Coordination of Locomotor Activity in Transgenic C57Bl/6 Mice with Hereditary Neuropathy

Locomotor activity of C57Bl/6 mice with hereditary motor and sensory neuropathy (HMSN; an animal model of Charcot-Marie-Tooth, CMT, disease) was investigated in males and females of two ages (15 and 20 weeks) using the balance beam test (inclined beam); such indices as time of traveling via the beam to the shelter and number of slippings of the hindlimbs from the beam were recorded. It was found that C57Bl/6 mice spent dramatically more time for traveling than control C57Bl mice with no neuropathy, and the number of erroneous movements (slippings of the hindlimbs) during traveling in mice with HMSN was many times greater than that in the controls. The deficiency of control of locomotion in C57Bl/6 animals was found to be sex- and age-dependent. Females of this strain moved significantly slower than males of the same age categories; both 20-week-old males and females with HMSN spent significantly more time for traveling the test distance than 15-week-old animals and demonstrated more motor failures. Thus, symptoms of HMSN are more pronounced in females (probably due to the specificity of the hormonal background in the latter), and the severity of pathology increases with age. The balance beam test appears acceptable for obtaining easily interpretable quantitative characteristics of the quality of locomotion control in experimental animal models of neuropathies.