Changes in forelimb-hindlimb coordination after partial spinal lesions of different extent in the rat.

Forelimb-hindlimb coordination in adult rats moving freely along 2m long runway was investigated using the method of footprint recording. Rats were divided into 3 groups with different extent of spinal lesions (T(9)). Before surgery rats moved with a mean locomotor speed of 73±20 to 96±18cms(-1), stride lengths of 17.

Time-related changes of motor unit properties in the rat medial gastrocnemius muscle after the spinal cord injury. II. Effects of a spinal cord hemisection.

The contractile properties of motor units (MUs) were investigated in the medial gastrocnemius (MG) muscle in rats after the spinal cord hemisection at a low thoracic level. Hemisected animals were divided into 4 groups: 14, 30, 90 and 180 days after injury. Intact rats formed a control group.

Time-related changes of motor unit properties in the rat medial gastrocnemius muscle after spinal cord injury. I. Effects of total spinal cord transection.

The contractile properties of motor units (MUs) were electrophysiologically investigated in the medial gastrocnemius (MG) muscle in 17 Wistar three-month-old female rats: 14, 30, 90 and 180 days after the total transection of the thoracic spinal cord and compared to those in intact (control) rats. A sag phenomenon, regularly observed in unfused tetani of fast units in intact animals at 40 Hz stimulation, almost completely disappeared in spinal rats. Therefore, the MUs of intact and spinal rats were classified as fast or slow types basing on 20 Hz tetanus index, the value of which was lower or equal 2.

Recovery of overground locomotion following partial spinal lesions of different extent in the rat.

In six rats with incomplete low thoracic spinal cord lesions of different extent, basic gait indices such as locomotor speed, step cycle duration, soleus (Sol) muscle activity duration, the interval between the onsets of Sol and tibialis anterior (TA) muscle activities and interlimb coordination were investigated by EMG analysis of the Sol and TA muscles recorded using chronic electrodes. The operated animals were divided into two subgroups: (1) those with a smaller lesion involving the dorsal quadrants of the spinal cord and, to a variable extent, the ventrolateral funiculi, and (2) those with an extensive lesion sparing only parts of the ventral funiculi. The locomotion of all rats was tested once a week for the first 5 weeks postsurgery and then once or twice a month, up to 3.

Overground locomotion after incomplete spinal lesions in the rat: quantitative gait analysis.

In rats with incomplete low thoracic spinal cord lesions of different extents, the basic indices of gait such as locomotor velocity, step and stance phase duration and the duty factor (i.e., the relative duration of the stance phase) during overground runway locomotion were analyzed using contact electrodes on each paw for data recording.

Comparison of two methods for quantitative assessment of unrestrained locomotion in the rat.

Changes in locomotor movements induced by central and peripheral nerve injury or obtained as a result of pharmacological treatment are increasingly being investigated in rats. Several methods have been used to assess changes in the main locomotor indices, most of which are based on video recordings, usually with low time resolution, or on X-ray cinematographic recordings. Other methods are based on qualitative visual locomotor scoring systems like the BBB scale.

Intrathecal administration of yohimbine impairs locomotion in intact rats.

The effects of upper lumbar level intrathecal injection of yohimbine, an alpha2-noradrenergic antagonist, on overground locomotion in intact rats was studied. This treatment caused dose-dependent impairment of hindlimb locomotor movement, which varied from transient hindlimb paralysis at a dose of 200 microg/20 microl to transient trunk instability at 50 microg/20 microl. Repetitive (every 48 h) injections of yohimbine at high (200 microg/20 microl) and medium (100 microg/20 microl) doses caused tachyphylaxis, which usually led to a lack of reaction to the third injection.

Changes in contractile properties of motor units of the rat medial gastrocnemius muscle after spinal cord transection.

The effects of complete transection of the spinal cord at the level of Th9/10 on contractile properties of the motor units (MUs) in the rat medial gastrocnemius (MG) muscle were investigated. Our results indicate that 1 month after injury the contraction time (time-to-peak) and half-relaxation time were prolonged and the maximal tetanic force in most of the MUs in the MG muscle of spinal rats was reduced. The resistance to fatigue also decreased in most of the MUs in the MG of spinal animals.

Intrathecal application of cyproheptadine impairs locomotion in intact rats.

In intact adult rats, cyproheptadine, a 5-HT2 antagonist, administered intrathecally at the midlumbar segments was found to impair hindlimb locomotor movements during overground locomotion. These effects were dose-dependent; they varied from transient complete hindlimb paraplegia seen at doses of 300 microg/20 microl, to short-lasting trunk instability at doses of 100 microg/20 microl. After the return of overground locomotion, transient abduction of one of the hindlimbs was observed in some animals.