Development of an Intervertebral Disc Degeneration Model using Newzealand White Rabbits

STUDY DESIGN: An experimental animal study. OBJECTIVES: To create a more appropriate disc degeneration model which shows how Interleukin 1alpha may induce the activation of metalloproteinases within the nucleus pulposus. SUMMARY OF LITERATURE REVIEW: There are few disc degeneration models wherein there is activation of metalloproteinases within the nucleus pulposus without structural destruction of the intervertebral disc. MATERIALS AND METHODS: Three consecutive intervertebral discs in New Zealand White Rabbits were exposed. Each disc was injected with 0.1ml of saline (Saline group), 0.1ml of 1microg/ml (IL-1 group), 0.1ml of 10microg/ml (IL-10 group) of IL-1alpha through a 30-gauge needle. The lumbar spine was harvested 12 weeks after operation. We then analyzed radiographic findings and histological changes. RESULTS: There was no difference in the radiological disc height index among the three groups; 0.071 in saline group, 0.045 in IL-1 group and 0.058 in IL-10 group (p=0.194). The histological cellularity of the nucleus pulposus revealed a decrease in the number of cells (p=0.0001, 1.42 in saline group vs. 3.00 in IL-10 group; p=0.001, 2.00 in IL-1 group and 3.00 in IL-10). The histological matrix of the nucleus pulposus was 1.42 in saline group and 2.42 in IL-10(p=0.007), which meant that there had been condensation of the extracellular nucleus pulposus matrix. CONCLUSIONS: The results of this study demonstrate that interleukin-1alpha may contribute to degradation of the nucleus pulposus. This is useful for future study into the effects of the cytokine inhibitor on matrix regeneration and cellularity in the nucleus pulposus in intervertebral disc disease.

Characteristics of Light-evoked Retinal Ganglion Cell Activity with Postnatal Maturation in SD Rat / 의학물리

As part of Korean retinal prosthesis project, we have provided preliminary experimental results regarding voltage parameters for the stimulation of chemically degenerated rabbit retina. Since our APB-treated chemically degenerated retina is only ON-pathway blocked, now we switch our experiments to more appropriate retinal degeneration model, genetically degenerated retina model (RD mouse: rd/rd (C3H/HeJ)). Before studying with RD mouse, we started control experiments with normal SD rat to understand characteristics of retinal ganglion cell activity with postnatal maturation in rodents. Ganglion cell activities were recorded with 8x8 multi-electrode array. Moving spontaneous bursts appeared until postnatal day of 15. During pre-eye opening period, no light evoked response appeared. After postnatal day of 2 weeks (post-eye opening period), ON-, OFF- and ON/OFF response appeared. The fractional distributions of ON, OFF, and ON/OFF ganglion cell is about 40%, 50%, and 5%. The percentage (%) of light evoked response in each dorso-temporal, ventral, and dorso-nasal area of eye is about 50%, 37.5% and 12.5%, respectively. We concluded that the optimal period for experiment in rodent is about postnatal day of 2~3 weeks.