Basic neuroscienceOptimising Golgi-Cox staining for use with perfusion-fixed brain tissue validated in the zQ175 mouse model of Huntington's disease

•A modified reliable Golgi-Cox method is described.•It is inexpensive and can be performed in any neuroscience lab.•Perfusion-fixation with 4% paraformaldehyde yields good results.•Pre-sectioning of perfusion-fixed brain tissue is neither required nor preferred for modified Golgi-Cox staining.•We demonstrate reliable changes in striatal dendritic morphology in the Q175 mouse model of Huntington's disease.

BackgroundThe Golgi-Cox stain is an established method for characterising neuron cell morphology. The method highlights neurite processes of stained cells allowing the complexity of dendritic branching to be measured.New methodsConventional rapid Golgi and Golgi-Cox methods all require fresh impregnation in unfixed brain blocks. Here, we describe a modified method that gives high quality staining on brain tissue blocks perfusion-fixed with 4% paraformaldehyde (PFA) and post-fixed by immersion for 24 h.ResultsTissue perfused with 4% PFA and post fixed for 24 h remained viable for the modified Golgi-Cox silver impregnation staining of mouse striatum from perfused wild type and zQ175. It was not found necessary to impregnate tissue blocks with Golgi solutions prior to sectioning, as post-sectioned tissues yielded equally good impregnation. Impregnation for 14 days resulted in optimal visualisation of striatal neuron and dendritic morphology. Although no modifications applied to the rapid Golgi method were reliable, the modified Golgi-Cox method yielded consistently reliable high-quality staining.Comparison with existing methodsThe current method used fixed tissues to reduce damage and preserve cell morphology. The revised method was found to be fast, reliable and cost effective without the need for expensive staining kits and could be performed in any neuroscience lab with limited specialist equipment.ConclusionsThe present study introduces a robust reproducible and inexpensive staining method for identifying neuronal morphological changes in the post fixed mouse brain, and is suitable for assessing changes in cell morphology in models of neurodegeneration and in response to experimental treatment.