Staining neurons with Golgi techniques in degenerative diseases of the brain

What is it about?

A detailed morphological study of neurons in healthy and pathological conditions requires reasonably a number of special techniques, which may visualize the majority of neurons in a thick three-dimensional arrangement. A detailed visualization of neurons must include the cell body, most of the dendritic arbor, the dendritic spines, the axon, the axonal collaterals and the synapses. An ideal morphological technique for the study of degeneration and regeneration processes of the central nervous system must also visualize clearly the long and short neuronal circuits, as well as the dendritic and axonal bands and tracks. It is also of substantial necessity that the histological techniques must enable the precise and accurate morphometric estimation of the dendritic spines, which is of great value for the study of aging, and the processes of neuronal degenerations and regeneration. The neuroscientist endeavors to study and follow precisely all the spatiotemporal morphological alterations, which occur during the various degenerative processes continuously, resulting in neuronal death and in serious degradation of the neuronal networks.

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Why is it important?

In the endeavor for a clear and accurate visualization of the sequential stages of the neuronal degeneration and death, silver impregnation techniques have played a prominent role for many years, enabling the study of degenerating axons, dendrites, spines, synaptic boutons and axonal terminals. Those techniques stain also the population of the reactive astrocytes, enabling the estimation of the neuronal, astrocytic ratio in degenerative conditions. In addition, silver techniques may also provide an insight in the pathogenesis of neurological disorders and clarify some of the mechanisms, which are involved in the remodeling of neuronal networks in the recovering brain, either on the basis of neuronal plasticity or under the possible therapeutic interventions. Thus, the modern versions of the techniques contribute substantially to the accumulation of valuable data, obtained from the detailed morphological analysis of the autopsy material in debilitating diseases, revealing ‘Dark’ neurons, dendritic alterations, neurofibrillary degeneration, neuritic plaques, microglial cell proliferation and alterations of the brain capillaries (Gallyas et al.,1993). They may be helpful in assessing and staging neurotoxicity and in understanding the role that the reactive astrocytes play in the degenerating processes. Whenever the neuroscientist applies these techniques may insert further in the pathways of neuronal disintegration, apoptosis and death, which may occur under various conditions and causative factors (Baloyannis, 2009). For many years, we have applied the semi rapid Golgi method in our laboratory (Baloyannis, 2015) in an attempt to study the morphological and morphometric alterations of dendrites and dendritic spines in dementias, including vascular dementia, Parkinson’s disease associated with dementia, frontal dementia, frontotemporal dementia and Alzheimer’s disease, at any stage.

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