Autonomic impairment in a transgenic mouse model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by progressive loss of motor neurons, however it is increasingly recognized that nonmotor manifestations may occur, including autonomic nervous system dysfunction. To better understand the autonomic involvement in ALS we measured autonomic functions in transgenic (TG) mice carrying an SOD1 (G93A) mutation and wild-type (WT) control mice. TG mice had a higher heart rate at rest and following stress than WT mice at all ages except for the advanced stages of the disease (19-20. weeks of age). The mean pupil diameter at rest was similar in WT and TG mice; however, TG mice had decreased mydriasis following administration of morphine. The rectal temperature did not differ between TG and WT mice at rest, during exposure to cold stress and following administration of morphine (30. mg/kg) except for the advanced stages of the disease in which TG mice had significantly lower temperatures than WT mice during cold stress and following morphine administration. The results suggest autonomic nervous system impairment in this ALS model, consistent with clinical data in humans.