[Effects of Limb Ischemic Postconditioning on Behavioral Improvement and Proliferation of Neural Cells in Rats with Transient Cerebral Ischemia]

Abstract

Objectives: To determine the effects of non-invasive limb ischemic postconditioning (NLIP) on the behavioral performance and the expression and distribution of neural cells in rats with ischemic cortex.

Methods: Rats were randomly divided into 3 groups: sham group (n=10), ischemia/reperfusion (I/R) group (n=50), and NLIP group (n=50). Focal cerebral ischemia was induced by intraluminal MCAO in the rats in the I/R and NLIP groups, while no suture was inserted in the sham-operated rats. NLIP (reperfusion-10 min, ischemia-10 min, ×3 cycles) was conducted immediately after reperfusion on bilateral femoral arteries by modified ischemicelastic bands. Body mass and behavioral performance of the rats were assessed at 3 d, 7 d, 14 d, 21 d and 28 d post-ischemia (n=5-10). Doublecortin (DCX) and glial fibrillary acidic protein (GFAP) in the ischemic cortex were detected by immunohistochemistry.The expression of microtubule associated protein 2 (MAP2) was detected by Western blot.

Results: The rats in the sham group showed mild body mass loss and minor neurological deficit 1-3 d post-ischemia and weakened muscle strength 1 d post-ischemia, which were alleviated gradually overtime. Compared with the sham group, neurological deficits were more obvious in the rats in the I/R and NLIP groups, which were alleviated 3-21 d post-ischemia and reached a level close to that of the sham group at 28 d post-ischemia. No significant difference was found betweenthe I/R and NLIP groups in neurologic deficit scores.NLIP significantly alleviated body mass loss 2-7 d post-ischemia (P<0.05) and improved muscle strength 14-28 d post-ischemia (P<0.05).Compared with the sham group, rats in the I/R and NLP groups had increased numbers of DCX and GFAP-labeled cells in the ischemic penumbra over time, increased hypotrophic cell bodies and longer and thickened dendrites, and decreased expression of MAP2 (P>0.05) at 3 d post-ischemia prior to an up-regulation.Higher expression of MAP2 was found 14-21 d post-ischemia (P<0.05) in the I/R group and 7-28 d post-ischemia in the NLIP group(P<0.05). Significant difference in MAP2 was found between the I/R and NLIP groups at 7 d post-ischemia (P<0.05).

Conclusions: NLIP has the potential to improve neurological outcomes and promote increase of neural cells in penumbral cortex after cerebral ischemia.

Keywords: Astrocytes; Cerebral ishcemia; Ischemic postconditioning; Neurons; Neuroprotection.