Muscle hypertonia after permanent focal cerebral ischemia in rats: a qualitative and quantitative behavioral and electrophysiological study

Abstract

Objectives: To examine the level of peripheral muscle resistance after cerebral ischemia. Methods: A total of 326 healthy male Sprague-Dawley rats were used in the present experiments. We used a modified method to establish peripheral muscle resistance in rat model of stroke, and qualified the recovery of motor functional deficits by behavioral measures and quantified the level of peripheral muscle resistance by electrophysiological test. Results: Neurological score started to go up from day 0, achieved its peak on day 3 (1.49 ± 0.56) and kept at a high level within 10 days after surgery. Compared with 1 day before surgery, both the turn score in corner test and asymmetry score in cylinder test were increased significantly on day 3, day 6 and day 9 after surgery (p < 0.01). On day 6 and day 9 after surgery, the Hmax:Mmax ratio of hemiplegic side of middle cerebral artery occlusion (MCAO) rats was obviously higher than the same side in healthy rat (p < 0.01) and the ratio on the contralateral side of MCAO rats (p < 0.05). Conclusions: There is a progressive increase in peripheral muscle resistance on day 6 to day 9 after surgery in a rat model of postischemic stroke.

KEYWORDS: :

• cerebral ischemia
• muscle resistance
• behavioral assessment
• electrophysiology