[Interpretation of dark neurons in experimental model of ischemia, neurointoxication and brain infection].

INTRODUCTION: Findings of dark neurons is still a big controversy. Do they represent a simple artifact or neuropatological findings? The aim is to explain the appearance of "dark" neurons in different experimental animal models.

MATERIAL AND METHODS: The experiments included three experimental models. Neuroischemia: where in postmortal fixed rat brain after 10', 30', 45', 1.5h, 3h, 6h, 12h, 24h histologically was examined the appearance of dark neurons; intoxication: after 28 days of oral administratio AlCl3 in rats analyse changes in the brain; neuroinfection: where hamsters perorally given culture larvae T. canis and after 5 weeks analyse neuropatological findings in the brain. All brains were processed by standard histological techniques and stained with H&E, Walton and Cresil violet methods.

RESULTS: Neuroishemia--in the group fixed brain specimens after 10 and 30' found only insignificant number of dark neurons increases until the time of fixation, their number was increasing, and after 12 and 24 hours dark shape assumed virtually all neurons. Neuroinfection: laminar flow is characterized by deterioration of nerve cells and the concentration of dark neurons in V lamina of cerebral cortex. Neuroinfection--in the area granulomatous pathohistological lesions and other changes observed increased concentration of irreversible stages of dark neurons.

DISCUSSION AND CONCLUSION: The same histopathology characteristics of dark neurons in all experimental models can be attributed to postmortem artificial ischemia, to which to every tissue is exposed during histological processing. The abundance of appearance of dark neurons depend on the length of exposure to ischemia and the previous patophysiological state of tissue especially if the pretreatment included a harmful substances. Any harmful substances leading to pathophysiological changes in vivo cause increased sensitivity of cells to arteficial ischemia and the development of dark neurons.