Quantification and localization of kainic acid-induced neurotoxicity employing a new biomarker of cell death: cleaved microtubule-associated protein-tau (c-tau)

• Published in: Neuroscience Vol. 121; no. 2; pp. 399 - 409
• Main Authors: Zemlan, F.P, Mulchahey, J.J, Gudelsky, G.A
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-01-2003; Elsevier
• Subjects: Animals; Biochemistry and metabolism; Biological and medical sciences; Biomarkers - analysis; Brain - cytology; Brain - drug effects; Brain - metabolism; Brain Chemistry; C-tau; Cell Death - drug effects; Central nervous system; Cerebrospinal Fluid - metabolism; Dizocilpine Maleate - pharmacology; ELISA; Enzyme-Linked Immunosorbent Assay; Excitatory Amino Acid Agonists - toxicity; Excitatory Amino Acid Antagonists - pharmacology; Fundamental and applied biological sciences. Psychology; Humans; Immunoblotting; Immunohistochemistry; kainic acid; Kainic Acid - toxicity; Male; Microtubule Proteins - metabolism; Microtubule-Associated Proteins - metabolism; Neuregulin-1 - metabolism; neurodegeneration; Neurons - cytology; Neurons - metabolism; neurotoxicity; Neurotoxicity Syndromes - metabolism; Rats; Rats, Sprague-Dawley; Silver Staining; Subarachnoid Hemorrhage - cerebrospinal fluid; tau Proteins - chemistry; tau Proteins - metabolism; Time Factors; Vertebrates: nervous system and sense organs; PBS; kainic acid; TBS; neurodegeneration; TBST; GFAP; Mab; CT; neurotoxicity; CSF; C-tau; immunohistochemistry; BME; SAH; ELISA; MAP-tau; Rat; Toxicity; Rodentia; Central nervous system; Biological marker; Encephalon; Vertebrata; Mammalia; Tau protein; Cell death; Excitotoxicity; Microtubule associated protein; Localization; Kainic acid
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/S0306-4522(03)00459-7

Previous studies of neuronal degeneration induced by the neurotoxin, kainic acid, employed silver stain techniques that are non-quantitative or ELISA measurement of the non-neuronal protein, glial fibrillary acidic protein. As previous studies employed biomarkers that were either non-quantitative or non-neuronal, the present study employed a new neuronally localized biomaker of neuronal damage, cleaved microtubule-associated protein (MAP)-tau (C-tau). The time course of kainate neurotoxicity was quantitatively determined in several brain regions in the present study employing a C-tau specific ELISA. Differences in ELISA determined regional brain levels of C-tau were compared with the density of somatodendritic C-tau labeling qualitatively determined in immunohistochemical anatomical mapping studies of kainic acid-treated animals.
Immunoblot studies revealed that the C-tau antibodies employed in the present study were highly specific for proteolytic cleaved C-tau. Immunolabeling of 45 kD–50 kD C-tau proteins was observed only in brain samples from kainic acid-treated but not vehicle-treated rats. Time course studies revealed that C-tau levels determined by ELISA were maximal 3 days after kainic acid with C-tau levels increasing 26-fold in hippocampus, 16-fold in cortex and four-fold in both striatum and hypothalamus. These statistical differences in maximal C-tau levels observed in the ELISA studies were similar to differences qualitatively observed in C-tau immunohistochemical studies. C-tau immunohistochemistry revealed extensive damage in hippocampal regions CA1 and 3, moderate damage in several cortical regions and mild damage in striatum and hypothalamus.
Similar cleavage of rat MAP-tau to C-tau has been reported after neuronal degeneration induced by neurotoxic doses of methamphetamine and neuronal degeneration resulting from bacterial meningitis. In humans, C-tau proteolysis has been demonstrated to be a reliable biomarker of neuronal damage in traumatic brain injury and stroke where cerebrospinal C-tau levels are correlated with patient clinical outcome. These data suggest that C-tau proteolysis may prove a reliable species independent biomarker of neuronal degeneration regardless of source of injury.