[Effects of tanycytes transplantation on the motor function score and rubrospinal motor evoked potentials of adult rats after spinal cord completely transected].

OBJECTIVE: To determine whether tanycytes be able to support the regeneration of completely transected spinal cord in adult rats. METHODS: Subcultured tanycytes was transplanted into completely T8 transected spinal cord using the untranslated completely transected rats as control. After transplantation the rubrospinal motor evoked potentials were recorded below the injury level at the end of 12th week, assistant by Basso-Beatie-Bresnahan locomotor rating scale and histology method. RESULTS: At the end of 12th week the total peak amplitude of rubrospinal motor evoked potentials (MD = 133.2 microV, P < 0.01) and BBB locomotor rating scale (MD = 5.0000, P < 0.01) were both significantly improved in cell transplanted group compared with that in the untranslated control group, while the latency of the first peak was shortened (MD = 0.061 ms, P = 0.040). HE staining showed more integrity in transected spinal cords in cells transplanted groups. CONCLUSION: Transplanted tanycytes can support the regeneration of transected spinal cords in rats.

[Relationship between graded spinal cord injury and rubrospinal MEPs in rats].

AIM: To explore an accurate neurophysiological technique that demonstrates small functional differences after spinal cord injury and assesses therapeutic interventions. METHODS: A modified weight drop (WD) technique was used at T8 in rats to build graded spinal cord injury model. Rubrospinal MEPs were recorded at T13 epidurally to monitor spinal cord function in end week 4 after graded spinal cord injury. The efficacy of this techniques to monitor spinal cord function was compared to BBB locomotor rating scale and histologic evaluation. RESULTS: A characteristic peak complex of rubrospinal MEPs in sham-operated group consisted of 5-7 positive waves and 4-5 negative waves emerging after red nucleus stimulation. The summed peak to peak amplitude (for practical reasons, called peak amplitude) was (195.25 +/- 34.35) microV and decreased following spinal cord injury. The latency of the first peak (positive wave) was (1.57 +/- 0.15) ms and prolonged following spinal cord injury. Significant Linear relationship existed between the peak amplitude and the BBB scores (r = 0.79) and between the peak amplitude and the residual matter obtained from the section with maximum tissue damage( r = 0.87). The close relationship between the latency of the first peak and the BBB scores (r = -0.88) and between the latency of the first peak and residual matter (r = -0.86) were observed. CONCLUSION: Amplitudes and latencies of rubrospinal MEPs are very valuable parameters to demonstrate small function differences. Rubrospinal MEPs can be used as a reliable measure for motor function prognosis after spinal cord injury.

[Excitatory postsynaptic potential evoked by stimulation of the ventrolateral region of the cerebellum in crucian carp Mauthner cell].

In the present experiments, the characteristics of the electrical responses to stimulation of the cerebellum in crucian carp Mauthner cell were explored with microeletrode intracellular recording technique. A composite excitatory postsynaptic potential (cerebellum-evoked EPSP) could be induced from the soma, the ventral dendrite and the proximal end of the lateral dendrite in crucian carp Mauthner cell (M-cell) on either side by stimulation of the ventrolateral region of the cerebellum. The cerebellum-evoked EPSP presented characteristics of relatively short latency (0.63+/-0.09 ms), longer duration (5.49+/-1.13 ms), graded amplitude and dependence on stimulation frequency. Stimulation of the cerebellum with higher intensity always activated the M-cell orthodromically. Multiple intracellular recordings showed that the cerebellum-evoked EPSP originated in the distal end of the ventral dendrite. The results suggest that the cerebellum-M-cell pathway is probably composed of a group of neuron chains with different numbers of synaptic relays projecting to the distal end of the ventral dendrite in order of length of the chains.