Background/aims: Many stroke survivors are left with permanent upper limb motor disability. To effectively test new motor training interventions, our team is developing a preclinical platform that models clinically relevant upper limb deficits poststroke. The aim of this pilot study was to determine the optimal length of light exposure to induce forelimb motor deficits following photothrombotic (PT) stroke in C57BL/6J mice.
Method: PT stroke was induced by administering Rose Bengal dye intraperitoneally followed by illumination of the skull with cold light over the primary motor cortex. Light exposure was set at 15 (n=3), 18 (n=3) or 21-minutes (n=2). Sham controls (n=3) were injected with Rose Bengal dye but not exposed to light. Three days post-lesion mice were assessed using the horizontal grid test and the cylinder test to assess forelimb motor function. Data are reported descriptively as mean + SEM.
Results: PT stroke led to a progressive increase in foot-slips with increasing duration of light exposure: sham (3.77 +/- 0.90), 15-min PT stroke (6.29 +/- 0.63), 18-min (10.57 +/- 0.60) and 21-min (11.91 +/- 3.50). A slight reduction in forelimb asymmetry was observed following the 21-min light exposure (sham: 51.63 +/- 9.51%; 21-min PT: 47.91 +/- 11.07%).
Conclusion: This pilot study demonstrates that 18-21-min light exposure for the PT model is optimal for inducing severe forelimb motor impairments in mice. These findings will be leveraged to develop a preclinical platform for evaluating upper limb rehabilitation strategies. Future model developments also aim to incorporate components of reperfusion linked to thrombolysis.