysis of multi-category behavioral outcomes for increasing the drug testing utility of the mouse middle cerebral artery occlusion (MCAO) model.

Methods: Mice were subjected to 0 (sham), 20, 40, and 60 min MCAO, followed by 21 days of recovery. The rCBF was maintained at <10% of the normal level during MCAO. The naturally occurring post-MCAO hypothermia was corrected by a heating pad. Three outcomes (bodyweight for physical recovery; nesting for daily activity; and pole test for motor function) were documented at day-3, -7, -10, -14, and -21 post-MCAO. Dead mice were either excluded from analysis or imputed by assigning the worst score in the behavioral analysis. For the composite analysis, each sham mouse was assigned 33.3% per outcome, i.e., 100% per combination of the three outcome categories. Accordingly, relative to the sham value, the deficit percentage per outcome in each 20, 40, and 40 min MCAO mouse was calculated. The stroke volume was assessed at the 21-day endpoint. The relationships among stroke volume and behavioral outcomes were analyzed.

Results: There is a positive relationship between stroke volume and behavioral deficits post-MCAO. Because of the limit of 10% rCBF during MCAO and post-MCAO hypothermia correction, the mortality rate reached to 80% in 60, 57% in 40, but 0% in 20 min MCAO group. When dead mice were excluded, the differences in mortality and behavioral deficits were statistically significant in all three category outcomes among 0 (sham), 20, 40, and 60 min MCAO groups before 7-day, but became insignificant after 7-day post-MCAO. When dead mice were imputed, the statistical significance in all three category deficits also become apparent after 7-day post-MCAO. Compared to the individual deficit analysis, the composite analysis of multi-category behavioral deficits further increases the statistical significance of behavioral outcomes post-MCAO.

Conclusion: Stroke volume has a positive correlation only with imputed behavioral deficits post-MCAO. Compared to the individual analysis, the multi-category composite analysis can further increase the statistical significance of the behavioral outcomes post-MCAO or translational usefulness of the mouse model.