Motor Dysfunction and Lifespan Analysis
Objective: Measurement of onset of motor dysfunction and lifespan extension in Bax-deficient SOD1 mutant mice to determine whether motor neuron death is essential for ALS pathogenesis
Protocol Steps
Animal Breeding and Genetic Crossing
Bax-deficient mice were crossed with mice expressing mutant superoxide dismutase 1 (SOD1) to generate experimental animals for the study
Note: This created a transgenic model combining Bax deletion with SOD1 G93A mutation
View evidence from paper
“crossing Bax-deficient mice with mice expressing mutant superoxide dismutase 1 (SOD1), a transgenic model of familial ALS”
Motor Dysfunction Onset Assessment
Onset of motor dysfunction was monitored and recorded in both SOD1 mutant and Bax-deficient SOD1 mutant mice
Note: Bax deficiency delayed the onset of motor dysfunction in SOD1 mutants
View evidence from paper
“Bax deficiency extended lifespan and delayed the onset of motor dysfunction of SOD1 mutants”
Lifespan Measurement
Lifespan was measured and compared between SOD1 mutant mice and Bax-deficient SOD1 mutant mice
Note: Bax deletion extended lifespan in SOD1 mutants
View evidence from paper
“Bax deficiency extended lifespan and delayed the onset of motor dysfunction of SOD1 mutants”
Neuromuscular Denervation Analysis
Onset and progression of neuromuscular denervation was assessed in both experimental groups
Note: Bax elimination delayed the onset of neuromuscular denervation; denervation began long before activation of cell death proteins
View evidence from paper
“Bax elimination delayed the onset of neuromuscular denervation, which began long before the activation of cell death proteins in SOD1 mutants”
Mitochondrial Vacuolization Assessment
Mitochondrial vacuolization was examined in motor neurons
Note: Bax deletion failed to prevent mitochondrial vacuolization despite preventing motor neuron death
View evidence from paper
“Although Bax deletion failed to prevent neuromuscular denervation and mitochondrial vacuolization, MNs were completely rescued from mutant SOD1-mediated death”
Motor Neuron Death Assessment
Motor neuron survival was evaluated in both SOD1 mutant and Bax-deficient SOD1 mutant mice
Note: Motor neurons were completely rescued from mutant SOD1-mediated death in Bax-deficient mice
View evidence from paper
“MNs were completely rescued from mutant SOD1-mediated death”
Mutant SOD1 Accumulation Analysis
Accumulation of mutant SOD1 within motor neurons was assessed and compared between groups
Note: Denervation preceded accumulation of mutant SOD1 within motor neurons; accumulation was delayed in Bax-deficient SOD1 mutants
View evidence from paper
“denervation preceded accumulation of mutant SOD1 within MNs and astrogliosis in the spinal cord, which are also both delayed in Bax-deficient SOD1 mutants”
Astrogliosis Assessment
Astrogliosis in the spinal cord was evaluated in both experimental groups
Note: Astrogliosis was delayed in Bax-deficient SOD1 mutants compared to SOD1 mutants alone
View evidence from paper
“astrogliosis in the spinal cord, which are also both delayed in Bax-deficient SOD1 mutants”
Mitochondrial Abnormalities at Neuromuscular Junction
Mitochondrial abnormalities were examined at the innervated neuromuscular junction
Note: Motor neurons exhibited mitochondrial abnormalities at the neuromuscular junction at the onset of denervation
View evidence from paper
“MNs exhibited mitochondrial abnormalities at the innervated neuromuscular junction at the onset of neuromuscular denervation”
Presynaptic Terminal and Schwann Cell SOD1 Expression Analysis
Expression levels of mutant SOD1 in motor neuron presynaptic terminals and terminal Schwann cells were assessed
Note: Both motor neuron presynaptic terminals and terminal Schwann cells expressed high levels of mutant SOD1 before motor neurons withdrew their axons
View evidence from paper
“both MN presynaptic terminals and terminal Schwann cells expressed high levels of mutant SOD1 before MNs withdrew their axons”
Cell Death Protein Activation Assessment
Activation of cell death proteins was monitored in motor neurons
Note: Neuromuscular denervation began long before activation of cell death proteins in SOD1 mutants
View evidence from paper
“denervation began long before the activation of cell death proteins in SOD1 mutants”