Quantification and localization of kainic acid-induced neurotoxicity employing a new biomarker of cell death: cleaved microtubule-associated protein-tau (C-tau).
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.
Zemlan
F P
FP
Department of Psychiatry, College of Medicine, 231 Sabin Avenue, University of Cincinnati, Cincinnati, OH 45267, USA. frank.zemlan@uc.edu
Mulchahey
J J
JJ
Gudelsky
G A
GA
D000818:Animals; D015415:Biomarkers / Q000032:analysis; D001921:Brain / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D001923:Brain Chemistry; D016923:Cell Death / Q000187:drug effects*; D002555:Cerebrospinal Fluid / Q000378:metabolism; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D018690:Excitatory Amino Acid Agonists / Q000633:toxicity*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D007608:Kainic Acid / Q000633:toxicity*; D008297:Male; D008868:Microtubule Proteins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D020890:Neuregulin-1 / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D020258:Neurotoxicity Syndromes / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016622:Silver Staining; D013345:Subarachnoid Hemorrhage / Q000134:cerebrospinal fluid; D013997:Time Factors; D016875:tau Proteins / Q000737:chemistry / Q000378:metabolism*
D015415:Biomarkers; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D008868:Microtubule Proteins; D008869:Microtubule-Associated Proteins; D020890:Neuregulin-1; D016875:tau Proteins; D016291:Dizocilpine Maleate; D007608:Kainic Acid