Effects of cardiotrophin-1 (CT-1) in a mouse motor neuron disease

Cardiotrophin-1 (CT-1) has potent survival-promoting effects on motor neurons in vitro and in vivo and may be effective in treating motor neuron diseases (MND). We investigated the effects of CT-1 treatment in wobbler mouse MND. Wobbler mice were randomly assigned to receive subcutaneously injected CT-1 (1 mg/kg, n = 18, in two experiments) or vehicle (n = 18, in two experiments) daily, 6 times/week for 4 weeks after clinical diagnosis at age 3 to 4 weeks. Cardiotrophin-1 treatment prevented deterioration in paw position and walking pattern abnormalities. Grip strength declined steadily in the vehicle group, whereas in the CT-1 group it declined at week 1 but increased thereafter to exceed baseline strength by 5% (P = 0.0002) at week 4. Running speed was faster with CT-1 (P = 0.007). Biceps muscle twitch tension, muscle weight, mean muscle fiber diameter, and intramuscular axonal sprouting were significantly greater with CT-1 treatment than with vehicle treatment. Histometry revealed a trend that indicated CT-1 modestly increased the number of immunoreactive motor neurons, as determined by both choline acetyltransferase and c-Ret antibodies, and reduced the number of phosphorylated neurofilament immunoreactive perikarya (P = 0.05). The number of large myelinated motor axons significantly increased with treatment (206 versus 113, P = 0.01). We conclude that CT-1 exerts myotrophic effects as well as neurotrophic effects in a mouse model of spontaneous MND, a finding that has potential therapeutic implications for human MND.