Strain-dependent recovery of spontaneous hindlimb movement in spinal cord transected mice (CD1, C57BL/6, BALB/c).

Abstract

Reorganization and plasticity after spinal cord injury have been recently shown to take place in sublesional neuronal networks, but the possibility of strain-dependent changes at that level has never been explored. The authors studied the spontaneous return of hindlimb movement in low-thoracic spinal cord transected (Tx) mice from 3 commonly used strains. Without intervention, most CD1, C57BL/6, and BALB/c mice displayed some hindlimb movement recovery after Tx. Although all assessment methods unanimously reported that CD1 displayed higher recovery levels than did the C57BL/6 and BALB/c, higher scores were generally found with the Antri-Orsal-Barthe (M. Antri, D. Orsal, & J. Y. Barthe, 2002) and the Average Combined Score (P. A. Guertin, 2005a) methods. Such spontaneous recovery in low-thoracic Tx mice is likely the result of neuronal plasticity at the lumbosacral spinal cord level, suggesting that these sublesional changes are strain dependent.

Non-assisted treadmill training does not improve motor recovery and body composition in spinal cord-transected mice

“…[6][7][8] Here, Tx mice from the untrained group displayed hindlimb movements corresponding to AOB scores no greater than '1' (Figure 1a). Similar results were found in the trained mice.…”

“…1,2 In fact, even without pharmacological aids, regular TT assisted with a weight-supporting harness and/or tail or sexual organ pinching can enable the expression of involuntary 'reflex' stepping in low-thoracically spinal cord-transected (Tx) animals. [3][4][5] However, without assisted training, some spontaneously occurring small amplitude hindlimb movements were also shown to progressively occur a few weeks post-Tx in untrained Tx mice, [6][7][8] suggesting that basic spontaneous sublesional plasticity and spinal learning events may occur even in the absence of assisted training. Untrained Tx mice were also found to undergo significant changes in body compositionFfor example, body weight (À24%) and soleus fibre properties (À32% in mass and maximal force) within a few days postTx, 9 whereas assisted TT was found to partially prevent muscular property changes in Tx cats and rats.…”

“…In this study, we determined to examine the effect of TT alone (without assistance) on locomotor recovery. This experimental protocol was driven by the idea that progressively occurring motor and locomotor-like movements displayed typically in untrained Tx animals, [6][7][8] if combined with the stimulation provided by the moving treadmill belt, may suffice to further promote locomotor function recovery. However, as shown here, non-assisted TT did not enable the , respectively.…”

“…5 We also used a semiquantitative assay called Average Combined Score (ACOS) that has been developed in our laboratory for 'live' semiquantitative assessment of hindlimb movements in Tx rodents. [6][7][8] ACOS is designed to assess non-locomotor movements (NLM, number min À1 ), locomotor-like movements (LM, number min…”

Synergistic Effects of D1/5 and 5-HT1A/7 Receptor Agonists on Locomotor Movement Induction in Complete Spinal Cord–Transected Mice

“…Preoperative care included injections 30 min prior to surgery of lactate-Ringer solution (1.0 ml, administered subcutaneously [sc]), an antibiotic (Baytril; 5 mg/kg, sc; Bayer, Toronto, Ontario), and an analgesic (buprenorphine; 0.1 mg/kg, sc; ScheringPlough, Pointe-Claire, Quebec). The surgery was performed under general anesthesia with isoflurane (2.5%) as described elsewhere (Guertin 2005;Lapointe et al 2006;Ung et al 2007). Briefly, a nonlaminectomy complete spinal cord transection (Tx) was performed using microscissors inserted between the ninth and tenth thoracic vertebrae.…”