A systematic study of brainstem motor nuclei in a mouse model of ALS, the effects of lithium
Introduction
Amyotrophic lateral sclerosis (ALS) is a progressive, devastating neurodegenerative disease that affects primarily motor neurons (MN) of the spinal cord, brainstem and motor cortex (Wijesekera and Leigh, 2009, Cleveland and Rothstein, 2001). The clinical symptoms include weakness, muscle atrophy and fasciculations, death occurs in 3–5 years from diagnosis (Rowland and Shneider, 2001).
When the motor nuclei of the brainstem are involved at the onset of disease (roughly, 25% of cases), the clinical outcome is the most severe leading to death in less than 1 year from diagnosis (Kühnlein et al., 2008). In fact, the involvement of the brainstem leads to dysarthria, dysphagia and impairment of swallowing and breathing all due to a damage of hypoglossal, trigeminal and ambiguus nuclei. Also the facial nucleus is affected and contributes to these symptoms (Kusaka et al., 1988, Hartmann et al., 1989). In contrast, oculomotor nuclei are relatively spared (Gizzi et al., 1992, Okamoto et al., 1993).
Based on the knowledge of inherited ALS in humans, a variety of mouse strains have been generated. Among these, the most studied is the G93A mouse, where a point mutation in the human gene coding the enzyme superoxide dismutase type-1 (SOD1) leads to a 93 glycine/alanine substitution. These mice develop a rapidly progressive MN disease, which leads to hindlimb paralysis and death (Gurney et al., 1994, Ripps et al., 1995, Gurney, 1997). This phenotype recapitulates several clinical and histopathological features of both familial and sporadic forms of the human disease (Gurney et al., 1994, Gurney, 1997, Newbery and Abbott, 2001). Although lumbar spinal cord is the site of onset and it is mostly affected, MN degeneration also occurs at higher levels of the cord and brainstem. It is surprising that, despite brainstem degeneration was described in this mouse model, and the brainstem involvement leads to the worst prognosis of ALS in humans, only a few studies investigated the brainstem motor nuclei in the G93A mouse.
Therefore, we decided to analyze the entire population of somatic brainstem motor nuclei of the G93A mouse also including the parasympathetic nucleus dorsalis of the vagus.
Within these nuclei, we counted the degeneration occurring at the end of the natural course of the disease, and we evaluated the effects of lithium. In fact, recent reports (Shin et al., 2007, Fornai et al., 2008a, Fornai et al., 2008b, Feng et al., 2008, Pasquali et al., 2009) indicate that chronic lithium administration protects G93A mice from MN degeneration (Shin et al., 2007; for a review, see Pasquali et al., 2009 ; Young, 2009) and rescues the behavioural and pathological deficit occurring following a spinal cord transection (Dill et al., 2008). These effects are concomitant with lithium-induced increased neuron number and decreased gliosis as shown both in degenerating (Fornai et al., 2008a, Fornai et al., 2008b) and lesioned (Su et al., 2007, Su et al., 2009) spinal cords as well as lithium-induced sprouting of corticospinal (Dill et al., 2008) and rubrospinal (Yick et al., 2004) tracts.
Section snippets
Animals
We used male mice from our own colony originated from the G93A mouse strain originally obtained from the Jackson laboratories (Bar Harbor, ME, USA). Selective breeding maintained the transgene in the hemizygous state in an F1 hybrid C57BL6xSJL genetic background. Colony maintenance and screening for the presence of the human transgene were performed as described (Spalloni et al., 2006). In addition, we replicated the experiments in G93A mice directly purchased from Jackson laboratories (Bar
Results
Chronic lithium administration extended the survival time and significantly improved the motor function of the G93A mouse used in this study, confirming our previous publication (Fornai et al., 2008a, Fornai et al., 2008b). In Supplementary Fig. 1, presented are the results of the motor function tests (Rotarod, PaGe and stride length) and the survival time. In this experimental context, the increased neuron number and the decreased vacuolization in the spinal cord were confirmed here as shown
Discussion
In the present paper, we analyzed all brainstem motor nuclei in the G93A mouse showing the reliability of this experimental model to reproduce the bulbar involvement of ALS. Moreover, by profiting of this experimental setting, we characterized the effects of lithium in counteracting the loss of brainstem motor neurons thus extending previous findings obtained in the spinal cord.
In fact, ALS is characterized by the degeneration of motor neurons in the spinal cord, brainstem, and motor cortex (
References (69)
- et al.
Axotomy along with hypoxia enhances the neuronal NADPH-d/NOS expression in lower brain stem motor neurons of adult rats
Exp. Neurol.
(2001) Amyotrophic lateral sclerosis: a 40-year personal perspective
J. Clin. Neurosci.
(2009)- et al.
Combined lithium and valproate treatment delays disease onset, reduces neurological deficits and prolongs survival in an amyotrophic lateral sclerosis mouse model
Neuroscience
(2008) - et al.
A simple method to measure stride length as an index of nigrostriatal dysfunction in mice
J. Neurosci. Methods
(2002) - et al.
Ultrastructure of blood–brain barrier and blood–spinal cord barrier in SOD1 mice modeling ALS
Brain Res.
(2007) - et al.
Differential vulnerability of cranial motoneurons in mouse models with motor neuron degeneration
Neurosci. Lett.
(2002) - et al.
Human Cu/Zn superoxide dismutase (SOD1) overexpression in mice causes mitochondrial vacuolization, axonal degeneration, and premature motoneuron death and accelerates motoneuron disease in mice expressing a familial amyotrophic lateral sclerosis mutant SOD1
Neurobiol. Dis.
(2000) - et al.
Different astroglial reaction between the vagal dorsal motor nucleus and nucleus ambiguus following vagal-hypoglossal nerve anastomosis in cats
Brain Res.
(2000) - et al.
Synaptic remodeling in the nucleus ambiguus following vagal-hypoglossal nerve anastomosis in the cat
Brain Res.
(2004) - et al.
Degeneration of respiratory motor neurons in the SOD1 G93A transgenic rat model of ALS
Neurobiol. Dis.
(2006)
Pharmacological inhibitors of glycogen synthase kinase 3
Trends Pharmacol. Sci.
Autophagy and the ubiquitin-proteasome system: collaborators in neuroprotection
Biochim. Biophys. Acta
Of mice, men and motor neurons
Trends Genet.
In vivo quantification of spinal and bulbar motor neuron degeneration in the G93A-SOD1 transgenic mouse model of ALS by T2 relaxation time and apparent diffusion coefficient
Exp. Neurol.
Experimental regimen targeting the ependyma slows disease progression in four patients with amyotrophic lateral sclerosis
Med. Hypotheses
Lithium prevents stress-induced reduction of vascular endothelium growth factor levels
Neurosci. Lett.
Molecular and synaptic changes in the hippocampus underlying superior spatial abilities in pre-symptomatic G93A+/+ mice overexpressing the human Cu/Zn superoxide dismutase (Gly93→ALA) mutation
Exp. Neurol.
Lithium enhances proliferation and neuronal differentiation of neural progenitor cells in vitro and after transplantation into the adult rat spinal cord
Exp. Neurol.
Mild hypoxic preconditioning attenuates injury-induced NADPH-d/nNOS expression in brainstem motor neurons of adult rats
J. Chem. Neuroanat.
Autophagy in neurodegeneration and development
Biochim. Biophys. Acta
Glycogen synthase kinase-3 in neurodegeneration and neuroprotection: lessons from lithium
Curr. Alzheimer Res.
Axon reaction in dorsal motor vagal and hypoglossal neurons of the adult rat. Light microscopy and RNA-cytochemistry
J. Comp. Neurol.
Age-dependent changes in MRI of motor brain stem nuclei in a mouse model of ALS
Neuroreport
VEGF delivery with retrogradely transported lentivector prolongs survival in a mouse ALS model
Nature
Validation of quality of life instruments in ALS
Amyotroph. Lateral. Scler. Other Mot. Neuron Disord.
Vacuolization correlates with spin-spin relaxation time in motor brainstem nuclei and behavioural tests in the transgenic G93A-SOD1 mouse model of ALS
Eur. J. Neurosci.
From Charcot to Lou Gehrig: deciphering selective motor neuron death in ALS
Nat. Rev. Neurosci.
Inactivation of glycogen synthase kinase 3 promotes axonal growth and recovery in the CNS
J. Neurosci.
Lithium, a potential protective drug in Alzheimer's disease
Neurodegener. Dis.
Lithium delays progression of amyotrophic lateral sclerosis
Proc. Natl. Acad. Sci. U. S .A.
Autophagy and amyotrophic lateral sclerosis: the multiple roles of lithium
Autophagy
Ocular motor function in motor neuron disease
Neurology
Lithium upregulates vascular endothelial growth factor in brain endothelial cells and astrocytes
Stroke
Motor neuron degeneration in mice that express a human Cu,Zn superoxide dismutase mutation
Science
Cited by (75)
Lithium engages autophagy for neuroprotection and neuroplasticity: Translational evidence for therapy
2023, Neuroscience and Biobehavioral ReviewsRespiratory pathology in the Optn<sup>-/-</sup> mouse model of Amyotrophic Lateral Sclerosis
2020, Respiratory Physiology and NeurobiologyIntralingual and Intrapleural AAV Gene Therapy Prolongs Survival in a SOD1 ALS Mouse Model
2020, Molecular Therapy Methods and Clinical DevelopmentNeuroprotective effects of lithium in neuropsychiatric disorders
2020, Neuroprotection in Autism, Schizophrenia and Alzheimer's Disease
- 1
Equally contributed to the present work.