Experimental neurology
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Axonal regeneration can be influenced by a conditioning lesion (an axonal injury made prior to a second test lesion). Previously, sympathetic neurons in vivo were shown to respond to a conditioning lesion with decreased neurite outgrowth, in contrast to the enhanced outgrowth observed in all other peripheral neurons examined. The present experiments tested the effects of a conditioning lesion on neurite outgrowth in vitro from the superior cervical ganglion (SCG) and the impact of several factors on that response. ⋯ Deletion of the gene for leukemia inhibitory factor (LIF), a gene induced by axotomy, did not abolish the conditioning lesion effect in SCG explants or dissociated cell cultures. In conclusion, sympathetic neurons are capable of responding to a conditioning lesion with increased neurite outgrowth. The hypothesis that the neuronal cell body response to axotomy plays an important role in the conditioning lesion response is discussed.
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Experimental neurology · Jul 2005
A noninvasive ultrasonographic method to evaluate bladder function recovery in spinal cord injured rats.
Suprasacral spinal cord injury induces changes in the mechanical and neuronal properties of the bladder resulting in bladder areflexia followed by bladder-sphincter dyssynergia and detrusor muscle hypertrophy, which lead to urinary retention and increased bladder size. These changes are most often quantified using highly skilled urodynamic techniques that involve catheterization. We investigated whether a hand-held digital ultrasound imaging system could monitor urinary retention in the bladder following spinal cord injury in adult rats. ⋯ Post hoc analysis indicated that the degree of bladder function recovery recorded at the end of the study correlated with the degree of bladder function recovery recorded at 6 days post-injury, indicating that bladder function recovery can be predicted by analyzing bladder volume as early as 6 days post-injury. Bladder function recovery correlated with locomotor recovery as assessed using the BBB locomotor rating scale. While providing a noninvasive assessment of bladder function with no detrimental impact on locomotor function or assessment, this protocol provides researchers with a clinically relevant outcome measure for quantifying bladder function recovery after spinal cord injury or after experimental treatments for spinal cord injury.
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Experimental neurology · Jul 2005
Intrathecal injection of GDNF and BDNF induces immediate early gene expression in rat spinal dorsal horn.
Glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) are potent trophic factors for dorsal root ganglion cells. In addition, these factors are produced in subsets of dorsal root ganglion cells and transported anterogradely to their terminals in the superficial dorsal horn of the spinal cord, where they constitute the only source of GDNF and BDNF. We investigated the effect of 10 mug GDNF and BDNF injected by lumbar puncture on the expression of the immediate early gene (IEG) products c-Fos, c-Jun, and Krox-24 in the adult rat dorsal horn. ⋯ Additionally, using double-labeling immunofluorescence combined with confocal microscopy, it was found that after intrathecal GDNF injection 35% of c-Fos-labeled cells were also labeled for RET. These results demonstrate that intrathecally administered GDNF and BDNF induce IEG expression in dorsal horn neurons in the adult rat, supposedly by way of their cognate receptors, which are present on these neurons. We further suggest that the endogenous release of GDNF and BDNF, triggered by nociceptive stimuli, is involved in the induction of changes in spinal nociceptive transmission as in various pain states.
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Experimental neurology · Jul 2005
Quantitative assessment of forelimb motor function after cervical spinal cord injury in rats: relationship to the corticospinal tract.
Approximately 50% of human spinal cord injuries (SCI) are at the cervical level, resulting in impairments in motor function of the upper extremity. Even modest recovery of upper extremity function could have an enormous impact on quality of life for quadriplegics. Thus, there is a critical need to develop experimental models for cervical SCI and techniques to assess deficits and recovery of forelimb motor function. ⋯ Assessment of rope climbing ability revealed permanent impairments in forelimb use and deficits in hindlimb use and trunk stability. Sensory testing using a dynamic plantar aesthesiometer revealed that there was no increase in touch sensitivity in the affected forelimb. For the cases in which both histological and behavioral data were available, spared forelimb motor function was greatest in rats in which there was sparing of the dorsal CST.
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Experimental neurology · Jun 2005
Comparative Study Clinical TrialThe beneficial effects of subthalamic nucleus stimulation on manipulative finger force control in Parkinson's disease.
We investigated the differential effects of levodopa medication and STN stimulation on finger force control in Parkinson subjects grasping to lift an object and performing vertical point-to-point movements of a hand-held object. The experiments were conducted in four treatment conditions: off-drug/off-stimulation, off-drug/on-stimulation, on-drug/off-stimulation and on-drug/on-stimulation. We found that the bradykinesia in Parkinsonian subjects improved by both levodopa medication and STN stimulation. ⋯ Despite some similarities regarding therapeutic effects on bradykinesia, our findings contrast with earlier observations with respect to the differential effects of levodopa and STN stimulation on the scaling of fingertip forces in Parkinson's disease. While levodopa causes an overshoot of fingertip forces, STN stimulation appears to be sufficient to alleviate, but not normalise the force excess. STN stimulation enables Parkinson subjects to scale grip force more accurately to the loads arising from voluntary manipulation of hand-held objects.