[Frontiers in Bioscience S4, 1547-1555, June 1, 2012]

Unaffected motor endplate occupancy in eye muscles of ALS G93A mouse model

Anton E. Tjust1,3, Thomas Brannstrom2, Fatima Pedrosa Domellof1,3

1Department of Integrative Medical Biology, Section for Anatomy, Umea University, SE-901 87 Umea, Sweden, 2Department of Medical Biosciences, Section for Pathology, Umea University, SE-901 85 Umea, Sweden, 3Department of Clinical Sciences, Ophthalmology Umea University, SE-901 87 Umea, Sweden


1. Abstract
2. Introduction
3. Materials and methods
3.1. Specimens
3.2. Immunohistochemistry
3.3. Analysis
3.4. Statistical Analysis
4. Results
5. Discussion
6. Acknowledgements
7. References


Amyotrophic lateral sclerosis (ALS) is a progressive, lethal neurodegenerative disorder characterised by selective loss of motor neurons with accompanying muscle paralysis and respiratory failure. Despite progressive paralysis in trunk and extremity muscles, disturbed eye motility is not a hallmark of ALS. Extraocular muscles (EOMs) of terminal ALS patients show far less morphological signs of disease than their limb muscles. One of the earliest signs of the disease in the transgenic G93A SOD1 mouse model of ALS is loss of motor neuron contact at the neuromuscular junctions (NMJ) in limb muscles. We used immunohistochemistry to identify NMJs and evaluate innervation in EOMs and limb muscles of G93A mice. In G93A limb muscles, loss of axonal contact was seen in 6-82 % of the NMJs. On the contrary, the degree of endplate occupancy in the EOMs did not differ between transgenic mice and wild-type controls. We propose that EOM-specific properties make these muscles more resistant to the underlying pathophysiological process of ALS and that the EOMs are a useful model to advance our understanding of ALS.