Primary neurologic screening and motor coordination of Dstdt-J mutant mice (dystonia musculorum) with spinocerebellar atrophy.

The autosomal recessive dystonia musculorum (Dst(dt-J)) mutation causes degenerative lesions of peripheral and central sensory pathways. A test battery of motor, sensory, postural, and autonomic functions was used to compare young control and homozygous Dst(dt-J) mice. The Dst(dt-J) mutants were severely impaired for muscle strength, limb coordination, and postural reflexes. As a result of a loss in motor control, the mutants were hypoactive in the open-field and fell quickly from the stationary beam. In sensory tests, the acoustic startle response was impaired, but not tactile reflexes and contact righting, attesting to preserved labyrinthine function and non-lemniscal pathways. Dst(dt-J) mutants were also distinguishable from controls on the basis of tremor, a paler skin, piloerection, and half-open eyes, as well as low body weight and fecal boli. Grooming episodes were less frequent in the mutants but without any reduction in grooming time. The neurologic screening battery delineated the functional integrity of some sensorimotor pathways in a spinocerebellar mutant whose severe phenotype prevents a more elaborate evaluation.