Splenectomy before or immediately after
stroke provides early brain protection. This study aims to explore the effect of
splenectomy on long-term neurological recovery after
stroke, which is currently lacking in the field. Adult male rats were randomized into
splenectomy or
sham groups and then subjected to 90 min of
middle cerebral artery occlusion (MCAO). Spleen was removed right upon reperfusion or 3d after MCAO.
Infarct volume, neurological functions, and peripheral immune cell populations were assessed up to 28d after
stroke. The results show that delayed removal of spleen did not reduce brain tissue loss and showed no effect on sensorimotor function (Rotarod, beam balance, forelimb placing, grid walk, and adhesive removal tests) or cognitive function (Morris water maze). Spleen removal immediately upon reperfusion, although significantly reduced the
infarct size and immune cell infiltration 3d after MCAO, also failed to promote long-term recovery. Flow cytometry analysis demonstrated that immediate
splenectomy after MCAO resulted in a prolonged decrease in the percentage of CD3+CD4+ and CD3+CD8+ T cells in total lymphocytes as compared to non-
splenectomy MCAO rats. In contrast, the percentage of CD3-CD45RA+ B cells was significantly elevated after
splenectomy. As a result, the ratio of T/B cells was significantly reduced in
stroke rats with
splenectomy. In conclusion, delayed
splenectomy failed to provide long-term protection to the ischemic brain or improve functional recovery. The acute
neuroprotective effect achieved by early
splenectomy after
stroke cannot last for long term. This loss of neuroprotection might be related to the prolonged disturbance in the T cell to B cell ratio.