Ciliary neurotrophic factor is a regulator of muscular strength in aging

Ciliary neurotrophic factor (CNTF) participates in the survival of motor ne urons and reduces the denervation-induced atrophy of skeletal muscles. Expe riments performed in rats show a decrease in peripheral CNTF synthesis duri ng aging, associated with an overexpression of its alpha-binding receptor c omponent by skeletal muscles. Measurement of sciatic nerve CNTF production and of the muscular performance developed by the animals revealed a strong correlation between the two studied parameters (r = 0.8; p < 0.0003). Furth ermore, the twitch and tetanic tensions measured in the isolated soleus ske letal muscle in 24-month-old animals increased 2.5-fold by continuous in vi vo administration of CNTF. Analyses of the activation level of leukemia inh ibitory factor receptor beta- and signal transducer and activator of transc ription 3-signaling molecules in response to exogenous CNTF revealed an inc reased tyrosine phosphorylation positively correlated with the twitch tensi on developed by the soleus muscle of the animals.