Ipsilateral versus bilateral limb-training in promoting the proliferation and differentiation of endogenous neural stem cells following cerebral infarction in rats

Abstract

We investigated the effects of ipsilateral versus bilateral limb-training on promotion of endogenous neural stem cells in the peripheral infarct zone and the corresponding cerebral region in the unaffected hemisphere of rats with cerebral infarction. Middle cerebral artery occlusion was induced in Wistar rats. The rat forelimb on the unaffected side was either wrapped up with tape to force the use of the paretic forelimb in rats or not braked to allow bilateral forelimbs to participate in training. Daily training consisted of mesh drum training, balance beam training, and stick rolling training for a total of 40 minutes, once per day. Control rats received no training. At 14 days after functional training, rats receiving bilateral limb-training exhibited milder neurological impairment than that in the ipsilateral limb-training group or the control group. The number of nestin/glial fibrillary acidic protein-positive and nestin/microtubule-associated protein 2-positive cells in the peripheral infarct zone and in the corresponding cerebral region in the unaffected hemisphere was significantly higher in rats receiving bilateral limb-training than in rats receiving ipsilateral limb-training. These data suggest that bilateral limb-training can promote the proliferation and differentiation of endogenous neural stem cells in the bilateral hemispheres after cerebral infarction and accelerate the recovery of neurologic function. In addition, bilateral limb-training produces better therapeutic effects than ipsilateral limb-training.

Keywords: affected limb; bilateral limbs; bilateral rehabilitation training; brain; differentiation; middle cerebral artery occlusion; neural regeneration; neural stem cells; peripheral infarct zone; plasticity; proliferation; unaffected hemisphere.

Figure 1

Effects of different physical training regimes on cerebral infarct volume in rats. Data are expressed as mean ± SD (n = 8 rats per group per time point). One-way analysis of variance was used to compare differences between the groups. Cerebral infarct volume was calculated by cerebral infarct volume/whole-brain volume × 100%.

Figure 2

Nestin/glial fibrillary acidic protein (GFAP)-positive cells in the peripheral infarct zone in middle cerebral artery occlusion rats following ipsilateral or bilateral limb-training. In the gross specimen, the white area represents the cerebral infarction area. Nestin-positive cells are stained green. GFAP-positive cells are stained red. In the cytoplasm, the nestin/GFAP-positive cells were mainly yellow. The number of nestin/GFAP-positive cells in the ipsilateral limb-training group and bilateral limb-training group was significantly higher than that in the untreated group at postoperative day 3, and this effect lasted until postoperative day 14 (^aP < 0.05, vs. untreated group). There was no significant difference between the ipsilateral limb-training group and the bilateral limb-training group (P > 0.05). Data are expressed as mean ± SD (n = 8 rats per group per time point). One-way analysis of variance was used to compare differences between the groups.

Figure 3

Nestin/microtubule-associated protein-2 (MAP2)-positive cells in the peripheral infarct zone in middle cerebral artery occlusion rats following ipsilateral or bilateral limb-training. In the gross specimen, the white area represents the cerebral infarction area. Nestin-positive cells are stained green. MAP2-positive cells are stained red. In the cytoplasm, the nestin/MAP2-positive cells were mainly yellow. ^aP < 0.05, vs. untreated group. Data are expressed as mean ± SD (n = 8 rats per group per time point). One-way analysis of variance was used to compare differences between the groups.

Figure 4

Nestin/glial fibrillary acidic protein (GFAP) in the unaffected hemisphere in middle cerebral artery occlusion rats following ipsilateral or bilateral limb-training. In the gross specimen, the white area represents the cerebral infarction area. Nestin-positive cells are stained green. GFAP-positive cells are stained red. In the cytoplasm the nestin/GFAP-positive cells were mainly yellow (arrows). ^aP < 0.05, vs. ipsilateral limb-training; ^bP < 0.01, vs. untreated group. Data are expressed as mean ± SD (n = 8 rats per group per time point). One-way analysis of variance was used to compare differences between the groups.

Figure 5

Nestin/microtubule-associated protein-2 (MAP2)-positive cells in the unaffected hemisphere in middle cerebral artery occlusion rats following ipsilateral or bilateral limb-training. In the gross specimen, the white area represents the cerebral infarction area. Nestin-positive cells are stained green. MAP2-positive cells are stained red. In the cytoplasm the Nestin/MAP2-positive cells were mainly yellow (arrows). ^aP < 0.05, vs. ipsilateral limb-training; ^bP < 0.01, vs. untreated group. Data are expressed as mean ± SD (n = 8 rats per group per time point). One-way analysis of variance was used to compare differences between the groups.