Neurite-like processes

In HeLa cells, the striking morphological alterations which follow exposure of the cells to butyrate are characterized by the extension of neurite-like processes (Fig. 1). No significant differences in the fine structure of the ceil surface was observed by scanning electron micrography (Fig. 1). In addition to butyrate, propionate and pentanoate but not other homologous... 

The formation of the neurite-like processes appears to be dependent on assembly of microtubules as colchicine and Colcemid, antimicrotubule drugs, prevented shape changes in the presence of butyrate (2,8). The amount of tubulin per cell did not change when HeLa were treated with butyrate (R.C.Henneberry, unpublished observations). The role of microtubule assembly was further explored with a calcium ionophore which alters intracellular calcium levels and thus promotes microtubule depolymerization. 

Morphological changes were prevented in butyrate-treated HeLa cells by actinomycin D and cycloheximide (2,8,13). After removal of butyrate, the cells reverted to a normal morphology over a 24 h time course (2,8,12,13). When butyrate-treated cells were detached from the cuTture dishes with trypsin, they assumed a spherical shape and, when replated in the absence of butyrate, their neurite-like processes transiently re-extended (13). This re-extension was blocked when cycloheximide but not the calcium ionophore was included during the initial exposure of the cells to butyrate (13). Process formation, however, did resume in the presence of cycloheximide (1 3). These results were interpreted as indicating that the fatty acid induces a protein(s) required for process formation which can accumulate in the absence of processing and promote processing in the absence of inducer (13). 

Carmona, A., Cloetens, P., Deves, G., Bohic, S., Ortega, R. (2008) Nano-imaging of trace metals by synchrotron X-ray fluorescence into dopaminergic single cells and neurite-like processes. / Anal At Spectrom, 23, 1083-1088. 

Li, W. W.. and Casida, J. E. (1998). Organopho.sphoru.s neuropathy target esterase inhibitors selectively block outgrowth of neurite-like and cell processes in cultured cells. To.r.iail. Leu. 98, 139-146-... 

Alzheimer s disease (AD) is one of the most common forms of dementia that affect the elderly population. The histopathological hallmarks of AD are extracellular deposits known as neuritic amyloid plaques and intraneuronal inclusions composed of hyperphosphorylated tangles enriched with tau proteins.1 The principal component of the neuritic plaques is aggregation of amyloid (A0), which is likely to play a role in the neurodegenerative process. The relative contribution of the various forms (soluble dimers, small oligomers, protofibrils, and fibrils) of A0 to neuronal... 

In cestodes, most, perhaps all, of the neural elements are found in the ganglia of the scolex and the main nerve tracts. In these, the cell bodies are arranged peripherally around a core made up of a tangled mass of neuronal processes often referred to as neurites because it is impossible to distinguish between axons and dendrites. This mass constitutes the so-called neuropile . Like all differentiated cells in cestodes - and probably in all invertebrates - nerve cells are incapable of mitosis and hence new nerve cells must arise directly from the germinative ( = stem) cells (276). In D. dendriticum, the neuropile is composed of a dense network of unmyelinated nerve fibres with no extracellular stroma between the fibres (277). The fibres differ mainly in the content of different types of vesicles, which can be dense-core, small clear or large clear vesicles. The structure of synapses is discussed further on pp. 25—7. 

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