Understanding the Brain

Fluoro-Jade stain

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Fluoro-Jade stain is a fluorochrome derived from fluorescein, and is commonly used in neuroscience disciplines to label degenerating neurons in ex vivo tissue of the central nervous system. The first fluoro-jade derivative was reported by Larry Schmued in 1997 as an alternative method from traditional methods for labeling degenerating neurons such as silver degeneration stains, H&E stain, or Nissl stain.[1] Fluoro-Jade may be preferred to other degenerative stains due to simplicity of staining procedures and visual interpretation, which are common drawbacks of conventional degenerative stains. However, the mechanism by which fluoro-jade labels degenerating neurons is unknown thus creating some controversy to the actual physiological condition of the labeled cells.

File:KA fljb.jpg
Fluoro-Jade B positive neurons in the rat cortex after injection of kainic acid

Chemical properties

Currently, there are three fluoro-jade dyes (Fluoro-Jade,[1] Fluoro-Jade B,[2] and Fluoro-Jade C [3]), all of which are anionic tribasic derivatives of fluorescein and highly acidic.[3] All three fluoro-jade species have similar excitation and emission profiles as fluorescein (excitation: 495 nm; emission:521 nm) and thus can be visualized using a fluorescein/FITC filter. The newer dyes, fluoro-jade B and fluoro-jade C, were developed to improve signal to noise ratio, therefore creating superior compounds for visualizing finer neuronal morphology including dendrites, axons and nerve terminals.

General staining techniques

Nearly all processed tissue is compatible with fluoro-jade stain including tissue from rodents (mice and rats), nonhuman primates and humans. Mounted tissue is stepwise rehydrated with decreasing concentrations of alcohol. Potassium permanganate may be used to decrease background staining and protect tissue from fading and photo bleaching. Fluoro-Jade is highly soluble in water and is therefore first dissolved in distilled water. In order to be specific for degenerating neurons, fluoro-jade must be used in an acidic environment, therefore fluoro-jade is further diluted in glacial acetic acid. Additional water washes should be used to rinse tissue before drying and coverslipping.[1]

Fluoro-Jade staining procedures are flexible and therefore can be adapted to be compatible with other staining techniques such as immunohistochemistry. Several modifications to the general procedures can be made such as reducing potassium permanganate incubations to avoid disrupting immunofluorescent labeling. Background can be decreased by alternative methods such as lowering staining temperature or decreasing Fluoro-Jade concentration, which may be more compatible with other labeling techniques.[1] Such alterations, however should be determined empirically to optimize specific experimental conditions .

In addition to staining tissue from treated subjects, positive and negative controls should be included to ensure method specificity and validity. Typically tissue from untreated control subjects is included to show specificity for degenerating neurons as fluoro-jade should not stain non-degenerating tissue. Additionally, a positive control is included to ensure validity of staining procedures; to show that degenerating neurons will be stained with fluoro-jade. An acceptable positive control includes neurodegenerative tissue from subjects where fluoro-jade has already been validated, such as kainic acid treated animals.

Analysis

Fluoro-Jade stained tissue can be visualized under an epifluorescent microscope using a filter system designed for fluorescein or fluorescein isothiocynate (FITC) (excitation: 495 nm; emission:521 nm). Multiple morphological features can be detected using fluoro-jade stain including cell bodies, dendrites, axons, and axon terminals.[1] Even though all fluoro-jade derivatives can detect these specific morphological features, the newer derivatives (FlJb and FlJc) have greater specificity and resolution and therefore are superior in detecting finer morphological features.[3] Fluorojade is typically quantified in every 6th-12th 40 nm section within the region of interest and expressed as cells/section. Alternatively, stereological procedures may be used to estimate total fluorojade positive cells within the defined region.

Technique validation

As the mechanism of fluoro-jade labeling is unknown, correlative analysis with traditional neuronal degeneration stains was used to validate this technique. Initially fluoro-jade staining was compared with H & E and de Olmos’ cupric-staining methodologies in a variety of neurotoxic models of neurodegeneration such as injection of kainic acid, MPTP, or multivalent metals. Each of these neurotoxic insults produce brain-region specific neuronal degeneration and thus could be used to the determine specificity of fluoro-jade. Indeed, these studies demonstrated that fluoro-jade consistently reproduced insult specific staining patterns of neuronal degeneration that were identical to H&E and de Olmos’ cupric staining patterns after the same neurotoxic insults. These results suggest that fluoro-jade is a reliable marker of neurodegeneration.[1]

Larry Schmued suggests that a basic "death molecule" is expressed by damaged cells and that the highly anionic and acidic fluoro-jade may be specific for this target.[1] Further supporting the validity of fluoro-jade stain and this hypothesis is the work of Auer et al.,[4] who demonstrated that another anionic dye, fuchsine acid, could successfully bind to damaged neurons after a hyperglycemic insult presumably by the same electrostatic mechanism as fluoro-jade. These neurons were characterized by cell death morphology including condensed chromatin, a disrupted plasma membrane, and a disrupted nuclear membrane.

Although fluoro-jade and de Olmos’ silver stain have the same pattern of staining in models of neurotoxicity, there are inherent differences between the two methodologies that may have physiological implications. For example, a time course analysis of neuronal degeneration between the two techniques shows that silver stain is evident earlier after a neurotoxic insult which may suggest that fluoro-jade is specific for a later, more committed stage of the degenerative process.[5]

Applications

Traumatic brain injury [6] [7]

Spinal cord injury [8]

Alzheimer's disease [9]

Aging [10]

Stroke [11] [12]

Epilepsy [5]

Alcoholism [13]

Drug abuse [14]

Other

Fluoro-jade may also be useful for other applications other than labeling degeneration neurons of the brain. Several reports have demonstrated that fluorojade is also useful in detecting glia, specifically reactive astroglia [15] and microglia .[16] Thus fluorojade may be used to assess glial responses associated with neurotoxicity. Additionally, other studies demonstrate that fluoro-jade can also label neurons outside the CNS such as neurons of the dorsal root ganglia.[17]

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Schmued LC, Albertson C, Slikker Jr. W (1997). "Fluoro-Jade: a novel fluorochrome for the sensitive and reliable histochemical localization of neuronal degeneration". Brain Res. 751 (1): 37–46. doi:10.1016/S0006-8993(96)01387-X. PMID 9098566. 
  2. Schmued LC, Hopkins KJ (August 2000). "Fluoro-Jade B: a high affinity fluorescent marker for the localization of neuronal degeneration". Brain Res. 874 (2): 123–30. doi:10.1016/S0006-8993(00)02513-0. PMID 10960596. 
  3. 3.0 3.1 3.2 Schmued LC, Stowers CC, Scallet AC, Xu L (February 2005). "Fluoro-Jade C results in ultra high resolution and contrast labeling of degenerating neurons". Brain Res. 1035 (1): 24–31. doi:10.1016/j.brainres.2004.11.054. PMID 15713273. 
  4. Auer R. N., Kalimo H., Olsson Y. and Siesjo¨ B. K. (1985). "The temporal evolution of hypoglycemic brain damage. I. Light- and electron-microscopic findings in the rat cerebral cortex.". Acta neuropath., Berl. 67 (1-2): 13–24. PMID 4024866. 
  5. 5.0 5.1 Poirier JL, Capek R, De Koninck Y (2000). "Differential progression of Dark Neuron and Fluoro-Jade labelling in the rat hippocampus following pilocarpine-induced status epilepticus". Neuroscience 97 (1): 59–68. doi:10.1016/S0306-4522(00)00026-9. PMID 10771339. 
  6. Anderson, K.J., Miller, K.M., Fugaccia, I., Scheff, S.W. (2005). "Regional distribution of Fluoro-Jade B staining in the hippocampus following traumatic brain injury". Experimental Neurology 193 (1): 125–130. doi:10.1016/j.expneurol.2004.11.025. PMID 15817271. 
  7. Hellmich, H.L., Capra, B., Eidson, K., Garcia, J., Kennedy, D., Uchida, T., Parsley, M., Cowar, J., DeWitt, D.S., Prough, D.S. (2005). "Dose-dependent neuronal injury after traumatic brain injury". Brain Res 1044 (2): 144–154. doi:10.1016/j.brainres.2005.02.054. PMID 15885213. 
  8. Anderson, K.J., Fugaccia, I., Scheff, S.W. (2003). "Fluoro-Jade B stains quiescent and reactive astrocytes in the rodent spinal cord". J of Neurotrauma 20 (11): 1223–1231. doi:10.1089/089771503770802899. PMID 14651809. 
  9. Damjanac, M., Rioux Bilan, A., Barrier, L., Pontcharraud, R., Anne, C., Hugon, J., Page, G. (2007). "Fluoro-Jade B staining as useful tool to identify activated microglia and astrocytes in a mouse transgenic model of Alzheimer's Disease". Brain Research 1128 (1): 40–49. doi:10.1016/j.brainres.2006.05.050. PMID 17125750. 
  10. Colombo, J. A., Puissant, V.I. (2002). "Fluoro Jade Stains Early and Reactive Astroglia in the Primate Cerebral Cortex". J of Histochem & cytochem 50 (8): 1135–1137. 
  11. Duckworth, E.A.M., Butler, T., Collier, L., Collier, S., Pennypacker, K. R. (2006). "NF-kappaB protects neurons from ischemia injury after middle cerebral artery occlusion in mice". Brain Research 1088 (1): 167–175. doi:10.1016/j.brainres.2006.02.103. PMID 16630592. 
  12. Duckworth, E.A.M., Bulter, T.L., De Mesquita, D., Collier, S.N., Collier, L., Pennypacker, K. R. (2005). "Temporary focal ischemia in the mouse: Technical aspects and patterns of Fluoro-Jade evident neurodegeneration". Brain Res 1042 (1): 29–36. doi:10.1016/j.brainres.2005.02.021. PMID 15823250. 
  13. Obernier,J.A., Bouldin, J.A., Crews, F.T. (2002). "Binge ethanol exposure in adult rats causes necrotic cell death". Alcohol Clin Exp Res 26 (4): 547–557. doi:10.1111/j.1530-0277.2002.tb02573.x. PMID 11981132. 
  14. Eisch, A.J., Schmued, L.C., Marshall, J.F. (1998). "Characterizing cortical neuron injury with fluoro-jade labeling after a neurotoxic regimen of methamphetamine". Synapse 30 (3): 329–333. doi:10.1002/(SICI)1098-2396(199811)30:3<329::AID-SYN10>3.0.CO;2-V. PMID 9776136. 
  15. Anderson, K.J., Isabella, F., Scheff, S.W. (2003). "Fluoro-jade stains quiescent and reactive astrocytes in the rodent spinal cord". Neurotrauma, J. 20 (11): 1223–1231. doi:10.1089/089771503770802899. PMID 14651809. 
  16. Damjanac, M., Rioux Bilan, A., Barrier, L., Pontcharraud, R., Anne, C., Hugon, J., Page, G. (2007). "Fluro-jade B staining as useful tool to identify activated microglia and astrocytes in a mouse transgenic model of Alzheimer's disease". Brain research 1128 (1): 40–49. doi:10.1016/j.brainres.2006.05.050. PMID 17125750. 
  17. Hornfelt, M., Edstrom, A., Ekstrom, P.A.R. (1999). "Upregulation of cytosolic phospholipase A2 correlates with apoptosis in mouse superior cervical and dorsal root ganglia neurons". Neuroscience Letters 265 (2): 87–90. doi:10.1016/S0304-3940(99)00046-4. PMID 10327175.