PMID: 7536819Apr 1, 1995Paper

Increased collateral sprouting of primary afferents in the myelin-free spinal cord

The Journal of Neuroscience : the Official Journal of the Society for Neuroscience
G SchweglerJ P Kapfhammer

Abstract

After partial lesions, uninjured nerve fibers have been shown to sprout and expand their connections within the CNS of adult mammals. The extent of this anatomical plasticity in adults is rather limited in comparison to embryonic or neonatal animals. Factors that might limit sprouting of nerve fibers and suppress anatomical plasticity in the CNS include myelin-associated neurite growth inhibitory molecules present in the CNS of adult mammals. To examine further the role of these neurite growth inhibitors, we have studied the ability of primary afferent fibers to sprout in the absence of myelin within a partially deafferented spinal cord. Myelination was suppressed in the lower thoracic and lumbar spinal cord of rats using neonatal x-irradiation. Dorsal roots of lumbar segments L2-L4 were cut in myelin-free and normal spinal cords of 8- or 15-d-old rats. Sprouting of primary afferents was measured after 20 d using thiamine monophosphatase (TMP) histochemistry. TMP is a specific marker enzyme for small-diameter primary afferents that terminate in the substantia gelatinosa (lamina II) of the spinal cord. When compared to the control groups, collateral sprouting of TMP-positive afferents was significantly enhanced in the myelin-fre...Continue Reading

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