Lithium prevents excitotoxic cell death of motoneurons in organotypic slice cultures of spinal cord.
Several studies have reported the neuroprotective effects of lithium (Li) suggesting its potential in the treatment of neurological disorders, among of them amyotrophic lateral sclerosis (ALS). Although the cause of motoneuron (MN) death in ALS remains unknown, there is evidence that glutamate-mediated excitotoxicity plays an important role. In the present study we used an organotypic culture system of chick embryo spinal cord to explore the presumptive neuroprotective effects of Li against kainate-induced excitotoxic MN death. We found that chronic treatment with Li prevented excitotoxic MN loss in a dose dependent manner and that this effect was mediated by the inhibition of glycogen synthase kinase-3beta (GSK-3beta) signaling pathway. This neuroprotective effect of Li was potentiated by a combined treatment with riluzole. Nevertheless, MNs rescued by Li displayed structural changes including accumulation of neurofilaments, disruption of the rough endoplasmic reticulum and free ribosome loss, and accumulation of large dense core vesicles and autophagic vacuoles. Accompanying these changes there was an increase in immunostaining for (a) phosphorylated neurofilaments, (b) calcitonin gene-related peptide (CGRP) and (c) the autophagic marker LC3. Chronic Li treatment also resulted in a reduction in the excitotoxin-induced rise in intracellular Ca(2+) in MNs. In contrast to the neuroprotection against excitotoxicity, Li was not able to prevent normal programmed (apoptotic) MN death in the chick embryo when chronically administered in ovo. In conclusion, these results show that although Li is able to prevent excitotoxic MN death by targeting GSK-3beta, this neuroprotective effect is associated with conspicuous cytopathological changes.
Calderó
J
J
Unitat de Neurobiologia Cel.lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), C. Montserrat Roig 2, Catalonia, Spain. jordi.caldero@mex.udl.cat
Brunet
N
N
Tarabal
O
O
Piedrafita
L
L
Hereu
M
M
Ayala
V
V
Esquerda
J E
JE
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002642:Chick Embryo; D004305:Dose-Response Relationship, Drug; D004359:Drug Therapy, Combination; D018690:Excitatory Amino Acid Agonists / Q000633:toxicity; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D066298:In Vitro Techniques; D007608:Kainic Acid / Q000633:toxicity; D008094:Lithium / Q000008:administration & dosage / Q000494:pharmacology*; D009046:Motor Neurons / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D018696:Neuroprotective Agents / Q000008:administration & dosage / Q000494:pharmacology*; D019782:Riluzole / Q000008:administration & dosage / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D013116:Spinal Cord / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure
D018690:Excitatory Amino Acid Agonists; D018696:Neuroprotective Agents; D019782:Riluzole; D008094:Lithium; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3; D007608:Kainic Acid; D002118:Calcium