Differential cortico-motoneuron vulnerability after chronic mitochondrial inhibition in vitro and the role of glutamate receptors.
Chronic treatment of rat cortical slices with a relative low concentration of mitochondrial inhibitor malonate leads to cortical motoneuron (CMN) death. In the neurodegenerative disease amyotrophic lateral sclerosis (ALS) corticospinal neurons, CMNs projecting to the spinal cord, degenerate. In the present study we compared the effect of chronic mitochondrial inhibition on the survival of CMNs located in the dorsal cortical areas (including corticospinal neurons) with that on ventrally located CMNs (non-corticospinal neurons) in vitro. In the explant culture model used, the dorsally located CMNs were less vulnerable to a 2-week period of mitochondrial inhibition with malonate as compared to ventrally located CMNs. Treatment with 5 mM malonate resulted in 50% surviving CMNs in the dorsal part and only 16% in the ventral part. Neuroprotection of the CMNs could be achieved with co-administration of the non-NMDA antagonist CNQX, the NMDA antagonist MK-801, or the glutamate release inhibitor riluzole, suggesting that chronic energy shortage leads to excitotoxicity. In the dorsal cortical areas CNQX, MK-801, and riluzole had a neuroprotective effect on the CMNs, whereas in the ventral cortical areas only MK-801 was neuroprotective. The sensitivity to energy depletion and consequently excitotoxicity may be related to glutamate receptor density and subunit composition in various cortical areas, but also to the projection length and input of CMNs in vivo. The present investigation gives insight in mechanisms leading to excitotoxic cell death of CMNs and may therefore be important for the development of treatment strategies in protection and survival of cortical motoneurons in ALS.
Van Westerlaak
M G
MG
Department of Experimental Neurology, Room G02.320, RMI for Neurosciences, UMC Utrecht, P.O. Box 85500, 3508 GA, Utrecht, The Netherlands. m.g.h.vanwesterlaak@neuro.azu.nl
Joosten
E A
EA
Gribnau
A A
AA
Cools
A R
AR
Bär
P R
PR
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000690:Amyotrophic Lateral Sclerosis / Q000378:metabolism / Q000503:physiopathology; D000818:Animals; D000831:Animals, Newborn; D016923:Cell Death / Q000187:drug effects* / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions / Q000502:physiology; D004734:Energy Metabolism / Q000187:drug effects* / Q000502:physiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism; D007150:Immunohistochemistry; D008314:Malonates / Q000633:toxicity; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D009046:Motor Neurons / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D016900:Neurofilament Proteins / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology; D009924:Organ Culture Techniques; D011712:Pyramidal Tracts / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D017470:Receptors, Glutamate / Q000187:drug effects* / Q000378:metabolism
D018691:Excitatory Amino Acid Antagonists; D008314:Malonates; D016900:Neurofilament Proteins; D018696:Neuroprotective Agents; D017470:Receptors, Glutamate; D018698:Glutamic Acid; D016291:Dizocilpine Maleate; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione