Neurofilament phosphorylation in neuronal perikarya following axotomy: A study of rat spinal cord with ventral and dorsal root transection

Abstract

Rat spinal cord was stained by indirect immunofluorescence with 11 neurofilament monoclonal antibodies that recognize phosphorylated epitopes. All monoclonals were axon-specific in this location. The large motoneurons containing bundles of neurofilaments did not stain and the pattern remained unchanged after transection of the sciatic nerve in the thigh. With nine monoclonals, stained motoneurons were observed in the ventral horns 3 days, 5 days, 1 week, and 2 weeks after transection of the ventral roots close to the spinal cord. The abnormal motoneurons were typically scattered among normal (i.e., nonstained) cells. Even in animals showing the most severe reaction, the whole motoneuron population at the site of rhizotomy was not affected, stained and nonstained perikarya often coexisting side by side. Stained motoneurons were no longer observed 3 weeks after ventral root transection. Changes in neuronal immunoreactivity were also observed after dorsal root transection. However, a different population was affected, i.e., middle-sized neurons in dorsal horns and at the base of ventral horns. With two monoclonals (A9 and D21), cell bodies remained negative following all operations. It is concluded that axotomy in proximity of the cell body may induce certain neurofilament phosphorylation events in motor neuron perikarya, whereas other phosphorylation events remain confined to the axons under these experimental conditions. The absence of changes after transection of the sciatic nerve in the thigh suggests that neurofilament phosphorylation is a reaction to cell injury rather than a cellular event related to nerve regeneration.

Peripheral axotomy slows motoneuron degeneration in a transgenic mouse line expressing mutant SOD1 G93A

“…Although it was suggested that accumulation of NFs in the cell bodies in the NF-H-overexpressing mice and NF-L knockout mice may play a role in extending motoneuron survival, possibly by an increased Ca ϩϩ buffering capacity (Couilard-Despres et al, 1998;Williamson et al, 1998), the accumulation of neurofilaments is not shared in the axotomized motoneurons. Axotomy in ventral root close to the spinal cord is known to induce an acute response that includes chromatolysis and an increase in phosphorylated NFs in neuronal cell bodies (Goldstein et al, 1987;Mansour et al, 1989). However, these changes are unlikely to play a central role in the current experimental paradigm.…”

Developmental expression of the actin depolymerizing factor ADF in the mouse inner ear and spiral ganglia

“…The antibody shows no immunoreactivity with dephosphorylated neurofilaments or with other intermediate filament proteins (manufacturer's technical information). In immunohistochemistry the antibody stained neurofilament-rich structures with an identical pattern of immunoreactivity when compared to other antibodies directed against neurofilament 200 (Mansour et al, 1989). The antibody is frequently used in immunohistochemical analyses (Peichl and Gonzalez-Soriano, 1993;Paysan et al, 2000;Leclere et al, 2007).…”

Altered Expression of Cytoskeletal and Axonal Proteins in Oxaliplatin-Induced Neuropathy

“…Conversely, on day 28, a significant increase in the protein level of pNfH was observed in the SC and cortex areas. Although the highly pNfH isoform of the neurofilament subunits is present only in mature axons in the majority of adult neurons [22] , it has been shown that after axonal damage certain cells have an abnormal distribution of pNfH in the soma and dendrites [23] . It has been shown that increased somatic Nf phosphorylation occurs in systems where neurons regenerate successfully [24] .…”