Summary
The agent responsible for inducing neuritic (senile) plaque formation in senile dementia of the Alzheimer's type and in the ageing non-demented brain is unknown. Other workers have detected a high concentration of silicon in the rims and cores of senile neuritic plaques. We have therefore looked at whether the reaction of brain tissue to silica particles resembles a neuritic plaque. In this study both fine (10 nm) and coarse (<5 μm) particles of silica have been introduced into the brains of rats and mice using a wide range of doses and several methods of administration. The reaction of the brain to the presence of the silica was examined by light and electronmicroscopy up to one year after the injection.
The presence of silica particles in the brain resulted in the proliferation of fibrous astrocytes and macrophages and strongly stimulated the production of collagen fibres. Degeneration of some adjacent axons and axon terminals occurred, but there was no detectable deposition of amyloid which is characteristic of senile plaques. Coarse particles of silica invariably produced a more intense reaction than fine particles. The reaction of the brain did not diminish with time within one year of injection.
The possible significance of the presence of silica in the plaque as a secondary phenomenon is discussed.
Similar content being viewed by others
References
Allison AC, Harrington JS, Birbeck M (1966) An examination of the cytotoxic effects of silica on macrophages. J Exp Med 124: 141–154
Austin JH (1978) Silicon levels in human tissues. In: Runnström-Reio V (Administrative ed) Biochemistry of silicon and related problems: Nobel Symposium, 40th, Lindingö, Sweden 1977. Plenum Press, New York London, pp 255–268
Austin JH, Rinehart R, Williamson T, Burcar P, Russ K, Nikaido T, LaFrance M (1973) Studies in ageing of the brain. III. Silicon levels in post mortem tissues and body fluids. In: Ford DH (ed) Progress in brain research, vol 40. Elsevier, Amsterdam, pp 485–495
Brightman MW, Hori M, Rapoport SI, Reese TS, Westergaard E (1973) Osmotic opening of tight junctions in cerebral endothelium. J Comp Neurol 152:317–326
Bruce ME, Fraser H (1975) Amyloid plaques in the brains of mice infected with scrapie: morphological variations and staining properties. Neuropathol Appl Neurobiol 1:189–202
Heppleston AG, Styles JA (1967) Activity of a macrophage factor in collagen formation by silica. Nature 214:521–522
Ishii T, Haga S (1976) Immuno-electron microscopic localisation of immunoglobulins in amyloid fibres of senile plaques. Acta Neuropathol (Berl) 36:243–249
King EJ, Belt TH (1940) The silica content of tissues with and without silicotic lesions. J Pathol 51:269–275
Nadler S, Goldfischer S (1970) The intracellular release of lysosomal contents in macrophages that have ingested silica. J Histochem Cytochem 18:368–371
Nagy Z, Pappius HM, Mathieson G, Huttner I (1979) Opening of tight junctions in cerebral endothelium. Part 1 (Effect of hyperosmolar mannitol infused through the internal carotid artery). J Comp Neurol 185:569–578
Nikaido T, Austin JH, Trueb L, Rinehart R (1972) Studies in ageing of the brain. II. Microchemical analyses of the nervous system in Alzheimer patients. Arch Neurol 27:549–554
Perl DP, Brody AR (1980) Alzheimer's disease: X-ray spectrometric evidence of aluminium accumulation in neurofibrillary tangle bearing neurones. Science 208:297–298
Puchtler H, Sweat F, Levine M (1961) On the binding of Congo red by amyloid. J Histochem Cytochem 10:355–364
Rapoport SI, Thompson HK (1973) Osmotic opening of the blood-brain barrier in the monkey without associated neurological deficits. Science 150:971
Rees S (1975) A quantitative electron microscopic study of atypical structures in normal human cerebral cortex. Anat Embryol (Berl) 148:303–331
Tomlinson BE (1974) Quantitative studies of some morphological changes in the brains of old people. Scand J Clin Lab Invest 34 [Suppl] 141:15–16
Trelstad RL (1971) Vacuoles in the embryonic chick corneal epithelium, an epithelium which produces collagen. J Cell Biol 48:689–694
Vaughan DW, Peters A (1981) The structure of neuritic plaques in the cerebral cortex of aged rats. J Neuropathol Exp Neurol 40:472–489
Vigliani EC, Pernis B (1958) Immunological factors in the pathogenesis of the hyaline tissue of silicosis. Br J Ind Med 15:8–14
Wiśniewski HM, Bruce ME, Fraser H (1975) Imectious etiology of neuritic (senile) plaques in mice. Science 190:1108–1110
Wiśniewski HM, Lossinsky AS, Moretz RC, Vorbrodt AW (1981) Neuritic plaque formation and blood-brain barrier (BBB) changes in scrapie. J Neuropathol Exp Neurol 40:342
Wiśniewski HM, Terry RD (1973) Morphology of the ageing brain, human and animal. In: Ford DH (ed) Progress in brain research, vol 40. Elsevier, Amsterdam, pp 167–186
Young MB (1977) H3T labelled blood cells in the central nervous response to axotomies at various times after isotope injection. J Neuropathol Exp Neurol 36:465–473
Author information
Authors and Affiliations
Additional information
Supported by a National Health and Medical Research Council Grant
Rights and permissions
About this article
Cite this article
Rees, S., Cragg, B. Is silica involved in neuritic (senile) plaque formation?. Acta Neuropathol 59, 31–40 (1983). https://doi.org/10.1007/BF00690314
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00690314