Effect of lesion proximity on the regenerative response of long descending propriospinal neurons after spinal transection injury.

Background: The spinal cord is limited in its capacity to repair after damage caused by injury or disease. However, propriospinal (PS) neurons in the spinal cord have demonstrated a propensity for axonal regeneration after spinal cord injury. They can regrow and extend axonal projections to re-establish connections across a spinal lesion.

Chondroitinase treatment following spinal contusion injury increases migration of oligodendrocyte progenitor cells.

Following spinal cord injury (SCI), the demyelination of spared intact axons near the lesion site likely contributes to the loss of motor function. This demyelination occurs when oligodendrocytes, the myelinating cells of the central nervous system (CNS), are either destroyed during the initial trauma or die as a result of secondary pathology. In an attempt to remyelinate the affected axons, endogenous oligodendrocyte progenitor cells (OPCs) begin to accumulate at the border of demyelination.

Long descending cervical propriospinal neurons differ from thoracic propriospinal neurons in response to low thoracic spinal injury.

Background: Propriospinal neurons, with axonal projections intrinsic to the spinal cord, have shown a greater regenerative response than supraspinal neurons after axotomy due to spinal cord injury (SCI). Our previous work focused on the response of axotomized short thoracic propriospinal (TPS) neurons following a low thoracic SCI (T9 spinal transection or moderate spinal contusion injury) in the rat. The present investigation analyzes the intrinsic response of cervical propriospinal neurons having long descending axons which project into the lumbosacral enlargement, long descending propriospinal tract (LDPT) axons.

Intrinsic response of thoracic propriospinal neurons to axotomy.

Background: Central nervous system axons lack a robust regenerative response following spinal cord injury (SCI) and regeneration is usually abortive. Supraspinal pathways, which are the most commonly studied for their regenerative potential, demonstrate a limited regenerative ability. On the other hand, propriospinal (PS) neurons, with axons intrinsic to the spinal cord, have shown a greater regenerative response than their supraspinal counterparts, but remain relatively understudied in regards to spinal cord injury.

Lack of axonal sprouting of spared propriospinal fibers caudal to spinal contusion injury is attributed to chronic axonopathy.

We have previously shown that a small percentage of long descending propriospinal tract (LDPT) axons are spared, whereas few short thoracic propriospinal (TPS) fibers survive 2 weeks following severe (50 mm weight drop) low thoracic spinal cord contusion injury (SCI). Here, we extended those findings to a moderate (25 mm weight drop) T9 SCI and assessed the effects of this lesion severity on propriospinal tract fibers at different time periods after injury. We anterogradely labeled fibers with fluororuby (FR) or WGA-HRP to determine their location and number 2, 4, 6, and 16 weeks post-SCI.

Cauda equina repair in the rat: part 1. Stimulus-evoked EMG for identifying spinal nerves innervating intrinsic tail muscles.

Cauda equina injuries may produce severe leg and pelvic floor dysfunction, for which no effective treatments exist. We are developing a rat cauda equina injury model to allow nerve root identification and surgical repair. One possible difficulty in implementing any repair strategy after trauma in humans involves the correct identification of proximal and distal ends of nerve roots separated by the injury.

Evaluation of olfactory ensheathing and schwann cells after implantation into a dorsal injury of adult rat spinal cord.

Olfactory ensheathing cells (OECs) and Schwann cells (SCs) obtained from adult transgenic rats expressing alkaline phosphatase (AP) were studied following implantation into intact spinal cord and after dorsal column crush (DCC) injury, either within the lesion or near the lesion borders. We observed no evidence of migration of AP OECs or AP SCs after lesion site injections, with most cells remaining in or nearby the injection/lesion site. Acute injection of either cell type outside of the lesion site resulted in the presence of cells in the lesion even two hours after injection.

Modification of the regenerative response of dorsal column axons by olfactory ensheathing cells or peripheral axotomy in adult rat.

The regeneration of sciatic-dorsal column (DC) axons following DC crush injury and treatment with olfactory ensheathing cells (OECs) and/or sciatic axotomy ("conditioning lesion") was evaluated. Sciatic-DC axons were examined with a transganglionic tracer, cholera toxin conjugated to horseradish peroxidase, and evaluated at chronic time points, 2-26 weeks post-lesion. With DC injury alone (n = 7), sciatic-DC axons were localized to the caudal border of the lesion terminating in reactive end bulbs with no indication of growth into the lesion.

Differential vulnerability of propriospinal tract neurons to spinal cord contusion injury.

The propriospinal system is important in mediating reflex control and in coordination during locomotion. Propriospinal neurons (PNs) present varied patterns of projections with ascending and/or descending fibers. Following spinal cord contusion injury (SCI) in the rat, certain supraspinal pathways, such as the corticospinal tract, appear to be completely abolished, whereas others, such as the rubrospinal and vestibuospinal tracts, are only partially damaged.

Large-scale plasticity in barrel cortex following repeated whisker trimming in young adult hamsters.

Using the 2DG/immunostaining method [McCasland, J.S., Graczyk, G.